This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. The scientists, Denghui Xu and Chihaya Adachi from the Center for Future Chemistry at Kyushu University in Fukuoka, Japan, have reported the liquid-OLED in a recent issue of Applied Physics Letters. As they explain, the novel design is based on a liquid-emitting layer, and could have advantages for flexible displays and other organic electronics applications.Usually, OLED displays use solid-state organic films that give off light when an electric current is applied. One significant benefit of OLED displays compared to traditional liquid crystal displays (LCDs) is that OLEDs do not require a backlight. For this reason, OLEDs can be made very thin and flexible, as well as use less power, enabling them to run longer on a single battery charge.The new liquid-OLED could achieve these same benefits, but by using a liquid organic semiconductor instead of the solid-state films. Other than a few previous studies that have investigated using polymer solutions as the semiconducting layer, this is the first time that researchers have attempted to fabricate a practical liquid semiconductor for OLEDs.As Xu and Adachi explain, their device uses ethylhexyl carbazole (EHCz) as the liquid semiconducting layer due to its high hole mobility, which is associated with good electrical conductivity. The scientists doped the EHCz with solid rubrene, which has a high photoluminescence efficiency. They then prepared a substrate with this liquid mixture placed in between an anode and cathode, which in turn were sandwiched by glass layers. When testing the device, the researchers observed electroluminescence from rubrene with the naked eye.“Since EHCz provides hole transport and rubrene does electron transport and emitting functions, the combination leads to electroluminescence,” Adachi told PhysOrg.com.The researchers hope that, by taking advantage of the new device’s unique liquid properties, they can make further improvements in OLED technology. For instance, liquid semiconductors could easily fill the space between two electrodes in curved structures without cracking or shortage problems. The researchers also suggest that the liquid semiconductors could be circulated or refilled into the active emitting layer. This constant, fresh supply of semiconductors could improve device reliability and reduce degradation.“This is quite a new concept, realizing truly flexible and degradation-free OLEDs,” Adachi said. “Although the electroluminescence efficiency is still low level, we can surely improve it by optimizing the device parameters and organic semiconductors.”More information: Denghui Xu and Chihaya Adachi. “Organic light-emitting diode with liquid emitting layer.” Applied Physics Letters 95, 053304 (2009).Copyright 2009 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. The new liquid-OLED has a liquid semiconducting layer made of EHCz doped with rubrene. Liquid-OLEDs could offer improved device reliability and greater flexibility. Credit: Xu and Adachi. Citation: Liquid-OLED Offers More Light-Emitting Possibilities (2009, August 14) retrieved 18 August 2019 from https://phys.org/news/2009-08-liquid-oled-light-emitting-possibilities.html Explore further Simple OLEDs ready for quick manufacturing (PhysOrg.com) — As organic light-emitting diodes (OLEDs) are poised to go mainstream in the near future, scientists continue to explore new twists on the technology. Recently, researchers have fabricated a “liquid-OLED” – an OLED that uses a liquid organic semiconducting layer to transport charge.
Explore further Citation: Physicists simulate sounds of the Higgs boson (w/ Video) (2010, June 23) retrieved 18 August 2019 from https://phys.org/news/2010-06-physicists-simulate-higgs-boson-video.html Michigan integral to world’s largest physics experiment You can listen to the sounds of different particles at www.LHCsound.com. One of several tracks available at the LHCsound website, the “Higgs Boson Simple” represents the sounds of an emerging and decaying Higgs boson. Credit: LHCsound. Although the project may give physicists a new tool to analyze their data, the main goal is to bring attention to the beauty in science, helping promote public awareness of science exploration. You can listen to sounds of the Higgs boson and other particles at the project’s website. The LHCsounds team, led by Asquith, is also working on developing cellphone ringtones and plans to host a public performance of the sounds performed by musicians from its scientific community. Musicians from around the world are also working with the sounds to incorporate them into compositions.”We can hear clear structures in the sound, almost as if they had been composed,” said Richard Dobson, a composer involved with the project. “They seem to tell a little story all to themselves. They’re so dynamic and shifting all the time, it does sound like a lot of the music that you hear in contemporary composition. You feel closer to the mystery of Nature which I think a lot of scientists do when they get deep into these matters.”To listen to more sounds of the LHC, visit www.lhcsound.com. “When you are hearing what the sonifications do you really are hearing the data,” said Archer Endrich, a composer and software engineer working on the project. “It’s true to the data, and it’s telling you something about the data that you couldn’t know in any other way.”Some of the data comes from Atlas, one of six detectors at the LHC. Atlas uses a calorimeter to measure the energy of the particles that collide inside of it. The calorimeter consists of seven concentric layers, each of which can be represented by a note. The note’s volume and pitch depend on the amount of energy deposited in that layer and its location in the layer, respectively. As physicist Lily Asquith explained, large amounts of energy make louder sounds than small amounts, while energy closer to an observer will have a higher pitch than energy located further away. (PhysOrg.com) — If particle physicists ever find the Higgs boson, they might be hearing its signature rather than – or in addition to – seeing it. The different sounds that particles make can give physicists another way to analyze their data, explains a team of physicists working on data sonification, which is the process of converting data into sounds. Partly for research and partly for public awareness, the scientists have simulated the sounds that the Higgs boson and other subatomic particles might make at the Large Hadron Collider (LHC). © 2010 PhysOrg.com More information: via: BBC News This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. read more
More information: Sound detection by the longfin squid (Loligo pealeii) studied with auditory evoked potentials: sensitivity to low-frequency particle motion and not pressure, by T. Aran Mooney et al., Journal of Experimental Biology 213, 3748-3759 (2010). doi:10.1242/jeb.048348 Citation: Squid shown to be able to hear (2011, February 8) retrieved 18 August 2019 from https://phys.org/news/2011-02-squid-shown.html Explore further Longfin inshore squid (Loligo pealeii). Image credit: NOAA. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Marine biologist T. Aran Mooney, a post-doctoral scholar at the Woods Hole Oceanographic Institution (WHOI) in Massachusetts measured the neural response to sounds in squid fitted with electrodes to detect nerve signals from the statocysts, two sac-like sensory organs near the base of the brain in squid.The longfin squid (Loligo pealeii) were in a tank and magnesium chloride was used to anesthetize them and keep them still, and underwater speakers (the kind used for synchronized swimmers) were used to play the sounds.The results of the research confirm that squid can hear low-frequency sounds between 30 and 500 Hz, but there was no response if the water temperature was less than 8°C. Dr Mooney said the squid would probably be able to hear waves, the sounds of reefs, and wind above, but would not be able to hear high-frequency sounds such as echo-location signals emitted by toothed whales and dolphins, which are the main predators of the squid. Unlike land animals, squid do not hear by detecting pressure changes produced by sound waves. Instead, they sense movements of the water that are produced by sound. Dr Mooney said the squid basically hears by detecting itself moving with the sound wave, and compared the process to a piece of fruit suspended in jelly. He said if you make the jelly wobble, the fruit moves as well as the jelly.The statocysts are fluid-filled sacs lined with hair cells that project into the sac. A tiny calcium carbonate grain called a statolith is also present inside each statocyst. In response to motions produced by sound the hair cells touch the statolith and generate signals that are sent to the brain. The hair cells in the squid statocysts are analogous to the hair cells in the cochlear in human ears, which convert vibrations in the air to signals that are then sent to the brain.The paper was published in The Journal of Experimental Biology. The researchers have now begun to investigate the squid’s relatively rudimentary sensory organ to see if it can shed light on the evolution of hearing in higher animals. Dr Mooney is also hoping to study the effect of “the burgeoning cacophony of human-generated sounds in the ocean” to see if it affects squid behavior or threatens their survival. Squid studies provide valuable insights into hearing mechanisms (PhysOrg.com) — Scientists in the US have solved the mystery about whether squid can hear and if so, how. © 2010 PhysOrg.com read more
Copyright 2011 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. “All of these 13 logic operations share the same initial state, that is, the molecule is always ‘reset’ to one and the same state by the use of green light, irrespective of which logic function is to be performed,” said Andréasson. “This is another unique feature of our molecule.”The researchers also demonstrated that the FG-DTE molecule can perform non-arithmetic functions. For example, as a digital multiplexer, the molecule can act as a mimic of a mechanical rotary switch to connect any one of several inputs to an output. As a demultiplexer, the molecule can separate two signals that have been multiplexed into one output.Further, the FG-DTE molecule can perform sequential logic functions, in which inputs must be applied in the correct order, such as for a keypad lock. The molecule can also operate as a transfer gate by transferring the state of an input to that of an output, which is useful for complicated computational operations. The researchers also demonstrated that the molecule can act as an encoder and decoder, by compressing digital information for transmission or storage, and then recovering the information in its original form.While each of these individual logic operations has previously been performed by molecular systems, the FG-DTE molecule is the first to unite them all in a single molecular platform. Transistors and other more traditional logic devices do not have the same functional flexibility, which the researchers attribute to the chromophores’ ability to respond differently to different wavelengths of light and to influence each other’s properties.As for applications, the researchers note that it’s unlikely that such molecular devices will soon replace electronic computers, but they could have applications in nanotechnology and biomedicine, such as for data storage, labeling and tracking micro-objects, and programmed drug release.“In the near term, molecular logic devices will complement, rather than compete with, electronic devices,” Gust said. “In principle, molecular computing could be implemented with extremely small switch sizes, since the operational units are molecules. Photonically operated molecular devices such as the one we describe can also be easily reconfigured to perform a variety of different logic functions, can operate at high speeds, and can be arrayed in three dimensions, rather than the planar arrangements usually found in electronics. “Molecular logic devices can be employed where electronic ones cannot,” he added. “For example, they can be used to label and track nanoparticles and nanoscale components of biological organisms. On the other hand, most photochromes currently are not sufficiently stable to stand up to the large number of cycles required for useful full-scale computing. In addition, complex computing will require convenient ways for nanoscale logic devices to communicate with one another.”“In addition, the application of molecular logic in biological systems, such as the human body, is still relatively unexplored, although molecular systems are better suited for this purpose compared to electronic devices,” said Andréasson.In the future, the researchers plan to address some of the biggest challenges facing molecular logic, such as the efficient wiring (concatenation) of logic switches.“One of the major challenges of molecular logic is concatenation of logic operations,” Gust said. “In electronics, this can be done simply by wiring the output of one element to the input of the next. We need to find ways of achieving similar results in molecules.” (PhysOrg.com) — While molecules have already been used to perform individual logic operations, scientists have now shown that a single molecule can perform 13 logic operations, some of them in parallel. The molecule, which consists of three chromophores, is operated by different wavelengths of light. The scientists predict that this system, with its unprecedented level of complexity, could serve as a building block of molecular computing, in which molecules rather than electrons are used for processing and manipulating information. Explore further Citation: Single molecule performs multiple logic operations simultaneously (2011, May 23) retrieved 18 August 2019 from https://phys.org/news/2011-05-molecule-multiple-logic-simultaneously.html (Left) The structure of the FG-DTE molecule, which is made of three photochromes that can switch between two different states when irradiated with light of different wavelengths. (Right) A checklist of some of the features of the all-photonic molecular logic device. Image credit: Joakim Andréasson, et al. ©2011 American Chemical Society. Read-write device offers new architecture for information processing More information: Joakim Andréasson, et al. “All-Photonic Multifunctional Molecular Logic Devices.” Journal of the American Chemical Society. DOI:10.1021/ja203456h The scientists and engineers, Joakim Andréasson from Chalmers University of Technology in Göteborg, Sweden; Uwe Pischel from the University of Huelva, Spain; and Stephen D. Straight, Thomas A. Moore, Ana L. Moore, and Devens Gust from Arizona State University, have published their study called “All-Photonic Multifunctional Molecular Logic Devices” in a recent issue of the Journal of the American Chemical Society.“While previous examples of molecular logic systems have been able to carry out one, or a few different logic operations, this molecule can be reconfigured to perform 13 simply by changing the input or output wavelengths,” Gust told PhysOrg.com. “In addition, it uses light for all inputs and outputs, which avoids some of the problems encountered when using chemicals as inputs.”In general, chromophores are the parts of a molecule that absorb light of specific wavelengths while transmitting other wavelengths, and are responsible for the molecule’s color. When chromophores can be switched between two different states by being irradiated with light of different wavelengths, they have the ability to perform binary logic operations and effectively serve as transistors. These photoswitchable, bistable chromophores are called photochromes.To thank our 25,000 fans in the Facebook community, this story was posted on the Physorg.com FB page a few hours before going live on the main siteHere, the researchers used three photochromes – one dithienylethene (DTE) and two fulgmides (FG) – to build a light-responsive molecule. Each of these photochromes can exist in either an open or closed isomeric form, and can be switched back and forth between forms with light pulses of different wavelengths. The two forms that each photochrome can take represent the two states that serve as the basis for performing binary logic operations. Various combinations of the three photochromes in different isomeric forms can be used to perform binary arithmetic, such as addition and subtraction. Although previous molecular-based systems have performed binary arithmetic, the FG-DTE molecule is the first that can perform these operations using only two inputs: light with wavelengths of 302 nm and 397 nm. Also, all three photochromes can be reset by green light irradiation (460-590 nm). These features allow the molecule to perform addition and subtraction in parallel, simply by having light convert the photochromes to different isomeric forms. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. read more
Citation: Bend-it e-books get real with EPD in factory mode (2012, March 30) retrieved 18 August 2019 from https://phys.org/news/2012-03-bend-it-e-books-real-epd-factory.html The company press release says the plastic EPD will be supplied to companies in China followed by completed products for release in Europe in early April. What’s more, some reports Thursday said the plastic displays were already being shipped to factories in China with target dates for completed products in April to debut in Europe. There was no word yet about any timetable being set for America. The report said it had begun producing six-inch e-ink panels on a plastic substrate for a Chinese-based ODM (original design manufacturer), for an end product with a release date of April, and that the end product would be in Europe.The company credits its production-ready success to a “manufacturing breakthrough” surmounting obstacles with temperatures over 350 degrees in LCD manufacturing. LG Display said its plastic EPD can maintain “strong durability” in high temperatures.The key talking point is “bendable.” The black and white electronic-ink product can bend at a range of 40 degrees from the center of the screen. This is an e-ink plastic screen that is 0.7mm thick, weighs 14g, and has slim protective film. The company’s comments regarding these details are that the product achieves “a super slim” thickness of 0.7mm which is one-third slimmer than existing glass EPD; and its weight of 14g is more than one-half lighter.The company maintains that this will help “greatly popularize” the e-book market,” in the words of Sang Duck Yeo, who heads operations for LG Display’s Mobile/OLED division. The panel features an XGA 1024 by 768-pixel resolution. LG assures that the new screen offers a paper-compatible reading experience. The company says that “As EPD gets thinner, lighter, and more durable with the introduction of plastic EPD, e-books will be able to offer certain unique benefits compared to smart devices and tablets, including reduced eye fatigue and more efficient electricity consumption in addition to lower prices.” While thin and light, the display was subjected to extensive stress testing of the display, said LG. Testers dropped it from a height of five feet and they whacked it with a urethane mallet. They said there was no breakage and no scratches. This might become a key selling point with LG’s plastic product, considering the dismay of some e-reader owners in the past who praise their e-readers for being light and easy on the eyes but also report disappointment over cracked or scratched screens. LG Display claims world’s thinnest TV panel This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. More information: Correction: 0.7mm thick (PhysOrg.com) — LG Display has set the production clock ticking for a plastic EPD (electronic paper display) product which in turn is expected to set e-book marketability fast-forward. In an announcement Thursday, Korea-based LG Display, which manufactures thin film transistor liquid crystal display, said it has already started up mass production of EPD for e-books. That leaves little guesswork as to the form factor and no suspicions that LG Display might instead be sending out vapor about a futuristic project that is still in R&D. © 2012 PhysOrg.com Explore further read more
More information: Chemical mapping of a single molecule by plasmon-enhanced Raman scattering, Nature 498, 82–86 (06 June 2013) doi:10.1038/nature12151AbstractVisualizing individual molecules with chemical recognition is a longstanding target in catalysis, molecular nanotechnology and biotechnology. Molecular vibrations provide a valuable ‘fingerprint’ for such identification. Vibrational spectroscopy based on tip-enhanced Raman scattering allows us to access the spectral signals of molecular species very efficiently via the strong localized plasmonic fields produced at the tip apex. However, the best spatial resolution of the tip-enhanced Raman scattering imaging is still limited to 3−15 nanometres, which is not adequate for resolving a single molecule chemically. Here we demonstrate Raman spectral imaging with spatial resolution below one nanometre, resolving the inner structure and surface configuration of a single molecule. This is achieved by spectrally matching the resonance of the nanocavity plasmon to the molecular vibronic transitions, particularly the downward transition responsible for the emission of Raman photons. This matching is made possible by the extremely precise tuning capability provided by scanning tunnelling microscopy. Experimental evidence suggests that the highly confined and broadband nature of the nanocavity plasmon field in the tunnelling gap is essential for ultrahigh-resolution imaging through the generation of an efficient double-resonance enhancement for both Raman excitation and Raman emission. Our technique not only allows for chemical imaging at the single-molecule level, but also offers a new way to study the optical processes and photochemistry of a single molecule. When a weak light beam of green color illuminates the molecule alone, the molecule is visible but lack of structural details (owing to the optical diffraction limit). However, when positioned under a tip, a much more intense and localized red-shifted light, produced by the plasmonic field, is acting on the molecule. The combination of both beams projects the vibrational fingerprints of the molecule into the emitting beam, chemically resolving the inner structure of the molecule with sub-nm resolution. Credit: Dong Xie and Rongting Zhou. Raman spectroscopy is where chemists shine a laser on a small group of molecules and then measure the light as it’s bounced back. The photons from the light source cause the molecules to vibrate and to interact with the bonds that hold molecules together causing a shift in their frequency—the scattering that results is unique for each type of molecule and thus allows for the method to be used as a means of identifying molecule types. Citation: Researchers use Raman spectroscopy and STM to allow chemical mapping of molecules to 1nm resolution (2013, June 6) retrieved 18 August 2019 from https://phys.org/news/2013-06-ramen-spectroscopy-stm-chemical-molecules.html Journal information: Nature Owing to the optical diffraction limit, a single porphyrin molecule cannot be resolved by conventional optical imaging with a green laser alone. However, when the molecule is positioned under a tip, a much more intense and localized red-shifted light, produced by the plasmonic field, is acting on the molecule. The combination of both beams projects the vibrational fingerprints of the molecule into the emitting beam, chemically resolving the inner structure of the molecule with sub-nm resolution. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. © 2013 Phys.org Top left: experimental map of an isolated porphyrin molecule for a given vibration frequency revealing the four-lobe pattern. Bottom left: theoretical calculation of the same molecular vibration showing its fingerprint. On the right: molecular structure of the porphyrin used in the experiment. Credit: Guoyan Wang and Yan Liang. Research team devises better method for mapping orbitals of molecules Left: Schematic diagram of tunneling-controlled tip-enhanced Raman scattering (TERS) in a confocal-type side-illumination configuration, in which Vb is the sample bias and It is the tunneling current. A laser light is focused into the nanocavity defined by the scanning tunneling microscope (STM) tip and substrate. The strong local plasmonic field generated by the incident laser causes the enhancement of Raman scattering from the single molecule underneath the tip. Top right: TERS spectrum acquired on the lobe; Bottom right: TERS map for the vibrational mode at about 817 cm-1 and corresponding line profile. Credit: Zhenchao Dong The researchers note their technique is still in the very early stages of development—thus far they’ve only been able to use it on one molecule—a ring-shaped porphyrin. The process they note, is difficult and can take weeks or months carry out making its application impractical at this point for general research efforts. Also it only works when the molecule under study is held in a vacuum and in a -200° C environment. If the technique can be fined tuned however, it will allow future chemists to identify the atoms in individual molecules. Such a tool could open the door to new ways to study molecules at the nano-scale level as well as the bonds that hold them together. (Phys.org) —A team of researchers working at China’s University of Science and Technology has succeeded in developing a chemical mapping technique capable of revealing the constituent atoms of a single molecule. In their paper published in the journal Nature, the team describes how they combined Raman spectroscopy with a scanning tunneling microscope (STM) to allow for chemical mapping of a molecule to a resolution of less than 1nm. A STM is a device that allows for creating images of materials at the atomic level—one of its unique features is the very tiny metal tip used at the point of scanning. In this new effort the researchers combined Raman spectroscopy with STM to allow for unprecedented levels of molecular mapping.Prior research has shown that when a STM tip is placed within nanometers of certain metals, plasmonic excitation occurs that when combined with Raman scattering can allow for mapping molecules to within 10nm. In this new research, the team has found that if the frequency of the plasmonic excitation is adjusted to match the molecular vibrations caused by photons from the laser light, the Raman signal is increased sharply, resulting in an ability to map the molecule being studied to less than 1nm. Explore further read more
Cooling and comb spectroscopy of gas-phase C60. A) Sublimated C60 vapor exits the oven source and enters a cryogenic cell, where it thermalizes via collisions with cold buffer gas introduced through an annular slit inlet plate surrounding the entrance aperture (see enlarged area). Mid-IR frequency comb light is coupled to an optical enhancement cavity surrounding the cell. The optical absorption spectrum is measured with a scanning arm Fourier transform spectrometer (not pictured). (B) The vibrational partition function (blue dashed line) and average vibrational energy (red solid line) increase strongly as a function of temperature. About 6 to 8 eV of vibrational energy must be removed per molecule to cool C60 from the initial oven temperature to below 150 K, at which point the vibrational partition function is approximately equal to unity. Credit: Science, doi: 10.1126/science.aav2616 , Nature Detailed views of portions of the measured IR band. (A) The R branch shows agreement between the expected intensity patterns from the simulation (black trace) and the measured spectrum (blue trace). The tie line above the spectrum indicates the lower state J value of each observed R(J) transition. (B) The Q branch region of the spectrum contains several features. The highest wavenumber feature is assigned as the Q branch of the 12C60 isotopologue. In the inset, the dashed line represents a fit to a simple quartic centrifugal distortion contour. The additional features at lower frequencies are likely due to the singly substituted 13C12C59 isotopologue. (C) These two portions of the P branch (blue trace) are representative of the disagreement with the zeroth-order simulation determined from parameters fitted to the R branch (black trace). The structure not captured by the simulation is evidence of nonscalar centrifugal distortion effects. Credit: Science, doi: 10.1126/science.aav2616. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Explore further Buckminsterfullerene is cage-like with a fused ring structure (truncated icosahedron) resembling a soccer ball. Composed of 20 hexagrams and 12 pentagons (60 vertices and 32 faces), the molecule contains a carbon atom at the vertices and a covalent bond along each polygon edge. The fullerene family members are investigated across a broad range of research disciplines for their appealing physical, chemical, quantum and biological properties. For instance, the total-quantum resolved spectroscopy of isolated C60 molecules are of longstanding interest. Such observations have been difficult to obtain thus far, since C60 molecules should be prepared in cold gas phase at sufficiently high densities. In a recent study, now published in Science, physicists Bryan Changala and colleagues report high-resolution, infrared absorption spectroscopy observations of C60 in the 8.5-micron spectral region (corresponding to 1180 to 1190 wave number). In the experiments, the team combined cryogenic buffer gas cooling and cavity-enhanced direct frequency comb spectroscopy to observe the quantum state-resolved rovibrational (rotational-vibrational) transition. Molecules usually expend more energy to vibrate than rotate, so a vibrational absorption band encompasses many concurrent rotational transitions, although they tend to blur when a molecule has more than a few atoms. Results of the study showed characteristic nuclear spin statistical intensity patterns, to confirm the indistinguishability of the 60 carbon-12 atoms. The rovibrational structures encoded further details of the molecule’s rare icosahedral symmetry. Changala et al. successfully cooled C60 fullerenes to obtain the rotational resolution within a C-C stretching band. The experimental success depended on careful optimization of argon buffer gas flow. The observed quantum-state resolved features can assist characterize fullerene-type compounds in exotic environments such as interstellar space. A central objective of chemical and molecular physics is to understand molecules as quantum mechanical systems. The complex internal dynamics of such systems evolve across wide energy and time scales, exhibited by a variety of electronic, vibrational, rotational and spin degrees of freedom. Since its original discovery, the unique properties of buckminsterfullerene (C60) have attracted intense research activity. Notably, the molecule (C60+) was identified as a constituent of the enigmatic diffuse interstellar bands, which are found in the spectra of reddened starlight in space. Structurally, the unique carbon cage architecture makes them an appealing subject in medicinal chemistry to derive potential therapeutic agents. Journal information: Science Buckminsterfullerene C60 was discovered by Kroto et al. in 1985. Following its discovery, infrared (IR) and 13C nuclear magnetic resonance (NMR) spectroscopy confirmed its caged icosahedral structure. The scientific understanding of the molecule was further advanced via subsequent spectroscopic and analytical techniques, including x-ray and electron diffraction, Raman and neutron scattering, matrix isolation IR spectroscopy and photoelectron spectroscopy. Combing light for tell-tale chemical fingerprints , Journal of Chemical Physics © 2019 Science X Network Spectroscopic patterns of the IR active vibrational band of 12C60 near 8.5 μm. (A) A simulated (sim.) spectrum (black trace) is compared to a measured spectrum of cold (blue trace) and hot (red trace) C60. The measured hot spectrum shows broad, unresolved absorption owing to many thermally occupied vibrational states. The cold spectrum exhibits sharp, well-resolved rotational structure from transitions out of the ground vibrational state. norm., normalized to peak absorption. (B) Rovibrational transitions between the ground vibrational state and the excited state. Credit: Science, doi: 10.1126/science.aav2616 Citation: Rovibrational quantum state resolution of the C60 fullerene (2019, January 7) retrieved 18 August 2019 from https://phys.org/news/2019-01-rovibrational-quantum-state-resolution-c60.html More information: P. Bryan Changala et al. Rovibrational quantum state resolution of the C60 fullerene, Science (2019). DOI: 10.1126/science.aav2616 E. K. Campbell et al. Laboratory confirmation of C60+ as the carrier of two diffuse interstellar bands, Nature (2015). DOI: 10.1038/nature14566 K. HEDBERG et al. Bond Lengths in Free Molecules of Buckminsterfullerene, C60, from Gas-Phase Electron Diffraction, Science (2006). DOI: 10.1126/science.254.5030.410 Xue-Bin Wang et al. High resolution photoelectron spectroscopy of C60−, The Journal of Chemical Physics (2002). DOI: 10.1063/1.478732 Spectroscopy has played a key role in the astronomical detection of C60 and its derivatives. However, to date, there were no reports on the rovibrational quantum state-resolved measurements of C60 molecules. The experiments reported by Changala et al., therefore establish C60 as the largest molecule and the only example of rare icosahedral symmetry for which a complete internal quantum state-resolved spectrum has been observed. The 8-5 µm vibrational band was targeted in the study since it is the lowest-energy IR active mode in the accessible wavelength region. In the experiments, a 950 K copper oven sublimated the solid C60 samples to generate gas-phase molecules with an average internal energy of 6-8 eV per molecule. The samples populated 1026 to 1030 vibrational quantum states. The hot molecules then flowed into a cell anchored to a cryogenic cold finger, where they were thermalized via collisions with cold buffer-gas atoms introduced to the cell. The physicists interrogated the cold-phase molecules using cavity-enhanced direct frequency comb spectroscopy (CE-DFCS) by coupling a frequency comb into a high-finesse optical cavity surrounding the cold cell to generate the long-wave IR (LWIR) frequency comb light centered near 8.5 µm. The intensity of each comb tooth transmitted through the cavity was read using a broadband scanning-arm Fourier transform interferometer. Changala and collaborators initially attempted to observe cold gas-phase C60 using low-pressure helium buffer gas conditions, similar to previous work, but could not yield a detectable absorption. The results suggested that a higher number of collisions and more efficient energy transfer per collision would be required to thermalize C60 to its ground vibrational state. As a result, a sufficiently dense, cold C60 sample was produced in the study by (1) increasing the buffer-gas mass by switching from helium to argon and (2) carefully optimizing the buffer gas flow as well as oven positioning relative to the inlet slit. The spectrum acquired at these conditions exhibited well-resolved rovibrational fine structure with narrow linewidths. The wide spectral bandwidth of the frequency comb allowed observation between the narrow and broad signals that covered the entire breadth of the observed vibrational band. The observed fine structure in the infrared spectrum provided fundamental details of the quantum mechanical structure of C60. The energies of the states were determined by effective rotational Hamiltonians for each vibrational state. The results also indicated exceptional examples of nuclear spin statistics at work. The scientists conducted experiments to obtain detailed views of the measured IR band. When detecting R branch transitions; where the rotational quantum number in the ground state was one more than the rotational quantum number in the excited state (i.e. ∆J = +1). The expected intensity patterns from the simulation agreed with the measured spectrum. The observed patterns were a consequence of quantum mechanical indistinguishability of the perfect icosahedral arrangement of the carbon nuclei making up 12C60. In the Q branch region of the spectrum, where the rotational Q number in the ground state was similar to the rotational Q number in the excited state (i.e. ∆J = 0), the researchers observed several features. They assigned the highest wavenumber feature as the Q branch of the 12C60 isotopologue in its ground vibrational state. The remaining features in the Q branch region were not definitively assigned, but the scientists believed they were derived from the singly substituted 12C5913C isotopologue. Although the natural abundance of 13C was only 1:1%, the 60 equivalent substitution sites on the molecule lead to a notably high 12C5913C: 12C60 ratio of about 2:3.While the qualitative appearance of the measured R and Q branch was consistent with the simulation, in the P branch, the results were in substantial disagreement. The P branch is where the rotational quantum number in the ground state is one less than the rotational quantum number in the excited state (i.e. ∆J = -1). The zeroth-order simulation failed to capture the position of the number of observed transitions. This was likely since the high-order centrifugal distortion terms were not included in the simulated spectrum. The described experiments conducted by Changala and co-workers point toward an exciting direction of fullerene research, due to the broad relevance of the molecules from space to medicine. The practical applications of buffer-gas cooling introduced in the study also established the possibility of experimental repeatability in the future. Additional work can use the vibrational, electronic or other spectroscopies on larger fullerenes such as C70. Experiments can also include endofullerenes wherein an atom or molecule is encapsulated in a closed fullerene cage, or even include pure 13C60 as a pristine example of a spin-1/2 network on a spherical lattice. Chemical and molecular physics with precision spectroscopy of such targets is a first step toward single quantum state preparation, prior to experimentally controlling large molecular systems. read more
Tea has always been an integral part of one’s life. India for the first time ever organised a tea carnival Chai Ho Jaye brought by the Indian Tea Association in collaboration with Tea Board of India on 23 August in the Capital. The two-day celebration was launched by Arun Narain Singh, Chairman, Indian Tea Association. The highlight of the occasion was a tea tasting ceremony by Krishan Katyal, Managing Director, J Thomas & Co Pvt Ltd who familiarised the audience with unique blends and properties of tea like Darjeeling Tea, Orthodox Assam and Nilgiri Tea, CTC and Green Tea in an interactive session. Also Read – ‘Playing Jojo was emotionally exhausting’NK Jain, Tea Scientist, was also present for an informative session on the health aspects of tea drinking. The carnival also gave an opportunity to witness live demonstration of tea inspired mocktails by mixologist, Kama. The show also featured activities conceptualised on infotainment related to tea include flash mobs, games and competitions. Speaking on the occasion Singh said, ‘This carnival is an initiative to connect the tea industry with our consumers. It will help us to create awareness as well as understand the consumer reaction. The array of activities is aimed to create a buzz that can sustain itself through social media interaction to carry the message of tea consumption further beyond the physicality of the event’. read more
Prakash Jha and Ajay Devgn are producing multiple films with the actor and director bringing out a sequel to Gangaajal with a female protagonist. Devgn played the lead in hit 2003 original, which was inspired by the blinding incident in Bhagalpur in 1979 and 1980.Jha, who has collaborated with the actor on films like Dil Kya Kare, Gangaajal, Apaharan, Raajneeti and Satyagraha, said Devgn is his mascot. ‘As a filmmaker life long in your career you keep looking for a mascot and Ajay Devgn is the one for me. He gave me hope and faith and we continued to grow with each other.
Reliance Industries will relinquish its Krishna Godavari basin gas discovery block, KG-D3, mainly because of operational restrictions placed by the Defence Ministry.RIL, which had made four consecutive gas discoveries with close to 500 billion cubic feet of in-place reserves in block, proposed immediate relinquishment, its minority partner Hardy Oil and Gas plc of UK said on Wednesday. Hardy said the block oversight panel headed by upstream regulator DGH on Tuesday considered RIL proposal. Without stating what the Management Committee (MC) decided, Hardy in a statement said the firm has agreed to the relinquishment proposed by the operator, RIL. Hardy holds 10 per cent stake in the block which is operated by RIL with 60 per cent interest. BP of UK has the remaining 30 per cent stake. “The proposal sets out that as per the government of India notification dated November 10, 2014, access restrictions have been imposed and the operator recommended the relinquishment of the block with immediate effect,” it said. RIL, it said, conveyed that the previously announced access restrictions imposed by the Defence Ministry rule out any further exploration/development activities in the impact zone area and inhibited the contractor from undertaking any further work and investment in the unrestricted area of the block due to anticipated increase in cost and risk. Also Read – I-T issues 17-point checklist to trace unaccounted DeMO cash”This untenable position was further compounded by the uncertainty of long-term natural gas pricing in India, following the government policy announced earlier in the year which imposed pricing at a significant discount to our expectation of regional market pricing,” Hardy said. The government in October announced a 33 per cent hike in natural gas price to $5.61 per million British thermal unit, much lower than $8.4 rate that the industry was expecting. Also Read – Lanka launches ambitious tourism programme to woo Indian touristsRIL-Hardy combine had in 2005 won the 3,288 sq km block KG-DWN-2003/1 (D3) in the fifth round of auction under New Exploration Licensing Policy. RIL sold 30 per cent out of its 90 per cent interest in the block to BP in 2011.”In 2012, the Directorate General of Hydrocarbons (DGH) informed the operator of restrictions imposed… these restrictions affect 38 per cent of the block (1,242 sq km affected out of 3,288 sq km of block area) with a number of prospects lying in this affected area.”The Defence Ministry restrictions introduced since October 2012, which were beyond the control of the contractor, the effect of which was to prevent the contractor from making any further progress, as these restrictions impact operations through the life-cycle of exploration, development and production,” Hardy said. read more