From mobile phones and computers to television, cinema and wearable devices, the display of full colour, wide-angle, 3D holographic images is moving ever closer to fruition, thanks to international research featuring Griffith University ("Athermally photoreduced graphene oxides for three-dimensional holographic images"). Led by Melbourne's Swinburne University of Technology and including Dr Qin Li, from the Queensland Micro- and Nanotechnology Centre within Griffith's School of Engineering, scientists have capitalised on the exceptional properties of graphene and are confident of applications in fields such as optical data storage, information processing and imaging. "While there is still work to be done, the prospect is of 3D images seemingly leaping out of the screens, thus promising a total immersion of real and virtual worlds without the need for cumbersome accessories such as 3D glasses," says Dr Li. First isolated in the laboratory about a decade ago, graphene is pure carbon and one of the thinnest, lightest and strongest materials known to humankind. A supreme conductor of electricity and heat, much has been written about its mechanical, electronic, thermal and optical properties. "Graphene offers unprecedented prospects for developing flat displaying systems based on the intensity imitation within screens," says Dr Li, who conducted carbon structure analysis for the research. "Our consortium, which also includes China's Beijing Institute of Technology and Tsinghua University, has shown that patterns of photo-reduced graphene oxide (rGO) that are directly written by laser beam can produce wide-angle and full-colour 3D images. "This was achieved through the discovery that a single femtosecond (fs) laser pulse can reduce graphene oxide to rGO with a sub-wavelength-scale feature size and significantly differed refractive index. "Furthermore, the spectrally flat optical index modulation in rGOs enables wavelength-multiplexed holograms for full colour images." Researchers say the sub-wavelength feature is particularly important because it allows for static holographic 3D images with a wide viewing angle up to 52 degrees. Such laser-direct writing of sub-wavelength rGO featured in dots and lines could revolutionise capabilities across a range of optical and electronic devices, formats and industry sectors. "The generation of multi-level modulations in the refractive index of GOs, and which do not require any solvents or post-processing, holds the potential for in-situ fabrication of rGO-based electro-optic devices," says Dr Li. "The use of graphene also relieves pressure on the world's dwindling supplies of indium, the metallic element that has been commonly used for electronic devices. "Other technologies are being developed in this area, but rGO looks by far the most promising and most practical, particularly for wearable devices. The prospects are quite thrilling."
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Chemists' synthesis of silicon oxides opens 'new world in a grain of sand'
Gregory H. Robinson is the University of Georgia Foundation Distinguished Professor of Chemistry. The study, published April 20 in the journal ("Stabilization of elusive silicon oxides"), gives details on the first time chemists have been able to trap molecular species of silicon oxides.
Using a technique they developed in 2008, the UGA team succeeded in isolating silicon oxide fragments for the first time, at room temperature, by trapping them between stabilizing organic bases.
"In the 2008 discovery, we were able to stabilize the disilicon molecule, which previously could only be studied at extremely low temperatures on a solid argon matrix," said Gregory H. Robinson, UGA Foundation Distinguished Professor of Chemistry and the study's co-author. "We demonstrated that these organic bases could stabilize a variety of extremely reactive molecules at room temperature."
The columns, or groups, of elements of the periodic table generally share similar chemical properties. Group 14, for example, contains the element carbon, as well as silicon, the most carbon-like of all the elements. However, there are significant differences between the two. While the oxides of carbon, carbon dioxide and carbon monoxide are widely known, the molecular chemistry of corresponding silicon oxides is essentially unknown, due to the great reactivity of silicon-oxygen multiple bonds.
Silicon monoxide, on the other hand, has been described as the most abundant silicon oxide in the universe but, terrestrially it is only persistent at high temperatures, about 1,200 degrees Celsius. Naturally abundant silica ((SiO2)n) exists on Earth as sand--a network solid wherein each silicon atom bonds to four oxygen atoms in a process that repeats infinitely.
A light switch for superconductivity
A device that can be switched between insulating and superconducting states by irradiation with light has been developed by researchers from RIKEN and the Institute for Molecular Science (, "Light-induced superconductivity using a photoactive electric double layer"). The development could ultimately lead to more efficient superconducting microelectronics. 
Irradiating a thin crystal of κ-Br on a monolayer of spiropyran molecules with visible (left) and ultraviolet (right) light switches the κ-Br material between insulating and superconducting states due to the formation of an electric double layer. (© AAAS) The properties of solid materials can be dramatically altered by applying an electric field. In a common electronic component called a field-effect transistor, the flow of electrons through a semiconducting channel is controlled according to the strength of an internal electric field, which is created by applying a voltage to an insulating material—a dielectric. Higher field strengths provide more efficient conduction, but at very high fields the dielectric material begins to break down and conduct itself. To overcome this limitation, scientists have turned to the use of ionic liquids. When a voltage is applied to an ionic liquid, the charged particles in the liquid move to the surface of the channel material, creating an ‘electric double layer’ (EDL) that is not susceptible to dielectric breakdown. The high electric fields enabled by this technique have previously allowed researchers to convert the channel material from an insulator into a superconductor. So far, switching of the electric field has only been possible at relatively high temperatures because the ionic motion freezes at approximately 200 kelvin. Masayuki Suda and Hiroshi Yamamoto from the IMS and RIKEN, in collaboration with RIKEN’s Reizo Kato, have now shown that a light-sensitive molecule can be used to switch on a superconducting state at temperatures as low as 5 kelvin. The team replaced the ionic liquid with a single layer of spiropyran molecules, which are ionic under ultraviolet light and non-ionic under visible light. To test this strategy, they placed an organic crystal called ?-Br, which is known to have a superconducting state, on a single layer of self-assembled spiropyran molecules mounted on a thin oxide film. They confirmed that the resistance of the ?-Br switched from a high-resistance state under visible light to a low-resistance state when illuminated with ultraviolet light, due to the formation of an EDL (Fig. 1). “Even at low temperatures, ultraviolet light induces a zwitterionic structure in spiropyran molecules and a situation very similar to an EDL without an applied voltage, leading to superconductivity,” says Suda. “In this system, light induces the superconducting state by photoisomerization of the spiropyran molecules,” says Suda. “If we could get light to generate the superconducting carriers directly, other types of light-driven devices could also be possible.”
read more "A light switch for superconductivity"
Irradiating a thin crystal of κ-Br on a monolayer of spiropyran molecules with visible (left) and ultraviolet (right) light switches the κ-Br material between insulating and superconducting states due to the formation of an electric double layer. (© AAAS) The properties of solid materials can be dramatically altered by applying an electric field. In a common electronic component called a field-effect transistor, the flow of electrons through a semiconducting channel is controlled according to the strength of an internal electric field, which is created by applying a voltage to an insulating material—a dielectric. Higher field strengths provide more efficient conduction, but at very high fields the dielectric material begins to break down and conduct itself. To overcome this limitation, scientists have turned to the use of ionic liquids. When a voltage is applied to an ionic liquid, the charged particles in the liquid move to the surface of the channel material, creating an ‘electric double layer’ (EDL) that is not susceptible to dielectric breakdown. The high electric fields enabled by this technique have previously allowed researchers to convert the channel material from an insulator into a superconductor. So far, switching of the electric field has only been possible at relatively high temperatures because the ionic motion freezes at approximately 200 kelvin. Masayuki Suda and Hiroshi Yamamoto from the IMS and RIKEN, in collaboration with RIKEN’s Reizo Kato, have now shown that a light-sensitive molecule can be used to switch on a superconducting state at temperatures as low as 5 kelvin. The team replaced the ionic liquid with a single layer of spiropyran molecules, which are ionic under ultraviolet light and non-ionic under visible light. To test this strategy, they placed an organic crystal called ?-Br, which is known to have a superconducting state, on a single layer of self-assembled spiropyran molecules mounted on a thin oxide film. They confirmed that the resistance of the ?-Br switched from a high-resistance state under visible light to a low-resistance state when illuminated with ultraviolet light, due to the formation of an EDL (Fig. 1). “Even at low temperatures, ultraviolet light induces a zwitterionic structure in spiropyran molecules and a situation very similar to an EDL without an applied voltage, leading to superconductivity,” says Suda. “In this system, light induces the superconducting state by photoisomerization of the spiropyran molecules,” says Suda. “If we could get light to generate the superconducting carriers directly, other types of light-driven devices could also be possible.”
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