Photopolymerizable recording media for threedimensional holographic optical memory

131 1 The development of information technologies requires the creation of new information storage media, since the information capabilities of magnetic media appear to be reaching a limit now Along with further improvement of magnetic media, optical disks (ODs), which substantially extend the capabilities of information technologies, find widespread application At present, three types of OD are used, which are designed for (1) only multiple reading of information recorded earlier (compact disks, or CD), (2) single information recording in a personal computer and multiple reading of information recorded (WORM OD), and (3) multiple processes of information recording, erasing, and reading in a personal computer (WERM OD). The considered OD types find progressively increasing application. However, their limited information capacity becomes a retarding factor. This is due to the fact that only one or two surfaces of the information storage units are used for information recording. At present, ODs are actually two-dimensional (2D) storage systems. Further progress in information technologies calls for development of three-dimensional (3D) OD. In this respect, investigations are performed aimed at designing multilayer OD structures (with more than 100 layers) with the use of a nonlinear two-photon process of bit-by-bit information recording and retrieval with an information capacity of more than 1 Tb cm -3 1 E-mail: [email protected] An alternative way of realization of three-dimensional information carriers is the use of the holographic method of information recording in a thick photosensitive medium Photosensitive media based on photopolymerization processes of organic compounds referred to as photopolymerizable or photopolymer materials (PPM) are the most suitable and promising for the fabrication of holographic CDs with an ultrahigh data storage capacity In spite of the theoretical possibility of using these materials to manufacture ODs of ultrahigh data storage capacity, which was shown by investigations, it is obvious now that they need improvement, especially in the line of elimination of recording-layer shrinkage during hologram writing To comprehend some specific requirements imposed on holographic recording media, we will briefly consider the holographic parameters that determine the possibility of their application. Holograms are interference patterns that appear in a photosensitive layer as a result of interference of reference and object laser beams. The reference beam is used thereafter to retrieve information from the holo- Abstract -The development of investigations in recent years on photopolymerizable recording holographic media for using as photosensitive layers of holographic optical disks, which satisfy the conditions for the application in archive optical memory is analyzed. It is shown that the main emphasis in the development of photopolymerizable holographic recording media is put on the improvement of their component composition. Formulations that permit joint radical and cationic photopolymerization were designed for thermally stable holographic recording. The holographic characteristics achieved for these media ensure the fabrication of singlelayer optical disks 150 mm in diameter with the information capacity of 200 GB instead of 5 GB for modern optical disks. Ways of improving photopolymerizable holographic recording media for the manufacture of optical disks with an information capacity of more than 1 Tb cm -3 are considered. REVIE

Synthesis and photoluminescence properties of zinc(II) complexes with salicylaldehyde hetarylhydrazones

New zinc complexes of the salicylaldehyde benzazolyl- and pyrimidinylhydrazones were synthesized. Study of photophysical properties of the hydrazones and their complexes in solution showed that their structure and the luminescence intensities depend on the nature of the heterocyclic fragment included to the molecule. © 2013 Pleiades Publishing, Ltd

Synthesis, structure, and photochemical properties of hetarylaldehydes benzimidazolyl-2-hydrazones

New benzimidazolyl-2-hydrazones of 2-furaldehyde, thiophene-2-carbaldehyde and pyridine-2-carbaldehyde were synthesized and their structure was studied by 1 ? NMR and X-ray analysis. Photochemical properties of these compounds and of benzothiazolyl-2-hydrazones of 2-furaldehyde, thiophene-2-carbaldehyde and pyridine-2-carbaldehyde in solutions were investigated. The process of phototransformation is determined by the nature of the aldehyde fragment of hydrazones. © Pleiades Publishing, Ltd., 2010

Laser photolysis study of 1-aryl-3-methyl-5-(benzothiazole-2-yl) formazan phototransformation

Photochromism of 1-aryl-3-methyl-5-(benzothiazole-2-yl)formazans in toluene has been investigated by the laser flash photolysis method. It was established that the photochromic transformations involve the triplet state of the initial chelate form of formazans. The intermediate short-lived products of phototransformation were detected that could be related to one of the conformers or to the tautomers of the formazan molecule. © Pleiades Publishing, Inc., 2011