Orientation optical

As a probe of lattice vibrations, Raman spectroscopy is very sensitive to intrinsic crystal properties and extrinsic stimuli, especially in semiconductors. It may be employed to study crystal structure and quality, crystal orientation, optical interactions, chemical composition, phases, dopant concentration, surface and interface chemistry, and local temperatme or strain. As an optical technique, important sample information may be obtained rapidly and nondestructively with minimal sample preparation. Submicron lateral resolution is possible with the use of confo-cal lenses. These features have made it a vital tool for research labs studying semiconductor-based technologies. They also are increasingly important for the study of semiconductor NWs fabricated by both top-down and bottom-up approaches since many of the common characterization methods used with bulk crystals or thin films cannot be applied to NWs in a direct manner. 

Kim, J. C., Cakmak, M. and Zhou, X., Effect of composition on orientation, optical and mechanical properties of biaxially drawn PEN and PEN/PEI blend films. Polymer, 39, 4225-4234 (1998). 

Mao XJ, Wang SW, Shimai S, Guo JK (2008) Transparent polycrystalline alumina ceramics with orientated optical axes. J Am Ceram Soc 91 3431-3433... 

Spectroscopic quadrupole moments can be determined by many experimental methods differential perturbed angular distribution of j rays following nuclear reactions, low temperature nuclear orientation, optical spectroscopy. Coulomb excitation reorientation, different methods of laser spectroscopy, hyperfine spKtting of spectrum lines in inhomogeneous electric field, etc. 

In [133], devoted to the orientational optical nonlinearity of liquid crystals, some additional effects observed in cholesterics are considered the giant optical bistabilty, grating orientational nonlinearity, pitch change due to the direct action of light and to the thermal effects, hysteresis, and optical bistability and nonlinearities connected with absorption. Here we cite some... 

X.J. Mao, S.W. Wang, S.Z. Shimai, and J.K. Guo, Transparent Polycrystalline Alumina Ceramics with Orientated Optical... 

Laser-Induced Orientational Optical Nonlinearities in Liquid Crystals... 

Tabiryan, N. V., A. V. Sukhov, andB. Ya. ZePdovich. 1986. The orientational optical nonlinearity of liquid crystals. Mol. Cryst Liq. Cryst 136 1. In this review article, various optical field-nematic axis configurations and the associated nontinearities are discussed. 

In some nematic liquid crystals (e.g., MBBA or azoberrzene liquid crystals), theories and experiments have shown that, when photoexcited, the molecules will undergo some stmctural or conformational changes (from trans state to cis state) and will exhibit unusually large orientational optical nonlinearities. Such electronic-oiientational nonlinearities are discussed earlier in Chapter 8. 

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