Laser-induced diffraction patterns in germanium diselenide amorphous films.
We report the characterization of changes produced on germanium diselenide amorphous semiconductor thin films by a focused He-Ne laser beam. The diffraction pattern produced by the laser spot on the sample is studied as a function of the intensity and the irradiation time. At low intensities the state of polarization of the incident beam generates an asymmetry in the induced diffraction pattern. Moreover, if the polarization of the incident beam is rotated, the corresponding asymmetry rotates as well. These results show the difference between thermal and electromagnetic effects on the material. This system may be used as a high density recording medium.
Laser-induced optical anisotropy in self-supporting amorphous GeSe2 films
A comprehensive study of laser induced optical anisotropy in amorphous GeSe2 films is presented. This anisotropic structure of the amorphous network can be reoriented reversibly by changing the incident-beam polarisation. A model is constructed that accounts for experimental findings, in particular for the logarithmic time development of the laser-induced anisotropy.
Optical rotatory dispersion and absolute configuration—III
Abstract Optical rotatory dispersion measurements on pyrrolidine, piperidine, and tetrahydro-isoquinoline alkaloids indicate that the absolute configuration of the α-asymmetric center may be assigned directly from the dispersion curve, provided either that the nitrogen atom is not protonated, or that the compound contains a chromophore absorbing above 200 mμ.