The photon drag effect in semiconductors are reviewed briefly. The photon momentum is transferred to free carriers in the course of light absorption under an intense laser beam, causing an induced current or a voltage across the sample. The photon drag effects through intra and inter-band transitions, and excitation from impurity levels have been observed in Ge, Si, GaAs and Te. The relaxation of the effect is limited by the momentum relaxation time of free carriers. An inherent high speed response of the photon drag effect allows application to detectors for very short infrared light pulses.
This paper describes a new method of atomic absorption spectrometry using a Zeeman modulation technique. In this method, an external a. c. magnetic field is applied on sample atoms in a flame, causing a Zeeman modulation on the aborption line of the atoms. Absorption signals caused by the pertinent atoms are found to be selectively modulated, whereas the background absorption signals caused by molecular absorption, scattering and other origin are not in the least affected. A d. c. signals which indicates the true atomic density is obtained by a phase sensitive detection of the absorption signals. Experimental and theoretical calibration curves (Cd concentration 0.1-2 μ/ml) for the Cd 2, 288 Å line are in good mutual agreement. Experimental curves (Cd concentration 2-1, 000 μ/ml) for the Cd 3, 261 Å line are also given and it is shown that the detected signals are proportional to the true cadmium concentrations within the indicated ranges.
The liquid phase epitaxial growth technique to obtain numbers of high quality garnet films with closely controlled magnetic properties is discussed. The growth of uniform films with a low density of magnetic defects is performed under the axial rotation of substrate with optimum rotation speed and by using a carefully cleaned substrate. In order to suppress the fluctuation of bubble properties, the growth temperature and time for the next run are modulated quickly using the bubble collapse field and film thickness of the grown film. By this technique, the bubble properties of 30 mm dia. SmY-garnet films grown in succession in a 768g melt are controlled within ±1% with a reproducibility of more than 65%.
Electro-optical Properties of liquid crystal displays of the twisted nematic field effect type (TN-FEM) have been systematicaly studied. It has been clarified that in application to display devices the vital points are; (1) removing the disclinations which result from the degeneration of alignment for the purpose of giving a certain view-angle to the devices ; (2) the view angle should be directed to the observer. In the multiplex driving scheme of the TN-FEM devices, the response properties (both τr and τd) are proportional only to η/κ (viscosity/elasticity), so the liquid crystal system should be selected by a different criteria from those of the static driving scheme.
The substrate-surfaces treated with carboxylatochromium complexes are shown to produce homeotropic molecular alignments of three different kinds of liquid crystals, i.e., nematic (MBBA), smectic (BBBA), and largepitch cholesteric (l wt.% CC in MBBA) fluids. The complexes used are tetrachloro-μ-hydroxo-μ-carboxylatodichromium (III) having myristato and perfluorononanoato as the carboxylato ligand, respectively. The orientation effect of the complexes on liquid crystals is briefly discussed.