No abstract

The reflectivity and the transmission of InSb crystals (w-type) were measured between 20 and 200/x. The reflectivity curve has a sharp maximum at 54.6/i and the transmission curve shows a low transmission at the same wavelength due to lattice vibration of this crystal. The transmission curve shows a weak absorption at 28.3^ due to the overtone of that lattice vibration. The reflectivity curve shows another flat peak at longer wavelengths. The reflectivity minimum between these two peaks shifts from 160 to 72/* with increase of temperature from -35 to 130°C, and the maximum value of the flat peak increases with increase of temperature and is 80% at temperatures of 100°C or more.The index of refraction n and the absorption constant K were calculated in the region in which both the reflectivity and the transmission were measured. Using the values of n and K thus obtained, the concentration of free electrons N and their mobility b were obtained, using the theory of free electrons. Then n, K, and the reflectivity, R, were calculated for the region in which the transmission could not be measured. The values of R thus obtained agree well with the observed values. This shows that the theory of free electrons holds in InSb except in the region in which the effects of lattice vibration in this crystal are dominant.

No abstract

An investigation of the working conditions of an infra-red spectrometer of the recording type has resulted in techniques of operation which have increased the precision of the measurements attainable and has permitted an appraisal of the magnitudes of the variations in the resulting data which may still be expected. Included in this study is the remeasurement of the fine structure of certain of the absorption bands of CO2, NH3, and H2O. Measured with a grating instrument whose resolution was made to equal that of the prism instrument in each case, these data give 150 sharp absorption lines between 5μ and 15μ suitable for an empirical calibration of great accuracy.

The pure rotation spectra of HCl, DCl, HBr, and NH3 in the region from 40 to 140 microns as measured with an automatic-recording grating spectrometer are presented in tabular and graphical form. A photograph of a recorded spectrogram provides an indication of the quality of the data. A comparison of the experimental results with figures based on accepted values of the molecular constants shows substantial agreement.