In boron-doped silicon, optical absorption takes place through the excitation of bound holes from the ground state to excited states. This leads to a line spectrum. Due to a lack of sufficient resolution and a failure to make proper allowance for line distortion by the finite spectrometer slit width previous authors gave a misleading picture of the low temperature half-width, the temperature dependence of this half-width, and the onset of concentration broadening at low temperatures. New experimental data are explained by introducing the mechanism of statistical Stark broadening due to ionised impurities, and by modifying Baltensperger's (1953) theory for concentration broadening. At low impurity concentration the width is attributed to phonon broadening (Barrie and Nishikawa 1962) and internal strains (Kohn 1957). / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The absorption of polarized infrared radiation by single crystals of barium formate has been recorded between 4000 and 500 cm⁻¹. Factor group splitting has been observed for molecular modes and for some of the overtones and combinations. Lattice mode frequencies are inferred from combinations with molecular modes. The infrared spectrum of polycrystalline lead and sodium formate, and of aqueous barium formate has been similarly recorded and compared with that of crystalline barium formate. The nuclear magnetic resonance spectrum of barium formate has been recorded, and a discrepancy between the theoretical and experimental second moment indicates that a previously proposed crystal structure is incorrect. However, an X-ray and infrared study of a single crystal confirm that the factor group of barium formate is P2₁2₁2₁ and that there is no degradation of the crystal symmetry due to a possible distortion of the C-H bond of the formate ion. It is concluded that the coordinates of the carbon and oxygen atoms are incorrect in the original crystal structure determination. The nuclear magnetic resonance spectrum of lead formate also indicates that the crystal structure of this compound is in error, but no attempt is made to elucidate the correct structure. / Science, Faculty of / Chemistry, Department of / Graduate

The infrared absorption spectrum of carbon disulphide in the vapour state has been remeasured in the region from 2 to 15 microns. A total of six bands were measured in the region less than 15 microns. They were located at 3.38, 3.51, 4.29, 4.58, 6.52, and 11.4 microns. The measurements were made with a Perkin-Elmer spectrometer with a D.C. breaker type amplifier and Brown recorder. Cell lengths up to 100cm were employed. The wave lengths of the observed absorption hands are given in a table, and graphs are shown of the percentage transmission over the wave drum setting of the spectrometer. Phase shifting thyratron circuits, suitable for the accurate control of conditions of the absorbing media, are discussed. Of interest are the measurements of the structure of the Ʋ ₃ band at 1535 cmˉ¹. The side band located at the long-wave length side of the Ʋ₃ band is due to the isotopic effect produced by C¹³. The bands obtained are such as to support the conclusion that carbon disulphide is a linear triatomic molecule. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

This paper deals with the problem of setting up an infrared spectrometer and recorder under suitable conditions, and in applying the instrument to the absorption spectrum of CS₂ in the vapor phase. Six absorption bands, corresponding to the fundamental vibration V₃ at 1535 cm⁻¹, the difference band V₃ - V₁, at 877 cm⁻¹, and the four combination bands V₁ + V₃ at 2185 cm⁻¹, V₃ + 2V₂ at 2332 cm⁻¹, V₃ +2V₁ at 2838 cm⁻¹, and V₁ + V₃ + 2V₂ at 2959 cm⁻¹ have been examined. Using this value for V₃, a better agreement between the force constant of the C S bond, calculated from V₃, with that calculated from V₁, is obtained. The work is to be continued. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Details are given of the design and construction of a single-beam, three-prism, infra-red spectrograph, to be used in the near infra-red region 0.7μ to 2.5μ for the purpose of examining fine structure in molecular bands in this region. The problems encountered and methods of solution are explained. Details are presented of the optical and mechanical design of the instrument. The radiant energy transmitted by the spectrograph falls on a PbS photoconducting cell after being chopped at 900 c.p.s. The resulting signal is amplified in a tuned amplifier and, after rectification, is recorded on a Brown recording potentiometer. Details of detector and amplifier are presented. The method of calibration is explained and the performance of the instrument in practice is assessed by consideration of typical spectra taken with the final assembly. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

An infrared Fourier spectrophotometer has "been set up in the solid state laboratory of the University of British Columbia. A cryostat has been built and adapted to the spectrometer. A computer program to analyze the data and plot the spectrum has been written. As a demonstration of the system's capability, the transmission spectrum from 40 cmˉ¹ to 330 cmˉ¹ of boron doped silicon was obtained for the sample at liquid helium temperature. This spectrum was compared to earlier work done by Colbow in the region 240 cmˉ¹ to 330 cmˉ¹. A spectrum of boron and indium doped silicon was Investigated in the hope of finding Bˉ and In⁺ ionized centres. These were not found at the impurity concentrations and temperatures used. A transmission spectrum of intrinsic silicon at liquid helium temperature was obtained for the region 40 cmˉ¹ to 330 cmˉ¹ A comparison of the above spectra suggests that the low energy tail of the boron doped and boron and indium doped samples is due to a frequency dependent value of reflectivity as Is seen from the spectrum for intrinsic silicon. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

A variable temperature dewar has been designed and built at the solid state laboratory of the University of British Columbia for infra-red absorption experiments at low temperatures. The dewar features a rotatable sample holder which brings any one of three samples into the light beam for comparison measurements. A removable tail section permits easy access to the samples. The dewar has been successfully operated over the 4°K to 50°K range. It can maintain sample temperatures to within 1°K for periods up to two hours. Approximately ten minutes is required to achieve any desired temperature in the operating range. The construction and calibration of a copper vs. constantan thermocouple is described. The thermocouple was used to measure the sample temperatures to an accuracy of about 1°K. Temperature variations of a few tenths of a degree could be detected. As a demonstration of the dewar's capabilities, an experiment was performed to measure the line width dependence of hole transitions from the ground state of the P3/2 band to the first excited state in the P1/2 band in boron doped silicon. The experiment showed that the line broadening starts at about 20°K and increases at higher temperatures. Several methods of improving the performance of the dewar are suggested. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

No description available.

No description available.

No description available.