Infrared absorption spectra of HC1 and HBr, suspended in solid argon, krypton and nitrogen, were recorded in order to obtain information on intermolecular forces. SO₂ in argon and nitrogen, and CO in argon were also studied. The spectra were observed in the temperature range from liquid helium temperatures up to the melting point of the matrix. The halogen acids gave more complicated spectra in the noble gas matrices than in nitrogen. This has been correlated with the different thermal properties of the matrix materials. Matrix to solute ratios from 100 to 800 to 1 were used and evidence was found for solute-solute interactions, arising from incomplete isolation of solute molecules at the lower ratios. During the warm-up period at the end of an experiment, additional peaks appeared in the spectra. It is suggested that these new peaks were due to clusters of solute molecules produced by diffusion of the solute through the lattice. Semi-empirical calculations were carried out to estimate shifts of vibrational frequencies of the trapped molecules. From these calculations it was concluded that repulsive intermolecular forces play an important part in determining the magnitude, and direction of the shifts. A first order perturbation calculation was made, using a Lennard-Jones' potential, to determine the effect of the matrix on the rotational energy levels of a trapped molecule. Spectra of the clathrate-hydrates of SO₂, H₂S and krypton were recorded at liquid nitrogen temperatures, and the SO₂ hydrate was studied in the temperature range from 4° to 120° K. The spectrum of the water skeletal vibrations exhibited several interesting features. The assignment of the 1600 cmˉ¹ and 2200 cmˉ¹ peaks to v₂ and v₂ + vR was confirmed and a new peak at 2410 cmˉ¹ was observed. A lattice mode in the spectrum of the S0₂ hydrate was observed in combination with V₃ of SO₂. / Science, Faculty of / Chemistry, 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

The optical properties of the 10.4 K organic superconductor, κ-{BEDT—TTF)₂[CU-(NCS)₂], are the subject of this thesis. This organic superconductor is a crystalline solid consisting of planes of BEDT-TTF molecules separated by planes of Cu{NCS)₂ anions. The arrangement of molecules results in electrical two-dimensionality, with high conductivity within the planes of BEDT-TTF molecules and poor conductivity in the perpendicular direction. Until the recent discovery of an organic superconductor with TC = 11.5 K, the 10.4 K transition of (BEDT-TTF)₂[Cu(NCS)₂] was the highest in the class of organic metals. Optical properties of superconductors have played an important role in analysis of their unusual properties. Using single crystals of (BEDT—TTF)₂[Cu(NCS)₂] and light polarized within the highly conducting plane, I have measured both specular reflectivity and bolometric absorption over a wide region of the infrared spectrum. The reflectivity measurements cover most of the far and mid-infrared for both protonated and deuter-ated compounds, with sample temperatures between 300 K and 6.5 K. The resulting spectra show contributions from electronic interband transitions, intraband transitions, and molecular phonon vibrations. A search for the superconducting energy gap was undertaken using the bolometric technique to measure the sample absorption at far-infrared energies. These measurements were performed at temperatures below Tc and cover the part of the spectrum where condensation of electrons into superconducting Cooper pairs should be directly observable optically. On other materials, measurements in this part of the spectrum have directly revealed the binding energy for the superconducting electron pairs, and have been instrumental in showing that details of the electron-phonon interactions are very important in superconducting systems. In the spectra which we have measured, any effect of the superconducting transition is overwhelmed by other contributions to the absorption in the far-infrared energy region. / 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

The microwave spectra of three unstable molecules, bromine isocyanate (BrNCO), iodine isocyanate (INCO), and bromine thiocyanate (BrSCN), have been observed and analyzed in the frequency range 16-54 GHz. The infra-red spectrum of aminodifluoroborane (BF₂NH₂) has been investigated in the region 3700-400 cm⁻¹, and one band, the 2¹₀ vibrational band has been recorded at a resolution of 0.004 cm⁻¹, and the rotational structure analyzed. BrNCO: BrNCO was generated from the flow reaction of Br₂ with silver cyanate. The spectra of two isotopic species were observed: ⁷⁹BrNCO and ⁸¹BrNC0. They contain strong a-type transitions as well as some weaker b-type transitions which could not initially be assigned. In addition, the transitions show both Br and N quadrupole hyperfine structure. A novel method has been developed which uses perturbations in the Br structure to evaluate all the rotational constants, as well as the Br quadrupole tensor, entirely from a-type R branch transitions using a global least-squares fitting programme. This has allowed some b-type transitions to be assigned. The molecule has been shown to be planar and a partial r₀ structure was determined. The principal values of the Br quadrupole tensor have been evaluated and have provided some information about the type of bonding involved in the Br-N bond. INCO: INCO was observed in the flow reaction of I₂ with silver cyanate. Many strong a-type transitions were observed as well as some very weak b-type transitions. These transitions showed I and N quadrupole hyperfine structure; many perturbations in the I structure were observed. The method developed in the analysis of the spectrum of BrNCO using such perturbations to obtain otherwise unobtainable rotational constants was extended to include centrifugal distortion constants. The planarity of INCO has been confirmed and a partial r₀ structure was determined. The principal values of the I quadrupole tensor have been evaluated and have provided some information about the type of bonding involved in the I-N bond. BrSCN: BrSCN was generated in the flow reaction of Br₂ with silver thiocyanate. The spectra contained both a- and b-type transitions, all of which showed Br quadrupole hyperfine structure. The rotational constants and all five quartic centrifugal distortion constants were obtained for two isotopic species: ⁷⁹BrSCN and ⁸¹BrSCN. The rotational constants confirm the thiocyanate configuration, and a partial r₀ structure has been obtained. Also, the principal values of the Br quadrupole tensor were evaluated which show that the Br-S bond is essentially covalent, with small amounts of π and ionic character. BF₂NH₂ : BF₂NH₂ was generated by heating solid BF₃ NH₃. The wavenumbers of 7 of the vibrational fundamentals have been obtained, and from the analysis of the 2¹₀ band, an accurate set of rotational and quartic centrifugal distortion constants of the ground vibrational state have been obtained and the rotational and quartic centrifugal distortion constants of the 2¹ level have been evaluated. Also a Coriolis type perturbation was observed, probably due to the combination level v₇ + v₁₁ , which has provided an estimate of the wavenumber of the v₁₁ fundamental which has not yet been observed. / Science, Faculty of / Chemistry, Department of / Graduate

Some unstable gaseous molecules, cobalt oxide (CoO), niobium nitride (NbN) and aminoborane (NH₂BH₂), were studied by high resolution optical spectroscopy. A portion of the "red" system of CoO, from 7000 Å to 5800 Å, was measured using laser induced fluorescence techniques. Three bands of the system, with origins at 6338 Å, 6411 Å and 6436 Å, were rotationally analyzed. The lower levels of these parallel bands are the Ω = 7/2 and 5/2 spin-orbit components of a ⁴∆i electronic state. Available evidence indicates that this is the ground state of the molecule; its bond length is 1.631 Å. This work completes the determination of the ground state symmetries for the entire series of first row diatomic transition metal oxides. The hyperfine structure in the ground state is very small, supporting a σ²δ³π² electron configuration. The upper state, assigned as σδ³π²σ*, has large positive hyperfine splittings that follow a case (aβ) pattern; it is heavily perturbed, both rotationally and vibrationally. The sub-Doppler spectrum of the ³Φ₋³∆ system of NbN was measured by intermodulated fluorescence techniques, and the hyperfine structure analyzed. Second order spin-orbit interactions have shifted the ³Φ₃₋³∆₂ subband 40 cm⁻¹ to the blue of its central first order position. The perturbations to the spin-orbit components were so extensive that five hyperfine constants, rather than three, were required to fit the data to the case (a) Hamiltonian. The ³∆₋³Φ system of NbN is the first instance where this has been observed. The magnetic hyperfine constants indicate that all components of the ³∆ and ³Φ spin orbit manifolds may be affected, though the ³∆ state interacts most strongly, presumably by the coupling of the ³∆₂ component with the ¹∆ state having the same configuration. The Fermi contact interactions in the ³∆ substates are large and positive, consistent with a σ¹δ¹ configuration. In the ³Φ state the (b + c) hyperfine constants are negative, as expected from a π¹δ¹ configuration. The ³∆ and ³Φ bond lengths are 1.6618 Å and 1.6712 Å, respectively, which are intermediate between those of ZrN and MoN. The Fourier transform infrared spectrum of the V7 BH₂ wagging fundamental of NH₂BH₂ was rotationally analyzed. A set of effective rotational and centrifugal distortion constants was determined, but the band shows extensive perturbations by Coriolis interactions with the nearby V5 and V11 fundamentals. A complete analysis could not be made without an analysis of the V5-V7-V11 Coriolis interactions, which is currently not possible because the very small dipole derivative of the V5 vibration has prevented its analysis. / Science, Faculty of / Chemistry, Department of / Graduate