Browsing by Subject "Vibrational spectra"
Now showing 1 - 10 of 10
Results Per Page
Sort Options
Item A Vibrational Analysis of Acrylyl Chloride, 2-Chloroacrylyl Chloride, and Acrylic Acid.(Texas Tech University, 1974-08) Kennedy, John RiderNot Available.Item Curvilinear coordinate formulation for vibration-rotation-large amplitude internal motion interactions(Texas Tech University, 1986-08) Guan, YuhuaA theory for vibration-rotation-large amplitude internal motion interactions is developed using curvilinear coordinates for the vibrational degrees of freedom. An essential feature of the theory is our coordination of two transformations for the separation of vibration from rotation and vibration from the LAM, in zeroth order. Series expansion in the vibrational coordinates is used to obtain the full vibration-rotation-LAM Hamiltonian. A Van Vleck perturbation approach is used to obtain the effective rotation-LAM Hamiltonian for the molecule in the nth vibrational state. Reduction of the effective Hamiltonian has been made to (1) the zero angular momentum state of the molecule, (2) the zeroth order rotation-LAM Hamiltonian, and (3) the usual vibration-rotation Hamiltonian when the LAM takes on a small amplitude. The theory is applied to the water molecule treating the bending mode as the LAM. Fourier sine functions are used as the basis for the bending mode, harmonic oscillation functions for the two stretching modes, and Wang functions for the rotational motion. Using Hoy-Mills-Strey and Hoy-Bunker force constants and molecular geometry, the vibration-rotation- LAM energy levels for the water molecule have been calculated. The HMS constant yields better vibration-bending results and the HE constants better rotational results.Item Hindered internal rotation fine structure of the 3 micron vibration-rotation spectra of CH3SH(Texas Tech University, 1968-08) Varnell, Gilbert LynnNot availableItem Kinetic and spectroscopic isotope effects in carboxylic acids(Texas Tech University, 1981-05) Liang, Chin-kang JimNot availableItem Raman study of liquid methyl iodide and methyl fluoride(Texas Tech University, 1986-08) Zyung, TaehyoungThe DqukJs, CH3I and CH3F, were studied using a Raman spectrometer. The polarized and depolarized components of the V2 and V3 bands of CH3I were measured in the whole range of the temperature of the liquid. The recorded spectra were Fourier transformed to provide vibrational autocorrelation functions and memory functions. The vibrational autocorrelation functions and the experimental memory functions were analyzed by the methods of a memory function procedure and an autoregressive analysis, respectively. The Raman spectra of neat liquid CH3F were obtained as a function of temperature and the spectra in the dissolved state were also obtained. The spectra were explained qualitatively by using some theoretical models arid densities of states were calculated classically with a simple theoretical model in order to be compared with the observed spectra.Item Structural and vibrational properties of N, N pairs, and [N,H] complexes in silicon(Texas Tech University, 2004-08) McAfee, Jason LFirst-principles molecular-dynamics simulations are used to predict the structures and binding energies of interstitial nitrogen (Ni), substitutional nitrogen (Ng), the Njself- interstitial complex, the {Ni,Ni}, {Ni,Ns} = {N2,V}, and {Ng, N J = {N2,V2} pairs (V is the vacancy). The interactions of N with H in Si are studied and the properties of several {N, H} complexes predicted. The dynamical matrices yield many new local and pseudo-locfil vibrational modes associated with the impurities and their Si nearest-neighbors. The unidentified (N, H}-related infra-red absorption line reported by Pajot et al. is assigned to the {Ng, H} complex.Item Vibrational analysis and ab initio studies of propiolic acid(Texas Tech University, 1987-08) Ndip, Edmund Moses NsoA vibrational analysis and ab initio studies of propiolic acid have been carried out in a two part study. In the first part, infrared matrix isolation spectra of propiolic acid isolated in solid argon, carbon monoxide, nitrogen and neon at 11-35K have been recorded in the range 4000 - 400 cm^-1. Spectra were also recorded for the isotopically labeled O and H isotopomers isolated in argon and nitrogen matrices. Spectra have been interpreted using isotopic splitting patterns, correlations with spectra of related molecules, and MO normal coordinate analysis at the ab initio (6-31G* basis set) level and semi-emperical MINDO / 3 level using standard basis set. Computational studies using MINDO / 3 and GAUSSIAN 82 have been carried out to determine geometries, energies, dipole moments, rotational constants, vibrational frequencies, force constants, and one-electron properties. Comparisons have been made with experimental data to check the accuracy of computed molecular parameters. Various unimolecular decomposition channels have been investigated and possible bimolecular decomposition channels postulated. The computed structures and energies of various intermediates have been determined. The internal rotation (torsional) barrier for hydroxyl group relative to the C-0 bond has been determined at various levels and the conversion from the cis to trans conformer has been identified as a prerequisite for some decomposition channels.Item Vibrational analysis of molecules undergoing large amplitude internal motions(Texas Tech University, 1974-08) Cress, Daniel HuggOne of tbe primary efforts of investigators of molecular properties has been to determine the forces hindering internal motions in molecules. Molecules are bound by electronic interactions among the atoms and therefore a complete quantum mechanical solution to the problem should determine the force field once the atoms in a particular molecule are specified. However, the complications of this approach have lead to serious difficulties for most molecules. A more empirical method has been quite successful in determining the molecular potential energy along certain vibrational paths and for particular molecular geometries. For many molecules the intramolecular forces binding tbe atomic nuclei are such that the vibrational motions of the nuclei are restricted to small amplitude. The potential energy can then be expanded about the equilibrium configuration in a Taylor series. The potential energy is determined through the quadratic term of the series by adjusting the potential energy so that the frequencies obtained by normal mode analysis agree with experimental values. Anharmonic corrections have been obtained for many molecules by analysis of the deviations from the normal mode approximation.Item Item Vibrational studies of hydrogen fluoride(Texas Tech University, 1982-05) Hamill, Delphia FrancineNot available