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Title:Temperature and High Pressure Light Scattering Studies of Linear Triatomic Molecules in the Liquid State (Reorientation, Dephasing, Collision-Induced)
Author(s):Hegemann, Bruce Edwin
Department / Program:Chemistry
Discipline:Chemistry
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):Chemistry, Physical
Abstract:Light scattering lineshape analysis provides a powerful experimental probe of molecular dynamics in the liquid phase. This thesis consists of temperature and high pressure studies of collision-induced scattering in carbon disulfide and carbonyl sulfide, and reorientational motion and vibrational relaxation in carbonyl sulfide.
Quantitative results for the separate temperature and density effects on collision-induced scattering (CIS) lineshapes for liquid CS(,2), are presented for the depolarized Rayleigh scattering (DRS) and (nu)(,1), (nu)(,2), and (nu)(,3) mode Raman scattering lineshapes. Three distinctive CIS lineshape regions are observed and interpreted qualitatively in terms of available theoretical models. The results generally support the multipole-induced-dipole interaction mechanism for all CIS lineshapes at all frequencies.
The rotational motion of neat liquid OCS under its own vapor pressure is investigated through anisotropic Raman lineshape studies of the symmetric (nu)(,1) C = S stretching mode as a function of temperature. The contribution of CIS to the (nu)(,1) mode rotational lineshape is examined. The Raman (nu)(,2) and (nu)(,3) and DRS lineshapes of neat liquid OCS under its own vapor pressure are also investigated as a function of temperature. Results are compared when possible to previous results on the (nu)(,1) mode of OCS and the DRS lineshapes of CS(,2). The relationships observed are discussed and compared to theoretical predictions.
The Rayleigh and anisotropic Raman (nu)(,1) lineshapes of liquid OCS are investigated as a function of pressure and temperature. The results are found to support the conclusions for CIS and reorientational motion behavior obtained in the previous studies of CS(,2) and OCS.
The vibrational relaxation mechanism for the (nu)(,1) mode of neat liquid OCS under its own vapor pressure is investigated as a function of temperature through the isotropic Raman lineshape. The vibrational relaxation mechanism for the (nu)(,1) mode is attributed to dephasing and discussed qualitatively in terms of attractive dipolar forces.
The study of the (nu)(,1) mode vibrational relaxation in OCS is extended to include both temperature and pressure as variables. The results are found to support the conclusions drawn in the OCS vapor pressure study concerning the nature of the vibrational relaxation.
Issue Date:1984
Type:Text
Description:196 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1984.
URI:http://hdl.handle.net/2142/70274
Other Identifier(s):(UMI)AAI8502168
Date Available in IDEALS:2014-12-15
Date Deposited:1984


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