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ROVIBRATIONAL SPECTROSCOPY IN HELIUM DROPLETS
by
Dmitry S. Skvortsov
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(CHEMISTRY)
August 2008
Copyright 2008 Dmitry S. Skvortsov
Object Description
| Title | Rovibrational spectroscopy in helium droplets |
| Author | Skvortsov, Dmitry S. |
| Author email | skvortso@usc.edu |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Chemistry |
| School | College of Letters, Arts and Sciences |
| Date defended/completed | 2008-06-12 |
| Date submitted | 2008 |
| Restricted until | Unrestricted |
| Date published | 2008-07-24 |
| Advisor (committee chair) | Vilesov, Andrey |
| Advisor (committee member) |
Kresin, Vitaly Reisler, Hanna |
| Abstract | This thesis covers different aspects of the spectroscopy of molecules andmolecular clusters embedded in helium droplets. The interaction between the trappedmolecules and the host He clusters as well as the use of helium as a media for novelmatrix isolation spectroscopy experiments will be discussed.; The rovibrational spectroscopy of spherical top molecules in helium droplets shows the matrix effect on the free rotation. The effect of the both intrinsic moment of inertia as well as increase of the anisotropy of the helium-molecule interaction potential is discussed.; Large enhancement of the intramolecular coupling in silane molecules trapped inside He cluster was observed. The deperturbation analysis shows increase of the interaction coefficient between ν1 and ν3 vibrational modes by a factor of 100 in liquid helium as compared to the gas phase.; Study of HCl clusters in helium droplets shows the formation of the cyclic structures up to the hexamers. These results indicate a non-planar twisted structure for tetramers, an envelope-like structure for pentamers and a pseudo bi-pyramid for hexamers. The absence of the bands due to free H-Cl stretches in the spectrum of large (HCl)n clusters (n > 20) is consistent with either branched structures with the surface.; Observation of the "broken symmetry" band in HCl dimer (H^35Cl - H^37Cl) allows the interchange-tunneling (IT) splitting of deltaν = 2.7 ± 0.2 cm-1 in the ν2 vibrationally excited state to be obtained, from which the matrix element of beta = 0.85 ± 0.15 cm^-1 was estimated. This coupling value is about a factor of two smaller than in the free dimers.; 2-chloroethanol molecules at temperature in the range of 300 – 600 K have been captured by helium droplets and studied via infrared spectroscopy in the range of O-H and C-H stretching bands. We found that the intensity ratio of the bands due to trans- and gauche- conformers follows the Arrhenius dependence, giving the enthalpy of interconversion, deltaH0= 1.12 ± 0.09 kcal/mol.; The effect of isotopic substitution on molecular rotations of CO2 have been studied via infrared spectroscopy in helium droplets. In the spectral region of 2ν2 + ν3 (3500 - 3700 cm^-1), rovibrational spectra of ^16OC^16O, ^16OC^18O, and ^18OC^18O have been obtained showing significant participation of surrounding helium in rotations. Enhancement of coupling of molecular rotations with helium has been observed for the asymmetric CO2 and attributed to increasing number of the interacting levels for ^16OC^18O molecules as compared to symmetric CO2 isotopic species, where odd rotational levels are missing. |
| Keyword | helium droplets; laser spectroscopy |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Type | texts |
| Legacy record ID | usctheses-m1402 |
| Rights | Skvortsov, Dmitry S. |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | http://www.usc.edu/isd/libraries/services/ask_a_librarian/email/ |
| Filename | etd-Skvortsov-20080724 |
| Archival file | uscthesesreloadpub_Volume26/etd-Skvortsov-20080724.pdf |
Description
| Title | Page 1 |
| Full text | ROVIBRATIONAL SPECTROSCOPY IN HELIUM DROPLETS by Dmitry S. Skvortsov A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (CHEMISTRY) August 2008 Copyright 2008 Dmitry S. Skvortsov |
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