Spectroscopic study of the acetylene species

This thesis describes recent spectroscopic studies of acetylene and its HCCD isotopomer. Three different kinds of experiments have been performed: Laser-Induced Fluorescence (LIF), Dispersed Fluorescence (DF), and Stimulated Emission Pumping (SEP). Each experiment has yielded new discoveries in the vibrational and rotational dynamics of acetylene in its ground electronic state (X) state and its first excited singlet state (A) state. The goal of my research at MIT has focused on making contributions to the investigation of isomerization processes in acetylene. These include the linear vinylidene isomerization process on the X state and the trans -+ cis isomerization process on the A state. I have reasons to believe that the local bending motion is the major contributor in both processes. LIF spectroscopic study of the A state of acetylene has led to new assignments of 23' and 13' bands which involve a symmetry. The frequency of the upper state symmetric CH stretch mode normal, v, is determined to be 2880.5 cm-1, 60 cm-llower than the presently-accepted value of 3040.6 cm-1[104, 106]. DF spectroscopic study of the X state of acetylene has revealed a collisional K-changing process in the A state. In order to model theoretically the intensities measured from the present DF dataset, an local mode based Franck-Condon calculation scheme is given, and the results are shown to agree with the nodal structures exhibited in the experimental observations to within two quanta in both the CC stretch and the trans-bending coordinates. Improvements on the FC calculation are expected to aid in the direct assignment of the HCCD DF spectra, which are more complicated than those from the symmetric isotopomer, HCCH, due to reduced symmetry.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Chemistry.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2003

Author dc:creator

• Duan, Zicheng, 1976-

Advisor dc:contributor.advisor

• Robert W. Field.

• Chemistry.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/29320

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/29320