Author

Peng Wang

Date of Award

1996

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Abstract

This thesis describes a newly built vacuum ultraviolet (VUV) laser/time-of-flight (TOF) mass spectrometer system in great detail. The theoretical background behind the techniques is also provided. Tunable, coherent, and monochromatic VUV "laser" radiation was generated by the nonlinear optical technique of two-photon resonantly enhanced four-wave difference-mixing (FWDM) in Kr gas. The Frequency resolution of the recorded spectra is estimated to be {dollar}\leq{dollar}0.2 cm{dollar}\sp{lcub}-1{rcub}.{dollar} The mass resolution, m/{dollar}\Delta{dollar}m, of the linear TOF mass spectrometer {dollar}\geq{dollar}500, which was sufficient to obtain single isotopomer data.;With this instrument, vibrationally and rotationally resolved spectra of the {dollar}E0\sp+{dollar} (v{dollar}\sp\prime=173-203){dollar} ion-pair state {dollar}\leftarrow X0\sp+{dollar} (v{dollar}\sp{lcub}\prime\prime{rcub}=0){dollar} ground state transition of jet-cooled BrCl near 145 nm was recorded and analyzed for the first time. J-numbering for all the rotationally resolved isotopomer bands were determined from ground state combination differences, and molecular constants were derived. The relative vibrational numbering of the isotopic features for BrCl was established by fitting the band origins and band heads to an appropriate mass-reduced Dunham expansion. The absolute vibrational numbering chosen was that which yielded a minimum standard deviation.;Mass-resolved spectra of the {dollar}\rm2\sp1\Sigma\sbsp{lcub}u{rcub}{lcub}+{rcub}(v\sp\prime=1-3)\leftarrow X\sp1\Sigma\sbsp{lcub}g{rcub}{lcub}+{rcub}(v\sp{lcub}\prime\prime{rcub}=0){dollar} transition of jet-cooled Cl{dollar}\sb2{dollar} between 78000 and 80100 cm{dollar}\sp{lcub}-1{rcub}{dollar} were also recorded and rotationally analyzed. Unambiguous isotopomer assignments for the numerous features associated with each vibrational band in this spectral region were made for the first time. Although the system appears to be perturbed, measured vibrational isotope shifts strongly support a change of +1 in the accepted 2-state v{dollar}\sp\prime{dollar} numbering.

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.