Peng Wang

Date of Award


Degree Type


Degree Name

Doctor of Philosophy


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.



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