15min:

JIA-JEN DU, CHIA-HSIN CHEN AND BOR-CHEN CHANG, Department of Chemistry, National Central University, 300 Jhongda Road, Jhongli 32001, Taiwan.

Unknown bands that were not seen in the nascent emission spectra following the near-UV photolysis of bromomathanes (CHBr_3-nCl_n, n= 0, 1, 2 and CH₂Br₂) were observed in the 520-820 nm region of the nascent emission spectra following the 266 nm photolysis of iodomethanes (CHI₃, CH₂I₂, and CH₃I) in a slow flow system at ambient temperature. We have dramatically improved the signal-to-noise (S/N) ratios of these unknown bands for further data analyses. Pressure dependence and temporal waveforms of the unknown bands were also recorded. The analyses show that these bands have the vibrational intervals of roughly 400 cm^-1 and possibly originate from the same upper level with emission to different lower levels. Moreover, the nascent emission spectra of photolyzing the deuterated or ¹³C-substituted isotopomers (CD₂I₂, CD₃I, and ¹³CH₂I₂) were also acquired, and the results indicate that the carrier molecule probably does not contain any hydrogen or carbon atoms. Our current progress will be presented.