超声射流冷却丁二酮的激光诱导荧光激发谱

Supersonic Jet-cooled Laser-induced Fluorescence(LIF) Spectrum of Biacetyl

在超声射流条件下获得了丁二酮在 4 32 4 51nm波段的激光诱导荧光激发谱 .在前人标识为 0 00 带谱峰的红端观察到 3个很弱的谱峰分别位于 0 ,87,97cm- 1 处 (以 2 2 182cm- 1 为 0cm- 1 ) .在 87和 97cm- 1 附近精细扫描 ,观测到 87和 97cm- 1 谱峰的隧道分裂分别为 1.0 5cm- 1 和 1.68cm- 1 ,与理论计算的分裂值符合得很好 ,从而确定了S1 ←S0 跃迁 0 00 带的位置在 2 2 182cm- 1 .87cm- 1 和 97cm- 1 处的谱峰分别为丁二酮基态S0 到激发态S1 的卡齿模 (G1 0 )和反卡齿模 (A1 0 )振动激发 .此外 ,首次对丁二酮S1 —S0 态激光诱导荧光激发谱进行较完整的标识 ,得出S1 态的羰基骨架扭曲振动模的振动频率 91.1cm- 1 ,非谐性常数 4 .875cm- 1 .

The laser-induced fluorescence(LIF) excitation spectra of biacetyl in the range of 432—451 nm were obtained under the supersonic jet condition. Three weaker peaks, which are at 0, 87 and 98 cm^-1, respectively(related to 22 182 cm^-1) were observed in a high sensitivity spectrum at red-hand of 22 336 cm^-1 peak which was assigned as band origin previously. The tunnel splits for 87 and 97 cm^-1 peaks were observed in the hyperfine spectra. They are 1.04 cm^-1 and 1.68 cm^-1 for 87 cm^-1 peak and 97 cm^-1 peak respectively. These values are in agreement with calculated values very well. The band origin of S_1←S_0 transition is now determined at 22 182 cm^-1. A complete assignment of biacetyl LIF spectrum is done for the first time. The frequency of torsion mode is determined to be 91.1 cm^-1 , and the enharmonic constant is 4.875 cm^-1.