Yide Gao

Investigation of collisional quenching of CCl2 (Ã 1B1 and ã 3B1) by alkanes

CCl2 free radicals were produced by a pulsed dc discharge of CCl4 (in Ar). Ground electronic state CCl2(X) radical was electronically excited to A 1B1(0,4,0) vibronic state by Nd:YAG laser pumped dye laser at 541.52 nm. The laser induced fluorescence signal is observed to be a monoexponential decay curve corresponding to the decay of the A state under supersonic jet conditions and the lifetime of CCl2(A→X) transition was measured being 0.83±0.03 μs. Experimental quenching data of excited CCl2(A 1B1 and a 3B1) by alkanes were obtained by observing the time-resolved total fluorescence signal of the excited CCl2 radical in a cell, which showed a superposition of two exponential components under the presence of a quencher. The quenching rate constants of A(1B1) and a(3B1) states of CCl2, KA, and Ka, were derived by analyzing the experimental data according to a proposed three-level model to deal with the CCl2(X 1A1,A 1B1,a 3B1) system. KA and Ka increase steadily by increasing the number of C–H bonds conta...

Collisional quenching of CCl2 radicals in the A1B1 (0,4,0) and a3B1 states by alcohols

Abstract The experimental quenching data for CCl 2 in the excited state, A 1 B 1 (0,4,0) , by alcohols were obtained through observing its time-resolved total fluorescence signal, which showed a superposition of two exponential decay components. The quenching rate constants K A for CCl 2 (A) state and K a for CCl 2 (a) state were derived by analyzing the experimental data according to a proposed three-level-model to deal with CCl 2 ( X 1 A 1 , A 1 B 1 , a 3 B 1 ) system. K A and K a increase on the whole with increasing the number of C–H bonds in alcohol molecules.

The fluorescence excitation spectra of the A 1Au(S1)–X 1Ag(S0) transition of biacetyl: Determination of the band origin

Laser-induced fluorescence spectra of the A 1Au(S1)–X 1Ag(S0) transition of biacetyl are observed under supersonic jet condition. Three weaker bands have been observed at 154, 67, and 58 cm−1 to the red of the previously presumed band origin 000 (at 22 336 cm−1). The observed tunneling splitting 1.05 cm−1 for the G01 band and 1.68 cm−1 for the A01 band are compared to the theoretical result. Based on the tunneling splitting, the true band origin 000 is determined for the first time as the furthest weaker band at 22 182 cm−1. The three weaker bands have been assigned as 000, G01, and A01 transitions, respectively.

Investigation of collisional quenching of CCl2( 1B1 and ã 3B1) by some inorganic molecules

CCl2 free radicals were produced by a pulsed dc discharge of CCl4 in Ar. The radicals were electronically excited from the ground electronic state to the A 1B1 (0,4,0) state with Nd:YAG laser pumped dye laser at 541.52 nm in the rR subband. Experimental quenching data of CCl2(A 1B1) and CCl2(a 3B1) by O2, N2, NO, NH3, H2O, CO2, CS2, SO2, and SF6 molecules were monitored by observing the time-resolved total fluorescence signals of the excited CCl2 in a cell where the total pressure was 200 Pa. The observed profiles showed a superposition of two exponential decay components in the presence of the quencher. The quenching rate constants kA of CCl2(A) and ka of CCl2(a) were derived by analyzing the experimental data according to a proposed three-level-model to deal with the CCl2( 1A1, A 1B1, a 3B1) system. The order of magnitude for the rate constant of the quenching of the A state (kA) is 10−10 cm3 s−1, while for the quenching rate constant of the a state (ka) is 30–50% of kA. By changing the excitation wavelength, the radicals of the ground electronic state CCl2() were electronically excited to a different vibronic state, i.e. (0,3,0), (0,4,0), (1,3,0), (0,6,0), (1,4,0) and (2,2,0), of CCl2(A 1B1). We studied the kinetics of the collisional quenching by H2O and NH3 molecules of CCl2(A 1B1) in different vibronic states. It is found that the total quenching rate constant kA is little dependent on the vibronic state. It is possible that the reaction between the quencher molecule and CCl2(A 1B1) undergoes a process without a barrier. An explanation for the measured quenching data using the complex model based on attractive forces between the collision partners is presented.