Effect of inter-molecular collision on isotope separation by infrared multiphoton dissociation

我们建立了一套拉曼光谱测量装置，测量了C_5H_8O在CO_2激光辐照下的含时拉曼光谱。由拉曼谱估算的C_5H_8O的平均振动能与用速率方程模型模拟的C_5H_8O的平均振动能一致，该模型包括光吸收、诱导发射、碰撞引起的振动激发和去激发以及单分子解离过程。这表明了模拟的有效性。我们还阐明了同位素分离因子随气压增加而增加的机理。

We constructed an apparatus for Raman spectrum measurement and measured time-dependent Raman spectra of C_5H_8O irradiated by a CO_2 laser. The average vibrational energy of C_5H_8O estimated from the Raman spectra agrees with one simulated by using a rate-equation model including processes of photo-absorption, induced emission, vibrational excitation and de-excitation induced by a collision, and uni-molecular dissociation. This indicates the validity of the simulation. We also elucidated the mechanism for the increase of isotopic separation factor with increasing gas pressure by using this simulation technique.