【摘要】 <正> 碘甲烷分子与激光相互作用,发生的光解、激发电离等化学或物理过程已由许多人进行过研究.本文报导用多光子电离飞行质谱和光电子能谱技术研究碘甲烷通过(?)态和(?)态的多光子过程的主要实验结果和结论.实验用Nd:YAG 激光器泵浦染料激光器,可调谐的染料(R590)激光经倍频或与YAG 基频1.06μm 混频后分别得到280nm 或366nm 附近的紫外光,能量为0.2—2mJ/脉冲,时间脉更多还原

【Abstract】 The collision-free multiphoton ionization of jet cooling CH₃I was studied using apulsed laser,tunable around 280 and 366nm with TOF mass spectrometer and mag-netic-bottle TOF photoelectron spectrometer.MPI of CH₃I in 280nm region via valence （?） state can be explained by ladder-switch mechanism according to the following experimental results.The parent ions arealmost abscent in the MPI TOF MS.I⁺ MPI spectrum gives three resonances corre-sponding to two-photon excitation of I atom at 279.72,279.25 and 278.50 nm.The Iionic state due to 2+1 REMPI of I atom can be assigned from the REMPI PES.In 371—365nm I⁺,CH₃⁺ and CH₃I⁺ were observed in MPI MS.The mass-selectedMPI spectra of CH₃I⁺ and daughter ion I⁺ have similar profiles.In the spectra thetwo peaks at 365.90 and 369.92nm are assigned to be two-photon resonance with theRydberg （?） state Π（0,0）and Σ（0,0） of CH₃I respectively.The formation of theCH₃I^{+ 2}Π_3/2 and ²Π_1/2 state created by 2+1 and 2+2 REMPI resectively were foundin PES.REMPI of CH₃I around 366nm is consistent with the ladder mechanism inwhich CH₃I is excited into （?） state upon a two photon absorption and parent ion isformed by the overall 2+1 of 2+2 MPI process.The fragment ions are produced byfurther dissociation of CH₃I⁺ at （?） state.更多还原