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在B3LYP/6-31+G(d,p)理论水平下采用基于波恩-奥本海默近似的从头算分子动力学方法重新研究了O-与CH3F,反应经抽氢生成OH-和生成H2O的两条产物通道.反应轨线从反应初始过渡态开始,采用300 K时的热取样确定初始条件,同时为对比不同的初始碰撞平动能条件下产物通道的变化,分别限定过渡矢量上的能量为2.1、36.8及62.8 kJ·mol-1进行轨线计算,所有轨线计算的结果表明抽氧生...

Two kinds of spectrum, the Raman-Induced Kerr Effect Spectrum(RIKES)and the Photoacoustic Raman Spectrum(PARS),were measured simultaneously for the ν1 vibrational band of methane. The difference between the profiles of the two spectra obtained with linearly polarized pump and Stokes laser beams lies in that, the intensity of RIKES spectrum is stronger at the small Raman shift side, and is weaker at the large Raman shift side compared to the PARS spectrum. It was confirmed that this difference is caused by the interference between the resonant and non-resonant parts of the third order non-linear susceptibility.

At the magic angle, the time_of_flight mass_spectrometer (TOF-MS) profile depends only on the translational energy distribution of photofragment, and is indep endent of the angle distribution of recoil momentum, therefore, the translationa l energy distribution is usually determined by fitting the measured TOF-MS profi le. Different from the above procedure, we take another approach in the present work. According to this method, by measuring three widths at half maximum (t 1/2), one-fourth maximum (t1/4) and three-fourth m aximum (t 3/4) of the TOF-MS profile, the averaged translational energy, th e width of translational energy distribution, as well as the width of instrumental func tion can be determined from numeric tables or mathematical expressions. In this method, both the translational energy distribution and the instrumental function are described by Gaussian functions.

The spectra of N 2 O + ions in A 2 Σ + state have been investigated. Pure parent N 2 O + ions, in the X 2 Π 3/2,1/2 (000) state, were prepared by (3+1) multiphoton ionization of jet-cooled N 2 O molecules using a laser beam at 360.55 nm. By introducing another laser, the parent ions were excited to the predissociative A 2 Σ + state, and the fragment NO + was detected by a time-of-flight mass spectrometer. The NO + photofragment excitation (PHOFEX) spectra were recorded by scanning the dissociation laser in the wavelength range of 278—328 nm. The PHOFEX spectra could be attributed completely to the A 2 Σ + ←X 2 Π transition of N 2 O + , in which most vibronic bands were observed for the first time. By considering the Fermi resonance between the ν 1 and ν 2 modes, the spectra were assigned, and the spectral constants, such as vibrational frequencies, anharmonic constants, and Fermi interaction constant, were obtained with relatively high reliability and precision.

About 50 spectral lines due to the (2+1) resonance-enhanced multiphoton ionization (REMPI) of atomic sulfur, generated in the sequential multiphoton dissociation of SO2 at probing wavelengths, in the 243—263 nm region has been observed. Besides most of the lines which are due to the two-photon transition from the ground states 3P2,1,0 to the Rydberg states 3P, 3D, 3F until n=10 of S atom, several new lines including the spin forbbiden transition 1P0, 5S0←3P and the two-photon transitions from the excited state 1D2 to the Rydberg states np1,3D, 1,3F are observed. Intensities of some lines have been calculated and compared with the experimental results.

The influence of the different gas ratios (SO2/Ar) on the vibronically resolved laser-induced fluorescence excitation spectra of the SO2( 1A2— 1A1) system was investigated under the supersonic jet conditions.High resolution spectra of two complete progressions (1,m,1),(0,n,1) were obtained,in which the rotational structures of the (0,9,1),(0,10,1),(1,7,1),(1,5,1)-(0,0,0) bands were observed,for the first time,so long as we know.The assignments of 847 rotationally resolved lines were based on an asymmetric top simulation,which results in the determination of the rotational and centrifugal distortion constants of each vibrational level of state.The approximate geometry parameters of state was derived to be r(S—O)=0.160nm,∠OSO=101.64°.In addition,a discussion on the inertial defect of each vibrational level of state was presented.