The Effective Mass of Base Frame SiCl2 for Si-H Chromophores Stretching Vibrations in H2SiCl2

The spectra from 2000 to 9000 cm-1which include△v=1~4(△v=m+n; mandnare vibrational quanta of excitation in two bonds) band of SiH stretching vibration were recorded by a Bruker IFS 120HR Fourier transform spectrometer. The Fourier transform intracavity laser absorption spectroscopy (FT-LCLAS) was used to record the band of △v=6 SiH stretching vibration around 12345 cm-1. The Blackman-Harris-3-Termwas adopted the apodization function in FTIR. The resolution of all the obtained spectra is 0.2 cm-1. The Si-H symmetric and asymmetric stretching vibrational modes were assigned. Assuming the SiCl2 to be a base frame for the stretching vibration of two SiH chromophores, the treatment ignored all the vibrations in the H2SiCl2 molecule except the two SiH stretching vibrations. Adopting the anharmonically coupled anharmonic oscillator local mode model (ACAO) and using the programused to optimize the spectroscopic constants of the H2X-type molecule, the Morse dissociation energy De, the Morse oscillator parameters α and the couple coefficient of the potential energy function frr′were determined by fitting the observed vibrational band centers to Hamiltonians matrix. It showed that the H2SiCl2 molecule has stronger anharmoic character and weaker inter-bond coupling. The fitting results are in good agreement with the observed levels and the standard deviation of fitting is less than 1 cm-1. Therefore, the assumption of SiCl2 being a base frame for the two SiH chromophores is proved to be a good approximation. Substituting the mass of SiCl2 base frame as the 4th variable into the program, the obtained results indicate that the effective mass of SiCl2 base frame is 75.