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RESEARCH PRODUCT

Analysis of the Infrared Fourier Transform Spectrum of the Spectra of Silane in the Range 2930-3300 cm(-1).

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The infrared spectrum of (28)SiH(4) between 2930 and 3300 cm(-1) was recorded using the Laboratoire de Physique Moleculaire et Applications (LPMA.) Fourier transform spectrometer. The instrumental response function width chosen makes it possible to obtain a Doppler-limited spectrum. The observed spectrum belongs to the tetrad built with one quantum of stretching mode (nu(1) or nu(3)) and one quantum of bending mode (nu(2) or nu(4)). The excited states are formed from eight vibrational sublevels: nu(1) + nu(2)(E), nu(1) + nu(4)(F(2)), nu(2) + nu(3)(F(1) + F(2)), and nu(3) + nu(4)(A(1) + E + F(1) + F(2)). The intricacy of the upper states was resolved using the variations of the line strength between the 297 K and 209 K spectra and the precise knowledge of the ground state. For analysis with the vibrational extrapolation method, we used the previous results for the fundamental bending dyad (nu(2)/nu(4)) and the stretching dyad (nu(1)/nu(3)). The Hamiltonian is expanded through the sixth order of approximation for the ground and the bending states, the fifth order for the stretching states, and the fourth order for the tetrad states in the Amat-Nielsen classification. About 1033 pieces of data are used in the analysis and the weighted standard deviation obtained is 4.6 x 10(-3) cm(-1). Copyright 1999 Academic Press.