| Résumé | SiP molecules have been produced in a molecular free jet apparatus by laser vaporizing a silicon rod in the presence of He doped with phosphine (PH3) gas. Excitation spectra have been observed in the 21200–22350 cm–1 range by monitoring laser induced fluorescence. Dispersed fluorescence spectra have been recorded out of the upper states of the excitation bands. The ground electronic state is X 2Πi with the spin–orbit splitting A=−186.774(11) cm−1, the harmonic wavenumber ωe=615.7(6) cm−1, and the equilibrium internuclear distance re=2.0775(17) Å. Two excited electronic states, A 2Σ+ and B 2Σ+, are observed at T0=427.4(5) and 21317.1(1) cm−1, respectively. The harmonic wavenumbers, ωe, and the equilibrium internuclear distances, re, are 680(2) cm−1 and 1.9658(13) Å, respectively, for the A 2Σ+ state and 455(1) cm−1 and 2.1278(8) Å, respectively, for the B 2Σ+ state. For the X 2Πi, A 2Σ+, and B 2Σ+ electronic states, RKR potentials have been generated. Franck–Condon factors for the B–X, B–A, and A–X systems have been calculated. A 2Σ+, v∼X 2Π1/2, v+1 perturbations have been observed. A deperturbation procedure has yielded the off-diagonal spin–orbit electronic matrix element equal to 51(8) cm−1. This work represents the first spectroscopic investigation of the SiP molecule. |
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