The CO2 laser Stark spectroscopy was applied to the ν4 (SiF3 degenerate stretch) fundamental band of SiDF3. It was found that electric field-dependent interactions of the (Δl, ΔK) = (2, -1) type, caused by the vibrationally induced dipole moment, give remarkable perturbations in the ν4 vibrational state. Several perturbation-induced rovibrational transitions obeying the Δ(K - l) = ± 3 selection rules were observed in the Stark spectrum, and the C0 rotational constant, which is otherwise hard to obtain for a symmetric-top molecule, was determined to be 4133.55(19) MHz. The vibrationally induced dipole moment μr and the ordinary (2, -1) interaction constant r4 derived from the analysis are ±0.03516(13) D and ±1.896(52) MHz, respectively, the ± signs indicating that μr and r4 have the same sign. The band origin, the Coriolis constant Cζ4, and the vibration-rotation constant α4C are 994.302604(16) cm-1, 2210.26(20) MHz, and 10.070(25) MHz, respectively. The dipole moment is 1.35719(17) D in the ground state, and increases by 0.02649(10) D on excitation of the ν4 vibration. The uncertainties given in the parentheses correspond to three standard deviations. A theoretical treatment is presented on the relation between the vibrationally induced dipole moment μr and the vibrational change δμ4 of the dipole moment.
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics
- Physical and Theoretical Chemistry