High-resolution laser spectroscopy of LiAr:: Improved interaction potential and spin-rotation-coupling in the ground state X 2Σ+

The spin-rotation coupling constant gamma has been determined to be -0.15(6).0(-3) cm(-1) for vibrational levels v=0, 1, and 2 of the X (2)Sigma (+) state of (LiAr)-Li-7 by means of an analysis of the high-resolution absorption spectrum due to the A <--X transition in the 670-677 nm region. All rovibrational levels of the X (2)Sigma (+) state have been observed, and improved values have been obtained for the spectroscopic parameters of vibration and rotation. In addition, the dispersed fluorescence A -->X has been recorded by populating selectively a particular rovibrational level of the A state. Using all experimental data, an improved X (2)Sigma (+) interaction potential has been determined for (LiAr)-Li-7, which is provided in the form of an analytical Hartree-Fock-Dispersion function. (C) 2001 American Institute of Physics.