High-resolution laser spectroscopy of LiAr: Improved interaction potentialand spin-rotation-coupling in the ground state X (2)Sigma(+)

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 (+) s tate of (LiAr)-Li-7 by means of an analysis of the high-resolution absorpti on spectrum due to the A <--X transition in the 670-677 nm region. All rovi brational levels of the X (2)Sigma (+) state have been observed, and improv ed values have been obtained for the spectroscopic parameters of vibration and rotation. In addition, the dispersed fluorescence A -->X has been recor ded by populating selectively a particular rovibrational level of the A sta te. Using all experimental data, an improved X (2)Sigma (+) interaction pot ential has been determined for (LiAr)-Li-7, which is provided in the form o f an analytical Hartree-Fock-Dispersion function. (C) 2001 American Institu te of Physics.