High resolution laser spectroscopy of NaAr: Improved interaction potential for the ground state

The absorption spectrum of NaAr has been investigated with high resolution using a supersonic beam of molecules and a tunable dye laser. About 3 300 absorption lines due to the transition A ² Π ← X and B ² Σ ← X have been observed. In addition, we observed the spectral distribution of the fluorescence for a particular absorption line. From all experimental data the X ² Σ ⁺ interaction potential has been deduced in a fully quantum-mechanical method of approach. The potential is given in terms of an analytical Hartree-Fock-Dispersion function. For the equilibrium parameters of the X state we get R _e = 5.01(1) ? and D _e = 41.6(2) cm ^-1 . Received 28 August 2002 / Received in final form 15 October 2002 Published online 17 December 2002 RID="a" ID="a"Now at Knick Elektronische Messger?te, Beuckestr. 22, 14163 Berlin, Germany. RID="b" ID="b"e-mail: dz@kalium.physik.tu-berlin.de