15min:

I. RUSSIER, M. AUBERT-FRECON, A. J. ROSS, F. MARTIN, A. YIANNOPOULOU AND P. CROZET, Laboratoire de Spectrométrie Ionique et Moléculaire (CNRS UMR5579), and Université Lyon I, Campus la Doua, Bâtiment 205, 69622 Villeurbanne Cedex, France.

Vibrational levels up to v=107 of the (1)¹_g state of ³⁹K₂, which dissociates to K(4s)²S+K(4p)²P_3/2, have been observed in high resolution Fourier transform records of C¹_u -> (1)¹_g fluorescence of potassium molecules in a heatpipe source. From a revised analysis of this system, we have constructed a rotationless RKR potential curve which extends to R=40.3 Å covering 99.2% of the (1)¹_g state. Vibrational and rotational constants (at J=0) have been calculated from this curve. The parameters describing the coulombic interactions between K(4s)+K(4p) atoms are given in a Hund's case (c) basis. From this work, the dissociation energy D_e for the (1)¹_g state is found to be 1290.30\pm0.09 cm^-1 (leading to a new value of T_e=16203.25 \pm0.09 cm^-1 for this state) and the long-range parameters are M²=25.30\pm0.02 e²a_o², R₀₁=7261\pm223 e²a_o⁵. These values are in good agreement with values obtained from the pure long range 0_g^- state analyzed by H. Wang, P. L. Gould and W. C. Stwalley (J. Chem. Phys. 106, 7899 (1997)).