15min:

AMANDA ROSS, Université Lyon 1 and CNRS (LASIM, UMR 5579), 69622 Villeurbanne, France; ADJO ADOHI-KROU, UFR SSMT Université de Cocody, 22 BP 582 Abidjan, Ivory Coast Republic; WLODZIMIERZ JASTRZEBSKI, Institute of Physics, Polish Academy of Sciences, Al. Lotnikóv 32/46, 02-668 Warsaw, Poland; PAWE\L KOWALCZYK, Institute of Experimental Physics, Warsaw University, ul. Hoza 69, 00-681 Warsaw, Poland; AND ANDREY V. STOLYAROV, Department of Chemistry, Moscow State University, 119992 Moscow, Russia.

Two-colour polarization labeling experiments measuring the D X system of NaK have furnished observations of the D ¹ state of NaK up to v" = 42. The last observed level is located 7 cm^-1 below the Na(3p ²P_3/2) + K(4s) atomic asymptote, clearly indicating the dissociation products of this state. The vibrational progressions all exhibit irregular intervals, predominantly because of strong interactions with the nearby d ³ state, which also dissociates to Na(3p) + K(4s) atoms. The polarization data have been combined with some resolved fluorescence D X transitions, and analyzed by fitting to spectroscopic parameters and to an analytical potential curve. A full deperturbation treatment has not been attempted, but a ``robust'' weighting scheme has been used to reduce the influence of levels that cannot be properly represented by a single channel model. Parameters determined in a fit to a potential curve include T_e = 20090.15 \pm 0.02 cm^-1, D_e = 2157.0 \pm 0.3 cm^-1, R_e = 4.155 \pm 0.002 Å, with an unweighted root mean square error of 0.12 cm^-1 for 959 data.