HIGH-RESOLUTION LASER SPECTROSCOPY OF THE X(1)SIGMA(-NA-23-RB-85 MOLECULE() AND (1)(3)SIGMA(+) STATES OF (NARB))

High-resolution spectra of the B-1 Pi-->X(1) Sigma(+) transition of (N aRb)-Na-23-Rb-85 molecule are measured by the technique of the Doppler -free optical-optical double resonance polarization spectroscopy (OODR PS). The molecular constants of the X(1) Sigma(+)(v''=5-30) levels are determined, and the potential energy curve is constructed up to v''=3 0 by the RKR method. The time-resolved fluorescence intensity followin g the excitation to the B-1 Pi(v'=5,J'=around 20) level is measured, a nd the lifetime of the B-1 Pi(v'=5) level in collisionless limit is de termined to be 17.8 ns. The absolute value of the electric dipole mome nt of the B-1 Pi-X(1) Sigma(+) transition is determined to be 7.0 D in the region of 3.73 Angstrom<R<4.98 Angstrom. Transition lines to the (1)(3) Sigma(+) state from the B-1 Pi(v'=8,J'=15) level, which is pert urbed by the (1)3 Pi(1)(v(0),N=J=15) level, are measured by the Dopple r-free OODRPS. The energy spacing between the F-1 and F-3 components o f the (1)(3) Sigma(+)(v=4,N=15) level is observed to be smaller than 0 .001 cm(-1). The hyperfine splittings, which are described by Hund's c ase (b(beta s)), are observed, and the hyperfine constants A(Na) and A (Rb) of the (1)(3) Sigma(+)(v=4) level are determined to be 0.0293 and 0.0336 cm(-1), respectively. The hyperfine splittings are identified as originating from the Fermi contact interaction. From the analysis, it is concluded that the electron spins in the (1)(3) Sigma(+) state a re almost equally populated to the 5s(Rb) and 3s(Na) orbitals. (C) 199 6 American Institute of Physics.