title: Experimental study of the NaK 3 3Pi double minimum state.
abstract: We have used the Doppler-free, perturbation-facilitated optical-optical double-resonance technique to investigate the vibrational, rotational, and hyperfine structure of the 3 (3)Pi double minimum state of NaK. Since this electronic state arises from an avoided crossing with the nearby 4 (3)Pi state, we observe striking patterns in the data that provide a sensitive probe of the electronic wave function in the various regions of the double well potential. A single-mode cw dye laser excites 2(A) (1)Sigma(+)(v(A),J) approximately 1(b) (3)Pi(Omega=0)(v(b),J) mixed singlet-triplet "window" levels from thermally populated rovibrational ground state levels, 1(X) (1)Sigma(+)(v(X),J+/-1). Further excitation by a single-mode cw Ti:sapphire laser selects various 3 (3)Pi(0)(v(Pi),J(Pi)) rovibrational levels, which are detected by observing direct 3 (3)Pi(0)-->1(a) (3)Sigma(+) fluorescence in the green spectral region. Using the inverse perturbation approximation method, we have determined a 3 (3)Pi(0) potential curve that reproduces the measured energies to approximately 0.24 cm(-1). In addition, the hyperfine and spin-orbit constants, b(F) and A(v), have been determined for each region of the potential curve.
authors.affiliation: Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
authors.forename: L
authors.initials: L
authors.lastname: Morgus
authors.forename: P
authors.initials: P
authors.lastname: Burns
authors.forename: R D
authors.initials: RD
authors.lastname: Miles
authors.forename: A D
authors.initials: AD
authors.lastname: Wilkins
authors.forename: U
authors.initials: U
authors.lastname: Ogba
authors.forename: A P
authors.initials: AP
authors.lastname: Hickman
authors.forename: J
authors.initials: J
authors.lastname: Huennekens