Experimental study of the NaK 3Π3 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.

Spin–orbit coupling of the NaK 33Π and 31Π states: Determination of the coupling constant and observation of quantum interference effects

“…In the present work, we obtained the value A v T ¼32 ¼ ð3:179 AE 0:005Þ cm À1 , which is consistent with |H el | and with A v T values obtained for many different NaK 3 3 P vibrational levels that were reported in Ref. [15].…”

“…We use a single-mode cw dye laser (the ''pump'' laserCoherent model 699-29) to excite NaK molecules from a selected ro-vibrational level of the molecular ground state 1(X) 1 R + to the ''intermediate state'', which is a level of the 2(A) 1 R + electronic state or a level with mixed 1(b) 3 P X $ 2(A) 1 R + character [8,9,12,14,15]. The mixed levels 1(b) 3 …”

“…We carried out calculations based on the published molecular constants of the NaK 3 1 P state [11,66] and the reported levels of the NaK 3 3 P state (EPAPS Table 2 of Ref. 15) which indicate that the unperturbed 3 1 P 1 (v = 6,J = 19) and 3 3 P 0 (v = 32, J = 19) levels should indeed be nearly degenerate and lie at the appropriate energy necessary to identify them with the levels observed in the figure.…”

“…Heteronuclear alkali molecules have permanent dipole moments and are, therefore, of particular interest because, in principle, they can be oriented in an optical lattice [1][2][3][4][5][6][7]. In our laboratory at Lehigh University we have carried out a series of high-resolution spectroscopic studies of various excited electronic states of the heteronuclear alkali diatomic molecule NaK [8][9][10][11][12][13][14][15][16][17]. We have been particularly interested in the fine and hyperfine structure of these states and how variations in these structures with vibrational and rotational quantum numbers reflect changes in the electronic wavefunction with internuclear separation.…”

“…Using the experimental potentials of Refs. [15], [11], [76] and [77] with the theoretical transition dipole moments of Magnier et al, we calculate…”