Interaction potentials of LiH, NaH, KH, RbH, and CsH

Observation of the shallow 2 Π 1 state of NaH

The 2 ¹Π state of NaH has been observed up to the last bound vibrational level using pulsed optical-optical double resonance fluorescence depletion spectroscopy. A total of 20 rovibrational energy levels ( v = 2-4 and J = 1-9) were assigned to this electronic state by means of comparing the successive rovibrational spectra to the eigenvalues of the ab initio potential energy curve. The decrease of background fluorescence near the atomic asymptotic limit Na(3d) + H(1s) is an indication of reaching the dissociation limit of the NaH 2 ¹Π state. Unobserved rovibrational levels ( v = 0 and 1) are due to poor Franck-Condon overlap of 2 ¹Π ← A ¹Σ⁺ transition within the accessible rovibrational levels of intermediate A ¹Σ⁺ state of this work.

Spectroscopic determination of the ground-state dissociation energy and isotopic shift of NaD

Stimulated emission pumping with fluorescence depletion spectroscopy is used to determine the NaD X ¹Σ⁺ ground-state dissociation energy and its isotopic shift. A total of 230 rovibrational levels in the range 9 ≤ v″ ≤ 29 and 1 ≤ J″ ≤ 11 are observed, where v″ = 29 is about 50 cm^-1 below the dissociation limit. Analysis of the highest five vibrational levels yields the dissociation energy D_e = 15 822 ± 5 cm^-1 with a vibrational quantum number at dissociation v_D = 31.2 ± 0.1. The energy difference in the well depth of this isotopologue with respect to that of NaH is δD_e = D_e(NaH) - D_e(NaD) = -7 cm^-1. A new set of Dunham coefficients is derived to fit all the observed energy levels to within the experimental uncertainty.

Cold interactions and chemical reactions of linear polyatomic anions with alkali-metal and alkaline-earth-metal atoms

Cold interactions and channels of chemical reactions between linear polyatomic anions and atoms are investigated, opening the way for sympathetic cooling and controlled chemistry in these systems.

Asymptotic exchange energy of heteronuclear dimers

A simple expression for the asymptotic exchange energy of heteronuclear dimers is derived from the surface integral method. A five-dimensional hypersurface, consisting of all spherical surfaces centered at the nucleus of the atom with higher ionization energy, more appropriate for the case where the two atoms have different ionization energies, is used in the surface integral. All integrals are carried out analytically. Compared with the exchange energy of Smirnov and Chibisov, which is also obtained from the surface integral method with a hypersurface consisting of all infinite planes perpendicular to the internuclear axis, the present result is much simpler. The exchange energies of alkali hydrides are computed as an illustration. It is shown that the present method and the method of Smirnov and Chibisov are complementary to each other.

Dissociation energy of the ground state of NaH

The dissociation energy of the ground state of NaH was determined by analyzing the observed near dissociation rovibrational levels. These levels were reached by stimulated emission pumping and fluorescence depletion spectroscopy. A total of 114 rovibrational levels in the ranges 9<or=v(")<or=21 and 1<or=J(")<or=14 were assigned to the X (1)Sigma(+) state of NaH. The highest vibrational level observed was only about 40 cm(-1) from the dissociation limit in the ground state. One quasibound state, above the dissociation limit and confined by the centrifugal barrier, was observed. Determining the vibrational quantum number at dissociation v(D) from the highest four vibrational levels yielded the dissociation energy D(e)=15 815+/-5 cm(-1). Based on new observations and available data, a set of Dunham coefficients and the rotationless Rydberg-Klein-Rees curve were constructed. The effective potential curve and the quasibound states were discussed.