Molecular Beam Electric Deflection and Resonance Spectroscopy of the Heteronuclear Alkali Dimers: 39K7Li, Rb7Li, 39K23Na, Rb23Na, and 133Cs23Na

Abstract

Molecular beam electric resonance spectra for several heteronuclear alkali dimers have been obtained for the ${\mathrm{|M}}_J\text{|=0→ 1}$ transition in the J = 1, v=0 state in a supersonic beam. Values of the ground vibronic Stark coefficient ${\mu }_0^2{\mathrm{/B}}_0$ and the nuclear quadrupole coupling constants eqQ were obtained. The values of ${\mu }_0^2{\mathrm{/B}}_0$ were ${\text{(2.269± 0.002)× 10}}^{\text{−19}}\hspace{0.17em}{\mathrm{cm}}^3$ for ³⁹K⁷Li, ${\text{(3.697± 0.004)× 10}}^{\text{−19}}\hspace{0.17em}{\mathrm{cm}}^3$ for ⁸⁵Rb⁷Li, and ${\text{(3.966± 0.004)× 10}}^{\text{−18}}\hspace{0.17em}{\mathrm{cm}}^3$ for ³⁹K²³Na. Badger's rule was used to estimate B₀ and to determine the following values for the molecular electric dipole moment: ${\mu }_0{(}^{39}{\mathrm{K}}^7\mathrm{Li}\text{)=3.45± 0.1\hspace{0.17em}}\mathrm{D}{\mathrm{,\; \mu }}_0{(}^{85}{\mathrm{Rb}}^7\mathrm{Li}\text{)=4.00± 0.1\hspace{0.17em}}\mathrm{D}$ , and ${\mu }_0{(}^{39}{\mathrm{K}}^{23}\mathrm{Na}\text{)=2.76± 0.1\hspace{0.17em}}\mathrm{D}$ , where the errors arise from the uncertainties in the rotational constant. Electric deflection was used to obtain a value of μ²/B for Rb²³Na of ${\text{(6.6± 0.5) × 10}}^{\text{−19}}\hspace{0.17em}{\mathrm{cm}}^3$ and hence $\text{3.1± 0.3\hspace{0.17em}}\mathrm{D}$ for the dipole moment, while rf spectroscopy with power broadening was employed with ¹³³Cs²³Na to obtain ${\text{(1.81± 0.02) × 10}}^{\text{−18}}\hspace{0.17em}{\mathrm{cm}}^3$ for ${\mu }_0^2{\mathrm{/B}}_0$ and hence $\text{4.75± 0.2\hspace{0.17em}}\mathrm{D}$ for μ0. The translational and rotational temperatures in the supersonic beams were estimated from velocity scans and quadrupole voltage scans. An ionic model is used in a heuristic interpretation of the dipole moment results.