6533b830fe1ef96bd129790a

RESEARCH PRODUCT

Permanent electric dipoles andΛ-doubling constants in the lowestΠ1states of RbCs

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The article presents first experimental data on the Stark induced $e\text{\ensuremath{-}}f$ mixing in the $(4)\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Pi}$ state of the $^{85}\mathrm{Rb}^{133}\mathrm{Cs}$ molecule, as well as the ab initio calculations of permanent electric dipole moments $(d)$ in the $(1,2,3,4)\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Pi}$ states and $q$ factors in the $(2,4)\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Pi}$ states. The appearance of the ``forbidden'' lines in the laser-induced $(4)\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Pi}\ensuremath{\rightarrow}X\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Pi}^{+}$ fluorescence spectrum in the presence of an electric field allowed us to obtain, for the rovibronic ${v}^{\ensuremath{'}}({J}^{\ensuremath{'}})=2(82)$ level of the $(4)\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Pi}$ state correlating to the $\mathrm{Rb}(4d)+\mathrm{Cs}(6s)$ atomic limit, the ratio $q∕d=0.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}∕\mathrm{D}$ with 20% experimental error. Electronic structure calculations on the ground and excited states of the RbCs molecule were performed in the framework of the Hund's $a$-coupling scheme by means of the many-body multipartitioning perturbation theory. The ab initio $d(R)$ estimates revealed large values of about $d\ensuremath{\approx}\ensuremath{-}7\phantom{\rule{0.3em}{0ex}}\mathrm{D}$ for the $(4)\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Pi}$ state. The calculated $q$ factor value for the $(2)\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Pi}$ state is in excellent agreement with the literature data. The theoretical estimate of the $q∕d$ ratio for the ${v}^{\ensuremath{'}}({J}^{\ensuremath{'}})=2(82)$ level of the $(4)\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Pi}$ state agrees satisfactory well with the present experimental value.