Potential curve of NaKathinsp;3Sgr;+state near dissociation limit

摘要

Vibrational levels near the dissociation limit of NaKathinsp;thinsp;3Sgr;+state are observed with an opticalndash;optical double resonance technique. High resolution spectra are sensitively detected with the combination of perturbation facilitated polarization spectroscopy with frequency modulation spectroscopy. An electronically excited state, theBthinsp;1Pgr; state, is mixed with thecthinsp;3Sgr;+state through spinndash;orbit interaction. The transition from theXthinsp;1Sgr;+state to theathinsp;3Sgr;+state through theBthinsp;1Pgr; state is facilitated by the perturbation by thecthinsp;3Sgr;+state. Hyperfine structures of theathinsp;3Sgr;+(v=3minus;16,N=4minus;25) state are resolved with this spectroscopic technique and found to be independent of vibrational and rotational quantum number. Theathinsp;3Sgr;+state can only be perturbed by theXthinsp;1Sgr;+state through the hyperfine interaction. The vibrational levels (vle;16) of theathinsp;3Sgr;+state are demonstrably not perturbed by theXthinsp;1Sgr;+state. The potential curve of theathinsp;3Sgr;+state is determined by the nearhyphen;dissociation expansion fitting of molecular constants and the inverse perturbation analysis method. The coefficientsC6,C8, andC10of the potential function are determined to be (12.75plusmn;0.15)times;106cmminus;1Aring;6, (2.22plusmn;0.19)times;108cmminus;1Aring;8, and (1.100plusmn;0.061)times;1010cmminus;1Aring;10, respectively. The dissociation energy,De, is obtained to be 207.858 plusmn; 0.019 cmminus;1, which is 2.8 cmminus;1above the highest observed vibrational level (v=16).