The finehyphen;structure analyses of highly resolved lowhyphen;temperature absorption spectra of four different isotopes of the NO molecule in the vacuum ultraviolet by Miescher and cohyphen;workers have revealed a wealth of detailed information, among other results, on the2Pgr; states of thenppgr; Rydberg series leading to the first ionization limit and on their interactions with the vibrational progressions of the excited valence statesBthinsp;2Pgr; andLthinsp;2Pgr;. However, measured spectral lines remain unassigned and spectroscopic results on the higher members of theBandLprogressions and on their interactions with thenppgr; Rydberg series are incomplete. The present work attempts a quantitative representation of the observations in terms of five electronic states with mutual electronic coupling, i.e., a sohyphen;called diabatic basis. The electronic states: two valence statesBandL, and the lowest three Rydberg states of thenppgr; seriesC,K, andQare defined by RKR potential curves, by spinhyphen;orbit coupling constants, by electronic absorption dipole transition moments, and by sixRhyphen;independent electronic valencehyphen;Rydberg interaction energies. The coupling is treated with a vibronic interaction matrix which includes the bound vibrational levels of these five electronic states up to the dissociation limit of theB2Pgr; state, i.e., a total of 69 vibrational levels in each of the two2Pgr; spin doublets and in each of three different isotopes. The calculated results include vibronic energies,Bvalues, absorption oscillator strengths, and, for a few selected levels, detailed rotational structures. Assignments ofvin the vibrational progression of theBstate to observed structures in the spectrum have been extended up tov= 37, i.e., to within 226plusmn;30 cmminus;1of the dissociation limit. The electronic valencehyphen;Rydberg interaction energies are found to decrease along the Rydberg series approximately proportional tonast;minus;3/2. The quantitative relationship between the spectroscopically determined twohyphen;state interaction energies and the corresponding calculated matrix elements is clarified. Assignments of observed features to a vibrational progression of a valence stateLthinsp;2Pgr;iwith a large spinhyphen;orbit coupling constant are confirmed and the positions of unobserved spin components are predicted.
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