The C 3Π, d 1Π, and e 1Π states of SO

Abstract

The energy region just above the first dissociation limit in SO is investigated by a combination of jet cooled 1+1 multiphoton ionization spectroscopy and ab initio calculations. Two electronic states, the C 3Π and d 1Π states, are found to give sharp, rotationally resolved spectra, and a complete analysis of these is presented for the first time. The potential energy curve for the d 1Π is found to be unusual, with only four bound levels and a maximum that does not correspond to a conventional avoided crossing. Our assignments are supported by ab initio calculations, which also predict the interactions between electronic states from spin–orbit coupling. Experimental evidence for these, in the form of perturbations in the observed spectra and predissociation is discussed. Based on our ab initio calculations we also reassign some previous observations to the e 1Π state.

Extensive theoretical study on electronically excited states and predissociation mechanisms of sulfur monoxide including spin–orbit coupling

“…68 The six singlet states are correlated to the first dissociation channel S( 3 P) , in excellent agreement with experiment. 38 Our calculated R e for the d 1 P state is only 0.0172 Å larger than the experimental value, and the computed x e and x e v e values are also more precise than previous investigations. So, it is expected that we could present Six quintet states also correlate to the first dissociation channel of SO, but none of them has been experimentally observed, and only the (1) 5 P state has been theoretically predicted.…”

“…So, it is expected that we could present Six quintet states also correlate to the first dissociation channel of SO, but none of them has been experimentally observed, and only the (1) 5 P state has been theoretically predicted. 38 The (1) 5 P state is a weakly bound state with a well depth of 0.33 eV. The (1) 5 P state crosses with the (2)…”

The B 3Σ− state of the SO radical

“…The d state was found to be weakly bound, with the highest level being v 0 = 3; the C state supports significantly more vibrational levels although only v 0 = 0 and v 0 = 1 have been observed experimentally. Theoretical calculations on the C state [15,16] show that it undergoes an avoided crossing with a repulsive state at r % 2.05 Å ; this can be seen in Fig. 1.…”

“…Apart from matrix work [11], there is only indirect experimental evidence of the A 0 3 D state [14] and even less is known of the bound 5 P state shown in Fig. 1, which has only been postulated from theoretical calculations [15]. SO is unusual in that two bound states, the C 3 P and d 1 P states, have been found just above the dissociation limit [15], using 1 + 1 multiphoton ionisation spectroscopy.…”

“…1, which has only been postulated from theoretical calculations [15]. SO is unusual in that two bound states, the C 3 P and d 1 P states, have been found just above the dissociation limit [15], using 1 + 1 multiphoton ionisation spectroscopy. The d state was found to be weakly bound, with the highest level being v 0 = 3; the C state supports significantly more vibrational levels although only v 0 = 0 and v 0 = 1 have been observed experimentally.…”