Direct photodissociation of SO+ via the 14Σ+ state

Abstract

The direct photodissociation process SO + a 41I + h v ~ S + (4S°)+ O(3P) via the repulsive SO + 1 42+ state has been studied using a laser-ion photofragment spectrometer with coaxial beams. The kinetic energy distribution of the S + photofragments has been measured at a laser wavelength of 2 = 488 nm (h v = 2.54 eV). The spectrum shows vibrational structure which can be assigned to transitions from the vibrational levels v=7-13 of the initial a 4//state. The experimental data are used along with semi-empirical calculations to locate the potential curve of the repulsive 1 4Z+ state in the Franck-Condon region. The results are compared with data obtained from photopredissociation studies of SO + and with theoretical calculations for the 1 42 + state.

Photofragment spectroscopy of SO+ in the wavelength range from 308–514.5 nm

“…The energies are given relative to the SO probed by the present measurements (R = 3.0-4.5 %), The deviation from the calculated curve of Cossart et al is not too surprising, since the purpose of their ab initio calculations was not to achieve the most accurate state energies, but rather to obtain information about the approximate location of unobserved states in order to study the possible influence of these states on the interpretation of their measurements. The 1 42;+ potential curve presented here is slightly lower than our former result [18], but still falls within the estimated range of uncertainty of our previous work. In the present measurements, the assignment of the vibrational levels is different from the previous one by one quantum.…”

“…As already discussed in our earlier work [18], the photofragments with a released kinetic energy around W=leV result from the process SO + a4H(v)+hv ---+S + (4SO)@O(3p) via the repulsive SO + 1 427+ state.…”

“…The predissociation mechanism of the b 4~--state was attributed to spin-orbit coupling to the repulsive 1 427 ~-state. In a previous paper from this laboratory [ 18], we have reported on the study of the direct photodissociation process SO + + hv-~S + + O using a laser-ion photofragment spectrometer with coaxial beams. The kinetic energy distribution of the S + photofragments was measured at a laser wavelength resolved structure brational levels of state.…”

A theoretical characterization of the quartet states of the SO+ molecular ion

“…2, the assumption made by Andrić et al 15 and Bissantz et al 16 of a constant transition dipole moment function in the calculation of the absorption cross section for direct photodissociation is not actually valid. In the region around R e of the a state, the moment is very small (Ϸ0.01 a.u.…”

“…9 as ͑1,1͒ to bring both spectroscopic data into mutual concordance. In recent ion photofragment experiments Andrić et al 15 and Bissantz et al 16 have investigated the direct photodissociation process SO ϩ (a 4 ⌸)ϩh →S ϩ ϩO via the 1 4 ⌺ ϩ state, thus characterizing for the first time the potential energy curve of the repulsive 1 4 ⌺ ϩ state. Very recently, additional insights into the photoelectron spectra of the SO molecule have been gained by Dyke et al 17 using synchrotron radiation.…”