Fine structure and centrifugal distortion in the electronic and microwave spectra of O₂and SO

Abstract

The fine structure theory of ~Y. states in diatomic molecules is re-examined with particular emphasis on centrifugal distortion in the triplet splitting parameters. The theoretical results are compared with optical and microwave data for the 3y. ground states of Oz and SO. Excellent agreement is found between theoretical predictions and experimental results concerning the centrifugal distortion in the spin-spin splitting for both O3 and SO. However, in contrast to ab initio calculations this agreement indicates that the second-order contribution to the spin-spin splitting is of minor importance. The theoretical value of the centrifugal distortion in the spin-rotation coupling constant is about twice the experimental one for 03. It is pointed out that a slight transition towards coupling case (c) yields a reasonable explanation for this discrepancy.

The Schumann–Runge Absorption Bands of O2at 670 K and the Spectroscopic Constants of the Ground State,X3Σ−g

“…observed lines of the six main branches are given in Table The Table 1 to the well-known term values of £Љ Å 0 and 1 4 levels of the X 3 S 0 g state (Table 3). This procedure of levels of the ground state (13,14). For all the term values fitting the term values of the lower state is equivalent to determined, the FЉ 2 (0) level, JЉ Å NЉ Å 0, was chosen as fitting the transition frequencies with the upper state molecular constants fixed at a particular set of values.…”

Predissociation of the B Σu−3 state of S2: A coupled-channel model

“…In this latter case, the only nonzero diabatic ETMs are for the parallel transitions between case-(a) basis states, i.e., B 3 Σ − u0 − X 3 Σ − g0 and B 3 Σ − u1 − X 3 Σ − g1 , and the case-(a) rotational matrix elements and phase factors given by Lefebvre-Brion and Field 26 are employed in the calculations. In addition, the F 1 and F 3 sublevels of the ground state are treated approximately by calculating the F 1 (N ) − F 2 (N ) and F 3 (N ) − F 2 (N ) energy splittings using the known X 3 Σ − g spectroscopic constants 12 in a 3 Σ Hamiltonian 39 and assuming that the radial wavefunctions do not vary significantly within the N -triplet structure.…”

The angularly resolved O 1s ion-yield spectrum of O2 revisited

“…This approach would indicate an interaction of a discrete state with a continuum state, and it would suggest an interaction of the bound O 1sσ −1 g ( 4 − g )3pπ u ( 3 Π u ) Rydberg state with the O 1sσ −1 g ( 2 − g )3σ * u ( 3 − u ) core-to-valence excitation, which is the only dissociative state in this energy region. However, such a mixing of states with different Λ would require a spin-orbit interaction which is known to be very small in O 2 38 so this explanation is rather doubtful. In the second approach an additional vibrational progression of low intensity is fitted in the energy region below the spectral feature at 540.23 eV.…”