Interchannel coupling effects in the valence photoionization of SF6

Abstract

The complex Kohn and polyatomic Schwinger variational techniques have been employed to illustrate the interchannel coupling correlation effects in the valence photoionization dynamics of SF6. Partial photoionization cross sections and asymmetry parameters of six valence subshells (1t1g, 5t1u, 1t2u, 3eg, 1t2g, 4t1u) are discussed in the framework of several theoretical and experimental studies. The complex Kohn results are in rather good agreement with experimental results, indicative of the fact that the interchannel coupling effects alter the photoionization dynamics significantly. We find that the dominant effect of interchannel coupling is to reduce the magnitude of shape resonant cross sections near the threshold and to induce resonant features in other channels to which resonances are coupled. The long-standing issue concerning ordering of the valence orbitals is addressed and confirmed 4t1u (6)1t2g (6)3eg (4)(5t1u (6)+1t2u (6)) 1t1g (6) as the most likely ordering.

Molecular frame photoemission by a comb of elliptical high-order harmonics: a sensitive probe of both photodynamics and harmonic complete polarization state

“…It was proposed 44 that the first step, i.e., strong field ionization involves contributions from multiple electronic channels, while the recombination step is influenced by resonant transitions due to the presence of autoionizing states and shape resonances trapping the recolliding electron for typically hundreds of attoseconds before recombination to the ground state occurs. The specific behavior observed for H15 and H17 was related to the presence of the 5t1u  t2g shape resonance in the A channel that dominates the harmonic emission in this spectral range, as shown by complex Kohn computations of valence PI total cross sections involving strong intercoupling effects 72 . The influence of resonances was then investigated using 2D-TDSE simulations for Ar atoms (see the supplementary information of 38 ), and it was found that they result in a structuring of the returning electron wavepacket and an increase of the perpendicular component of the dipole in the radiative recombination step of the HHG process.…”

Photoionization of few electron systems: a hybrid coupled channels approach

“…While simple single electron models or low dimensional models have been partially successful in explaining laser matter interactions, there have been several cases reported where a more elaborate description of electronic structure becomes important. Some of the examples include inter-channel coupling leading to an enhancement in high harmonic generation (HHG) from xenon [3], modification of angle resolved ionization yield of CO 2 [4] and photoionization cross-sections in SF 6 [5], enhancement in HHG due to participation of doubly excited states in beryllium [6], influence of nuclear motion [7], presence of conical intersections [8] and so on. All these instances need a more involved description of the electronic structure.…”

Vibrational effects in the shape resonant photoionization leading to the A2T1 state of SF6+

“…SF6 is particularly interesting in the context of vibrational effects on shape resonances because photoionization from the valence and inner subshells are dominated by the presence of series of resonant peaks. There are many theoretical and experimental studies of the effects of shape resonances on the photoionization parameters of SF6 [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. It has been confirmed from previous results that there are four prominent shape resonances with symmetries a1g, t1u, t2g, and eg in the photoionization spectra of the valence orbitals of SF6.…”

“…Owing to the significance of shape resonances in the photoionization process, sulphur hexafluoride has been the subject of many important studies in physics and chemistry for few decades [1][2][3][4][5][6][7][8][9][10][11][12]. Photoionization dynamics of valence and core subshells of SF6 is significantly affected by the shape resonances, occurring both below and above the ionization threshold.…”

“…However, the shape resonances in the photoinization spectra can couple several outgoing electron channels, leading to significant changes in photoionization dynamics. Therefore a more accurate study of shape resonance requires inclusion of many-electron correlation effects [4,11]. Similarly, shape resonances can induce coupling between electronic motion and vibrational motion, causing the photoionization parameters to be sensitive to molecular geometry near a shape resonance [15,16].…”