Polarizability of electronically excited molecular oxygen: theory and experiment

Abstract

Multireference ab initio calculations (by using the extended multiconfiguration quasi-degenerate second-order perturbation theory method XMCQDPT2) have been employed to determine the static polarizabilities for the ground triplet ( ) and two excited singlet (a1Δg and ) electronic states of molecular oxygen. The corrections to polarizabilities for the nuclear zero point motion are also reported. It was revealed that the excitation of an O2 molecule into the lowest singlet electronic states leads to a decrease in its polarizability: the polarizabilities of O2(a1Δg) and O2( ) are smaller (by factors of 0.967 and 0.962, respectively) than that of O2( ). The theoretical results for the state were quantitatively confirmed experimentally employing the diffraction at laser-induced gratings.

Dynamics of Singlet Oxygen Molecule Trapped in Silica Glass Studied by Luminescence Polarization Anisotropy and Density Functional Theory

“…This premise is supported by the negligible Stokes shift in the PL 9 spectra and by calculated close polarizabilities in both states. The polarizability in the excited singlet a state is estimated as ~93% of that in the ground state of O2 in organic solvents 37 and ~95% 37 or 96% 38 for gaseous O 2 .…”

Reaction of the N Atom with Electronically Excited O2 Revisited: A Theoretical Study

“…Dunning’s correlation consistent basis sets with diffuse functions aug-cc-pV X Z (maximum angular momentum quantum numbers X = 2...4) were applied throughout the present study. Note that the use of this general-purpose basis set family is usually sufficient to trace basis set convergence for the excited PESs of small and medium-sized reactive systems. ,,− For convenience, we shall call hereafter the overall ab initio model as XMCQDPT2­(11,9)/aug-cc-pV X Z. All electronic structure calculations were performed using the Firefly QC program package, which is partially based on the GAMESS (US) source code …”

A simple semiempirical model for the static polarizability of electronically excited atoms and molecules

“…[24,25,40,[45][46][47][48][49][50][51][52][53] In this respect, it is not surprising that as a result of numerous experimental and theoretical efforts, a vast body of knowledge on the electric properties of atoms, molecules, atomic and molecular clusters has been gathered to date, [6][7][8]13,20,39,[52][53][54][55][56] but most of these data refer to species in the lowest (ground) electronic states, predominantly populated at low (room) temperature, whereas disappointingly little is known about the effect of electronic excitation on the electrical response properties of multielectron systems. Meanwhile, appreciable electronic excitation of the gaseous components occurs both with thermal heating of gas to high temperatures (e.g., in thermal plasma) and under essentially nonequilib-rium conditions relevant to post-shock [57][58][59][60][61][62][63][64] and expanding nozzle [60,61,65] flows, middle and upper layers of terrestrial and extraterrestrial atmospheres, [57,58,[66][67][68][69] absorption of highpowered laser radiation in gaseous media, [16,57,…”

“…Indeed, electric properties of atoms and molecules in excited electronic states are much less known and less studied (both experimentally and theoretically) than their groundstate counterparts [14,24,[85][86][87][88] albeit these characteristics are of increasing interest for several distinctive issues, e.g., in the design of substances and (meta) materials with extreme nonlinear optical properties, [89][90][91] in understanding the solvatochromic shifts in electronic spectra, [86,[91][92][93] in the interpretation of resonance energy transfer processes and molecular exciton interactions, [14] in optical (mainly, laser) [16,30,94,95] and microwave [96,97] diagnostics of nonequilibrium gas.…”

“…[120][121][122] The point is that only a few of the standard electronic structure methods are generally capable of treating the electronic excitation, [123,124] and among those suitable methods for this purpose, there is no universally accurate technique to cope with all types of excitations and systems of all sizes. [21,122,125] Specifically, a reliable ab initio description of excited electronic states requires, as a rule, abandoning the singledeterminant assumption, [16,85,86,108,123,126] which is commonly used for the evaluation of molecular electric properties in the closed-shell ground states (see, e.g., Refs. [4,[6][7][8]13,17]).…”