Oxygen spectroscopy below 5.1 eV

The lowest five 1 AЈ states of ozone, involved in the photodissociation with UV light, are analyzed on the basis of multireference configuration interaction electronic structure calculations with emphasis on the various avoided crossings in different regions of coordinate space. Global diabatic potential energy surfaces are constructed for the lowest four states termed X, A, B, and R. In addition, the off-diagonal potentials that couple the initially excited state B with states R and A are constructed to reflect results from additional electronic structure calculations, including the calculation of nonadiabatic coupling matrix elements. The A/X and A/R couplings are also considered, although in a less ambitious manner. The photodissociation dynamics are studied by means of trajectory surface hopping ͑TSH͒ calculations with the branching ratio between the singlet, O͑ 1 D͒ +O 2 ͑ 1 ⌬ g ͒, and triplet, O͑ 3 P͒ +O 2 ͑ 3 ⌺ g − ͒, channels being the main focus. The semiclassical branching ratio agrees well with quantum mechanical results except for wavelengths close to the threshold of the singlet channel. The calculated O͑ 1 D͒ quantum yield is approximately 0.90-0.95 across the main part of the Hartley band, in good agreement with experimental data. TSH calculations including all four states show that transitions B → A are relatively unimportant and subsequent transitions A → X / R to the triplet channel are negligible.

“…State AЈ 3 ⌬ u is one of the Herzberg states of oxygen. 29 Another one, A 3 ⌺ u + , which is higher by only 630 cm −1 , does not appear in Fig. 5.…”

Section: Electronic Structure Calculations and Overview Of Potentmentioning

confidence: 87%

Photodissociation of ozone in the Hartley band: Potential energy surfaces, nonadiabatic couplings, and singlet/triplet branching ratio

Schinke

McBane

2010

“…Three of these states are very well characterized by extensive spectroscopic studies [1][2][3][4][5][6][7][8][9][10][11] of the so-called Herzberg bands, bands corresponding to transitions from the X 3 ⌺ g Ϫ ground state to the A 3 ⌺ u ϩ ͑Herzberg I͒, c 1 ⌺ u Ϫ ͑Herzberg II͒, and AЈ 3 ⌬ u ͑Herzberg III͒ states. The other five ungerade states, 1 3 ⌸ u , 1 5 ⌺ u Ϫ , 1 5 ⌸ u , 1 1 ⌸ u , and 2 3 ⌺ u ϩ , are difficult to detect because these potentials have only shallow minim at large internuclear separations (rϾ5a 0 ), which leads to very unfavorable Franck-Condon overlap with the ground state that has an r 0 ϭ2.29a 0 .…”

Section: Introductionmentioning

confidence: 99%

Reassignment of the O2 spectrum just below dissociation threshold based on ab initio calculations

Vroonhoven

Groenenboom

2002

Vibrational Herzberg bands of the O 2 molecule just below its first O( 3 P)ϩO( 3 P) dissociation limit are since long-known to be perturbed. Jenouvrier et al. ͓J. Mol. Spectrosc. 198, 136 ͑1999͔͒ assigned the cause of the perturbations to five vibrational levels supported by the shallow minimum in the 1 3 ⌸ u potential energy curve around 5.5a 0 . Using ab initio potential energy curves and spin-orbit couplings from previous work ͓J. Chem. Phys. 116, 1954 ͑2002͔͒ we present a full quantum calculation of all ungerade rotation-vibration-electronic states of oxygen just below the dissociation threshold, through a total angular momentum quantum number of Jϭ19. This calculation shows that the original assignment, based on a Hund's case ͑a͒ model of a regular 1 3 ⌸ u multiplet was not correct. Based on our calculation we present a new assignment of the perturbing states: 1 3 ⌸ u,⍀ϭ2 (vϭ0͒, 1 3 ⌸ u,1 ͑0͒, 1 3 ⌸ u,2 ͑1͒, 1 3 ⌸ u,1 ͑1͒, and 1 3 ⌸ u,0 Ϫ͑0͒ in order of ascending term values. We show the new assignment to be consistent with experimental data and we also propose new spectroscopic parameters for the perturbing states.

“…This metastability allows the oxygen molecule to provide a significant reservoir of energy in chemical reactions and photochemistry in the atmosphere, and at the same time, it greatly impedes the spectroscopic study of the oxygen molecule. 4 The a 1 ⌬ g state of oxygen is important in biological chemistry and the b 1 ⌺ g + state appears in afterglow, dayglow, nightglow, and in auroras. 4 These six lowest bound electronic states have been studied experimentally and theoretically.…”

Section: Introductionmentioning

confidence: 99%

“…4 The a 1 ⌬ g state of oxygen is important in biological chemistry and the b 1 ⌺ g + state appears in afterglow, dayglow, nightglow, and in auroras. 4 These six lowest bound electronic states have been studied experimentally and theoretically. Experimental characterization of these six bound states can be found in the literature.…”

Section: Introductionmentioning

confidence: 99%

“…Experimental characterization of these six bound states can be found in the literature. 4,5 Many theoretical calculations for these six bound states have also been published in the literature; Schaefer and Harris 6 as well as Beebe et al 7 using configuration interaction ͑CI͒ method with minimum basis sets studied these six bound states and many other electronic states. Furthermore, Schaefer 8 using a larger basis set and an extensive CI method calculated the potential energy curve of the X 1 ⌺ u − ground state.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Time-dependent density functional study of the electronic potential energy curves and excitation spectrum of the oxygen molecule

Guan

Wang

Ziegler

et al. 2006

Time-dependent density functional study of the electronic potential energy curves and excitation spectrum of the oxygen molecule Article (Unspecified) http://sro.sussex.ac.uk Guan, Jingang, Wang, Fan, Ziegler, Tom and Cox, Hazel (2006) Time-dependent density functional study of the electronic potential energy curves and excitation spectrum of the oxygen molecule. Journal of Chemical Physics, 125 (4). p. This version is available from Sussex Research Online: http://sro.sussex.ac.uk/583/ This document is made available in accordance with publisher policies and may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the URL above for details on accessing the published version. Copyright and reuse:Sussex Research Online is a digital repository of the research output of the University.Copyright and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable, the material made available in SRO has been checked for eligibility before being made available.Copies of full text items generally can be reproduced, displayed or performed and given to third parties in any format or medium for personal research or study, educational, or not-for-profit purposes without prior permission or charge, provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way.Time-dependent density functional study of the electronic potential energy curves and excitation spectrum of the oxygen molecule Orbital energies, ionization potentials, molecular constants, potential energy curves, and the excitation spectrum of O 2 are calculated using time-dependent density functional theory ͑TDDFT͒ with Tamm-Dancoff approximation ͑TDA͒. The calculated negative highest occupied molecular orbital energy ͑− HOMO ͒ is compared with the energy difference ionization potential for five exchange correlation functionals consisting of the local density approximation ͑LDAxc͒, gradient corrected Becke exchange plus Perdew correlation ͑B 88X +P 86C ͒, gradient regulated asymptotic correction ͑GRAC͒, statistical average of orbital potentials ͑SAOP͒, and van Leeuwen and Baerends asymptotically correct potential ͑LB94͒. The potential energy curves calculated using TDDFT with the TDA at internuclear distances from 1.0 to 1.8 Å are divided into three groups according to the electron configurations. The 1 u 4 1 g 2 electron configuration gives rise to the X 3 ⌺ g − , a 1 ⌬ g , and b 1 ⌺ g + states; the 1 u 3 1 g 3 electron configuration gives rise to the c 1 ⌺ u − , C 3 ⌬ u , and A 3 ⌺ u + states; and the B 3 ⌺ u − , A 1 ⌬ u , and f 1 ⌺ u + states are determined by the mixing of two or more electron configurations. The excitation spectrum of the oxygen molecule, calculated with the aforementioned exchange correlation functionals, shows that ...