Rovibrational Parameters for trans-Nitrous Acid

Guilmot, Jean Michel; Godefroid, Michel; Herman, Michel

doi:10.1006/jmsp.1993.1186

Cited by 62 publications

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“…Reference spectra of HONO ͑centered at 6680 cm −1 , assigned as the 2 1 band of cis-HONO by Guilmot et al 30 ͒ and HONO 2 ͑centered at 6530 cm −1 , assigned as the 2 1 − 9 band by Feierabend et al 31 ͒ are shown in Fig. 8͑b͒.…”

Section: E Experimental Resultsmentioning

confidence: 99%

Role of OH-stretch/torsion coupling and quantum yield effects in the first OH overtone spectrum of cis-cis HOONO

McCoy

Fry

Francisco

et al. 2005

The Journal of Chemical Physics

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A joint theoretical and experimental investigation is undertaken to study the effects of OH-stretch/ HOON torsion coupling and of quantum yield on the previously reported first overtone action spectrum of cis-cis HOONO ͑peroxynitrous acid͒. The minimum energy path along the HOON dihedral angle is computed at the coupled cluster singles and doubles with perturbative triples level with correlation consistent polarized quadruple basis set, at the structure optimized using the triple basis set ͑CCSD͑T͒/cc-pVQZ//CCSD͑T͒/cc-pVTZ͒. The two-dimensional ab initio potential energy and dipole moment surfaces for cis-cis HOONO are calculated as functions of the HOON torsion and OH bond length about the minimum energy path at the CCSD͑T͒/cc-pVTZ and QCISD/ AUG-cc-pVTZ ͑QCISD-quadratic configuration interaction with single and double excitation and AUG-augmented with diffuse functions͒ level of theory/basis, respectively. The OH-stretch vibration depends strongly on the torsional angle, and the torsional potential possesses a broad shelf at ϳ90°, the cis-perp conformation. The calculated electronic energies and dipoles are fit to simple functional forms and absorption spectra in the region of the OH fundamental and first overtone are calculated from these surfaces. While the experimental and calculated spectra of the OH fundamental band are in good agreement, significant differences in the intensity patterns are observed between the calculated absorption spectrum and the measured action spectrum in the 2 OH region. These differences are attributed to the fact that several of the experimentally accessible states do not have sufficient energy to dissociate to OH+ NO 2 and therefore are not detectable in an action spectrum. Scaling of the intensities of transitions to these states, assuming D 0 = 82.0 kJ/ mol, is shown to produce a spectrum that is in good agreement with the measured action spectrum. Based on this agreement, we assign two of the features in the spectrum to ⌬n = 0 transitions ͑where n is the HOON torsion quantum number͒ that are blue shifted relative to the origin band, while the large peak near 7000 cm −1 is assigned to a series of ⌬n = + 1 transitions, with predominant contributions from torsionally excited states with substantial cis-perp character. The direct absorption spectrum of cis-cis HOONO ͑6300-6850 cm −1 ͒ is recorded by cavity ringdown spectroscopy in a discharge flow cell. A single band of HOONO is observed at 6370 cm −1 and is assigned as the origin of the first OH overtone of cis-cis HOONO. These results imply that the origin band is suppressed by over an order of magnitude in the action spectrum, due to a reduced quantum yield. The striking differences between absorption and action spectra are correctly predicted by the calculations.

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Section: E Experimental Resultsmentioning

confidence: 99%

Role of OH-stretch/torsion coupling and quantum yield effects in the first OH overtone spectrum of cis-cis HOONO

McCoy

Fry

Francisco

et al. 2005

The Journal of Chemical Physics

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“…Presumably, the coupling is mediated by the matrix, as this reaction has not been reported in the gas-phase so far [8]. The molecule is extremely well characterized by vibrational and electronic spectroscopy [8][9][10][11][12][13][14][15][16][17][18]. Furthermore, because of its small size, the molecule is particularly suited for theoretical studies on the absolutely highest conceivable level [19][20][21][22], and therefore has prototype character.…”

Section: Introductionmentioning

confidence: 99%

The infrared-driven cis–trans isomerization of nitrous acid HONO III: A mixed quantum–classical simulation

Hamm

2008

Chemical Physics

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The infrared-driven cis-trans isomerization of nitrous acid HONO III: a mixed quantum-classical simulationHamm, P Hamm, P (2008 The infrared-driven cis-trans isomerization of nitrous acid HONO III: a mixed quantum-classical simulation Abstract A mixed quantum-classical simulation of the IR-driven cis-trans isomerization of HONO in a Kr matrix at 30 K is presented, treating the hydrogen atom as quantum particle and the Kr matrix as well as intermolecular degrees of freedom of the ONO-body as classical. A new method is presented to time-propagate the coupled set of equations in a DVR basis in internal spherical coordinates, rather than in laboratory frame fixed cartesian coordinates. In spherical coordinates, a much more precise computation of the weak vibrational couplings is possible using a still manageable basis size. Good qualitative agreement between simulation and experiment is obtained, underestimating relaxation and isomerization rates by a modest factor approximate to 5. Upon matrix fluctuations, frequent curve crossings occur between the initially excited OH-stretch vibration and a closely lying combination mode of torsional and bending coordinate that lead to a transfer of population. The subsequent pathway of energy flow is deduced and discussed within a tier model, where trans-states, that belong to the second tier, are populated through a first tier of states that is composed of combinations of bending and torsional excitations. No specific energy pathway is revealed that would funnel the hydrogen atom directly towards the trans-side, hence the experimentally observed high cis -> trans quantum yield of close to one probably has to be explained in a statistical scenario on a timescale much longer than that of the present simulation. (C) 2007 Elsevier B.V. All rights reserved. The infrared-driven cis-trans isomerization of nitrous acid HONO III: A mixed quantum-classical simulationPeter Hamm Universität Zürich, Winterthurerstr. 190, Switzerland (Dated: December 1, 2008)A mixed quantum-classical simulation of the IR driven cis-trans isomerization of HONO in a Kr matrix at 30 K is presented, treating the hydrogen atom as quantum particle and the Kr matrix as well as intermolecular degrees of freedom of the ONO-body as classical. A new method is presented to time-propagate the coupled set of equations in a DVR basis in internal spherical coordinates, rather than in laboratory frame fixed cartesian coordinates. In spherical coordinates, a much more precise computation of the weak vibrational couplings is possible using a still manageable basis size. Good qualitative agreement between simulation and experiment is obtained, underestimating relaxation and isomerization rates by a modest factor ≈ 5. Upon matrix fluctuations, frequent curve crossings occur between the initially excited OH stretch vibration and a closely lying combination mode of torsional and bending coordinate that lead to a transfer of population. The subsequent pathway of energy flow is deduced and discussed within a tier model, where t...

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“…7. Where experimental gas-phase values are available, 31,32 we find small deviations on the order of a few wavenumbers, hinting to a matrix effect for these anharmonicities ͑just like the vibrational frequencies shift a bit in the matrix͒.…”

Section: Discussionmentioning

confidence: 73%

“…Furthermore we observed that cooling of trans-HONO proceeds through the overtones of one particular mode. Based on the number of quanta we observed and the anharmonic coupling constants available in literature, 7,31,32 we suggested that the "cooling mode" is the ONO bend vibration. This is not the lowest energy mode of the trans isomer but lies Ϸ60 cm −1 above the OH-torsional mode ͑see Table I for the normal mode frequencies of HONO in solid Kr͒.…”

Section: Introductionmentioning

confidence: 76%

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Intramolecular vibrational energy relaxation in nitrous acid (HONO)

Botan

Hamm

2008

The Journal of Chemical Physics

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Intramolecular vibrational energy relaxation (IVR) in nitrous acid (HONO) is studied with the help of ultrafast two-color pump-probe spectroscopy. In a previous paper [V. Botan et al., J. Chem. Phys. 124, 234511 (2006)], it has been observed that trans-HONO cools through a cascade of overtones of one specific mode after pumping the OH stretch vibration. We had suggested that this cooling mode is the ONO bend vibration. Furthermore, molecules that have initially been excited by the OH stretch vibration of cis-HONO and then underwent isomerization follow the same relaxation pathway. In the present study, we extend the investigation of IVR of cis-and trans-HONO to the N=O stretch and HON bend spectral regions, finding further evidence that the bottleneck of trans cooling is indeed the ONO bend vibration. In combination with information on the anharmonic coupling constants of different modes, the energy relaxation dynamics preceding this cooling cascade can also be followed in unprecedented detail. Intramolecular vibrational energy relaxation ͑IVR͒ in nitrous acid ͑HONO͒ is studied with the help of ultrafast two-color pump-probe spectroscopy. In a previous paper ͓V. Botan et al., J. Chem. Phys. 124, 234511 ͑2006͔͒, it has been observed that trans-HONO cools through a cascade of overtones of one specific mode after pumping the OH stretch vibration. We had suggested that this cooling mode is the ONO bend vibration. Furthermore, molecules that have initially been excited by the OH stretch vibration of cis-HONO and then underwent isomerization follow the same relaxation pathway. In the present study, we extend the investigation of IVR of cis-and trans-HONO to the N = O stretch and HON bend spectral regions, finding further evidence that the bottleneck of trans cooling is indeed the ONO bend vibration. In combination with information on the anharmonic coupling constants of different modes, the energy relaxation dynamics preceding this cooling cascade can also be followed in unprecedented detail. Intramolecular vibrational energy relaxation in nitrous acid "HONO…

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Rovibrational Parameters for trans-Nitrous Acid

Cited by 62 publications

References 0 publications

Role of OH-stretch/torsion coupling and quantum yield effects in the first OH overtone spectrum of cis-cis HOONO

Role of OH-stretch/torsion coupling and quantum yield effects in the first OH overtone spectrum of cis-cis HOONO

The infrared-driven cis–trans isomerization of nitrous acid HONO III: A mixed quantum–classical simulation

Intramolecular vibrational energy relaxation in nitrous acid (HONO)

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