Theoretical study of nitrous acid electronic spectrum and photofragmentation

Larrieu, C.; Dargelos, Alain; Chaillet, M.

doi:10.1016/0009-2614(82)83092-3

Cited by 36 publications

(31 citation statements)

References 33 publications

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“…15, shows that the photoprepared 2 1 AЈ state correlates adiabatically to O( 1 D)ϩHONO(X 1 AЈ), not to the somewhat higher energy channel ͑0.63 eV higher vertical energy͒ of triplet HONOϩO( 3 P). 42 We assign the major channel to O( 1 D)ϩHONO(X 1 AЈ) and the minor channel to O( 3 P)ϩHONO(a 3 AЉ).…”

Section: O؉hono Channelsmentioning

confidence: 99%

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The influence of local electronic character and nonadiabaticity in the photodissociation of nitric acid at 193 nm

Myers

Forde

et al. 1997

The Journal of Chemical Physics

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The dissociation of nitric acid upon nb,O →* NO 2 excitation at 193 nm has been studied in a crossed laser-molecular beam apparatus. The primary reaction channels are OHϩNO 2 and OϩHONO. We measure the branching ratio between these two competing processes and determine ͑OHϩNO 2 ͒/͑OϩHONO͒ϭ0.50Ϯ0.05. Our experiments provide evidence of a minor OϩHONO pathway, which we assign to O(3 P) and HONO in its lowest triplet state. The dominant pathway correlates to O(1 D)ϩHONO(X 1 AЈ). The translational energy distributions reveal two distinct pathways for the OHϩNO 2 channel. One pathway produces stable NO 2 fragments in the 1 2 B 2 electronic state. The second pathway produces unstable NO 2 fragments which undergo secondary dissociation to NOϩO. We examine the influence of nonadiabaticity along the OHϩNO 2 reaction coordinate in order to explain the significant branching to this other channel. Finally, we introduce a new method for generating correlation diagrams for systems with electronic transitions localized on one moiety, in which we restrict the changes allowed in remote molecular orbitals along the reaction coordinate. Analysis of previously measured XϩNO 2 photofragment pathways in nitromethane and methyl nitrate provides further support for using a restricted correlation diagram to predict the adiabatic and nonadiabatic product channels.

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Section: O؉hono Channelsmentioning

confidence: 99%

“…The vertical excitation energies shown for the HONO electronic states, which are calculated using the trans conformer, are taken from Ref. 42. The AЈ states are indicated by the solid lines, whereas the AЉ states are indicated by the dashed lines.…”

Section: O؉hono Channelsmentioning

confidence: 99%

The influence of local electronic character and nonadiabaticity in the photodissociation of nitric acid at 193 nm

Myers

Forde

et al. 1997

The Journal of Chemical Physics

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“…It is shown in figure 9. The calculation of Larrieu et al 59 for the molecule HONO has served here as a guideline to build the potential energy diagram of CH 3 ONO, and to locate qualitatively the various potential curves shown in figure 9. The substitution of H by CH 3 to switch from nitrous acid to methyl nitrite does not affect indeed the correlation diagram that relates states of the molecule RONO ͑RϭH or CH 3 ) to states of the fragments RO ϩNO.…”

Section: B the Transient Peakmentioning

confidence: 99%

Observation of an indirect pathway in the femtosecond study of alkyl nitrite photodissociation in the S1 state

Mestdagh

Berdah

Dimicoli

et al. 1995

The Journal of Chemical Physics

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The present work has addressed the question of the dissociation time of four alkyl nitrites upon photoexcitation in the S 1 state ͑methyl nitrite, n-, and t-butyl nitrites and i-amyl nitrite͒. The time resolved Laser Induced Fluorescence technique has been used in the femtosecond regime under bulk conditions. The photodissociation has been initiated at 351 nm by 150 fs pump pulses, and has been probed using a two-photon process at 467 nm by 200 fs pulses. The LIF signal has qualitatively the same shape for the four nitrites: it passes through a transient peak before reaching a plateau. The two-photon process that induces the detected fluorescence is nonresonant for detection of the dissociation product NO through the A←X transition. Conversely, the two-photon process is resonant or quasiresonant for detection of the excited nitrite molecule in the S 1 level before it dissociates. This leads to an enhanced detection efficiency of the non-dissociated excited molecule versus that of the NO fragment. A simple kinetic model has been developed to account for this detection scheme. It shows that the transient peak is observable only if the lifetime of the excited molecule is comparable or larger than the temporal width of the lasers. In that case, the model allows the determination of an effective lifetime of the excited molecule from the measured LIF signal. Lifetimes have been found in the range of 125 fs for the four nitrites investigated. This has allowed us to answer a controversy on the dissociation mechanism of methyl nitrite and to confirm that an indirect pathway exists in the photodissociation of this molecule.

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“…Upon excitation at 355 nm the S state is reached via the promotion of one electron of the lone pair of oxygen to the antibonding orbital. 24 As pointed above,/z is aligned perpendicular to the direction of the dissociative O-N bond. This is consistent with the presumed classification of the 81 S0 as an nrt* perpendicular transition.…”

mentioning

confidence: 95%

“…Photodissociation of TBN at 266 nm takes place through the second absorption band, $2 So, via charge transfer from the (CH3)3CO donor to the NO acceptor and therefore it has been presumed that the transition moment/z is parallel to the CONO plane. 24 The arrival time distribution (Figure 3a) exhibits a characteristic behavior in which the fragment recoils parallel to ! and implies that/z is aligned along the dissociative RO-NO bond and that v tends to point parallel to/z.…”

mentioning

confidence: 99%

Ê‐μ‐V Correlation In One‐Colour Photolysis/Ionization Of Tert‐Butyl Nitrite

et al. 1989

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An anisotropic spatial velocity distribution was observed for NO+ produced following one-color photolysis/ionization of tert-butyl nitrite (TBN) by a pulsed polarized laser at 266, 355 and 532 nm in a time-of-flight mass spectrometer. The dependence of the NO+ fragment mass peak profile on the wavelength and on the polarization was monitored. The most striking feature is the varying fragment peak splitting obtained under the same experimental conditions by changing the laser polarization direction. This phenomenon is a result of the vector correlation between the laser polarization,Ê, at a given wavelength, the electronic transition dipole moment of TBN,μ, and the direction of the NO fragment velocity, v. The dynamics of the photodissociation process and, in particular, its directional properties are discussed in view of these results.

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Theoretical study of nitrous acid electronic spectrum and photofragmentation

Cited by 36 publications

References 33 publications

The influence of local electronic character and nonadiabaticity in the photodissociation of nitric acid at 193 nm

The influence of local electronic character and nonadiabaticity in the photodissociation of nitric acid at 193 nm

Observation of an indirect pathway in the femtosecond study of alkyl nitrite photodissociation in the S1 state

Ê‐μ‐V Correlation In One‐Colour Photolysis/Ionization Of Tert‐Butyl Nitrite

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