Photodissociation of jet-cooled methyl and t-butyl nitrite near 380 nm

Hippler, Michael; Al-Janabi, F.A.H.; Pfab, Josef

doi:10.1016/0009-2614(92)85448-j

Cited by 43 publications

(27 citation statements)

References 16 publications

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“…This is in accordance with previous studies 8,10,12,30,31 by absorption spectroscopy and LIF both in bulb and molecular beams. The majority of the NO fragments is formed in the v = 0 and v = 1 vibrational states with a maximum of the rotational populations near j = 59.5.…”

Section: Resultssupporting

confidence: 94%

“…For other nitrites like CH 3 ONO 20,65 a direct dissociation on a purely repulsive potential energy surface and a competition between adiabatic and non-adiabatic decays caused by a barrier along the reaction coordinate have been discussed as alternative scenarios. 8,14 In the case of t-BuONO the evidence from our data points towards the first alternative: regardless of the vibrational state k in the S 1 state that is initially excited, the fraction of excess energy converted to kinetic energy is almost constant at 46%. Also, the rotational population distribution of the NO fragments does not depend on k, nor does it depend on the vibrational level v monitored.…”

Section: Mechanism Of Photodissociationmentioning

confidence: 62%

“…By application of these techniques a wealth of information has been gathered on the photodissociation dynamics of alkyl nitrites, in particular for methyl nitrite CH 3 ONO 1-8 and t-BuONO. [8][9][10][11][12][13][14][15][16][17][18][19] Reviews of this earlier work can be found in ref. 20 and 21. In spite of this there are two good reasons for further studies on this class of compounds.…”

Section: Introductionmentioning

confidence: 99%

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Photodissociation dynamics of tert-butylnitrite following excitation to the S1 and S2 states. A study by velocity-map ion-imaging and 3D-REMPI spectroscopy

Wenge

Schmaunz

Kensy

et al. 2012

Phys. Chem. Chem. Phys.

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Excitation of tert-butylnitrite into the first and second UV absorption bands leads to efficient dissociation into the fragment radicals NO and tert-butoxy in their electronic ground states 2 P and 2 E, respectively. Velocity distributions and angular anisotropies for the NO fragment in several hundred rotational and vibrational quantum states were obtained by velocity-map imaging and the recently developed 3D-REMPI method. Excitation into the well resolved vibronic progression bands (k = 0, 1, 2) of the NO stretch mode in the S 1 ' S 0 transition produces NO fragments mostly in the vibrational state with v = k, with smaller fractions in v = k À 1 and v = k À 2. It is concluded that dissociation occurs on the purely repulsive PES of S 1 without barrier. All velocity distributions from photolysis via the S 1 (np*) state are monomodal and show high negative anisotropy (b E À1). The rotational distributions peak near j = 30.5 irrespective of the vibronic state S 1 (k) excited and the vibrational state v of the NO fragment. On average 46% of the excess energy is converted to kinetic energy, 23% and 31% remain as internal energy in the NO fragment and the t-BuO radical, respectively. Photolysis via excitation into the S 2 ' S 0 transition at 227 nm yields NO fragments with about equal populations in v = 0 and v = 1. The rotational distributions have a single maximum near j = 59.5. The velocity distributions are monomodal with positive anisotropy b E 0.8. The average fractions of the excess energy distributed into translation, internal energy of NO, and internal energy of t-BuO are 39%, 23%, and 38%, respectively. In all cases B8500 cm À1 of energy remain in the internal degrees of freedom of the t-BuO fragment. This is mostly assigned to rotational energy. An ab initio calculation of the dynamic reaction path shows that not only the NO fragment but also the t-BuO fragment gain large angular momentum during dissociation on the purely repulsive potential energy surface of S 2 .

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Section: Resultssupporting

confidence: 94%

Section: Mechanism Of Photodissociationmentioning

confidence: 62%

Section: Introductionmentioning

confidence: 99%

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Photodissociation dynamics of tert-butylnitrite following excitation to the S1 and S2 states. A study by velocity-map ion-imaging and 3D-REMPI spectroscopy

Wenge

Schmaunz

Kensy

et al. 2012

Phys. Chem. Chem. Phys.

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“…Notation is 1.6(−1)=1.6×10 −1 a Sander et al (2000) Gierczak et al (1998) and Warneck (2001) g quantum yield assumed equal to the wavelength-dependent quantum yields of acetone multiplied by a factor 1.2, in order to match the averaged yield measured by Raber et al (1995) h assumed equal to the wavelength-dependent quantum yields of CH 3 CHO for the different photodissociation paths, adjusted to match the averaged yield reported by Bacher et al (2001) Hippler et al (1992) been estimated based on assumed simple relationships between the photolytic parameters of compounds of similar structures. Table 5 summarizes the reactions and rates for the species of interest in this study.…”

Section: Photolysismentioning

confidence: 99%

Alpha-pinene oxidation by OH: simulations of laboratory experiments

et al. 2004

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Abstract. This paper presents a state-of-the-art gas-phase mechanism for the degradation of α-pinene by OH and its validation by box model simulations of laboratory measurements. It is based on the near-explicit mechanisms for the oxidation of α-pinene and pinonaldehyde by OH proposed by Peeters and co-workers. The extensive set of α-pinene photooxidation experiments performed in presence as well as in absence of NO by Nozière et al. (1999a) is used to test the mechanism. The comparison of the calculated vs measured concentrations as a function of time shows that the levels of OH, NO, NO 2 and light are well reproduced in the model. Noting the large scatter in the experimental results as well as the difficulty to retrieve true product yields from concentrations data, a methodology is proposed for comparing the model and the data. The model succeeds in reproducing the average apparent yields of pinonaldehyde, acetone, total nitrates and total PANs in the experiments performed in presence of NO. In absence of NO, pinonaldehyde is fairly well reproduced, but acetone is largely underestimated.The dependence of the product yields on the concentration of NO and α-pinene is investigated, with a special attention on the influence of the multiple competitions of reactions affecting the peroxy radicals in the mechanism. We show that the main oxidation channels differ largely according to photochemical conditions. E.g. the pinonaldehyde yield is estimated to be about 10% in the remote atmosphere and up to 60% in very polluted areas. We stress the need for additional theoretical/laboratory work to unravel the chemistry of the primary products as well as the ozonolysis and nitrateinitiated oxidation of α-pinene.

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“…The UV photolysis of methyl nitrite (MeONO) provides one such opportunity to explore solvent effects because there is an extensive body of prior experimental and theoretical work on its gasphase photolysis, albeit with some controversy about the precise dissociation mechanism(s) [3][4][5][6][7][8][9][10][11][12][13]. Here, we present observations of the ultrafast dissociation and geminate recombination dynamics of MeONO dissolved in a liquid perfluorocarbon (PFC).…”

Section: Introductionmentioning

confidence: 99%

Conformer-specific geminate recombination following methyl nitrite photolysis in solution

Coulter

Grubb

Orr-Ewing

2017

Chemical Physics Letters

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms UV excitation in the structured S1  S0 absorption band induces dissociation, with geminate recombination and vibrational cooling of syn and anti-conformers of methyl nitrate on a timescale of ~56 ps. Solvent-induced vibrational cooling favours relaxation to the higher-energy anti-conformer on entropic grounds, and subsequent inter-conversion to the lower-energy synconformer is prevented by a 3500 cm -1 barrier. UV excitation to the 2 state produces a transient electronic absorption band resembling the absorption spectrum of NO2.

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Photodissociation of jet-cooled methyl and t-butyl nitrite near 380 nm

Cited by 43 publications

References 16 publications

Photodissociation dynamics of tert-butylnitrite following excitation to the S1 and S2 states. A study by velocity-map ion-imaging and 3D-REMPI spectroscopy

Photodissociation dynamics of tert-butylnitrite following excitation to the S1 and S2 states. A study by velocity-map ion-imaging and 3D-REMPI spectroscopy

Alpha-pinene oxidation by OH: simulations of laboratory experiments

Conformer-specific geminate recombination following methyl nitrite photolysis in solution

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