Photodissociation of methyl nitrite CH3ONO, butyl nitrite (CH3)3CONO, and the clusters [CH3ONO]n and [(CH3)3CONO]n

Kades, E.; Roesslein, M.; Bruehlmann, U.; Huber, J. Robert

doi:10.1021/j100107a004

Cited by 55 publications

(62 citation statements)

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“…The S 1 state lifetime of 125 fs reported by Mestdagh and co-workers 17 confirms the indirect character of the dissociation process upon photoexcitation to S 1 . The photodissociation of other alkyl nitrites in this absorption band, such as CH 3 CH 2 ONO and (CH 3 ) 3 CONO, 18,19 evidence similar predissociation dynamics.…”

Section: Introductionmentioning

confidence: 78%

Imaging and Scattering Studies of the Unimolecular Dissociation of the BrCH₂CH₂O Radical from BrCH₂CH₂ONO Photolysis at 351 nm

et al. 2014

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We report a study of the unimolecular dissociation of BrCH 2 CH 2 O radicals produced from the photodissociation of BrCH 2 CH 2 ONO at 351/355 nm. Using both a crossed laser-molecular beam scattering apparatus with electron bombardment detection and a velocity map imaging apparatus with tunable VUV photoionization detection, we investigate the initial photodissociation channels of the BrCH 2 CH 2 ONO precursor and the subsequent dissociation of the vibrationally excited BrCH 2 CH 2 O radicals. The only photodissociation channel of the precursor we detected upon photodissociation at 351 nm was O−NO bond fission. C−Br photofission and HBr photoelimination do not compete significantly with O−NO photofission at this excitation wavelength. The measured O−NO photofission recoil kinetic energy distribution peaks near 14 kcal/mol and extends from 5 to 24 kcal/mol. There is also a small signal from lower kinetic energy NO product (it would be 6% of the total if it were also from O−NO photofission). We use the O−NO photofission P(E T ) peaking near 14 kcal/mol to help characterize the internal energy distribution in the nascent ground electronic state BrCH 2 CH 2 O radicals. At 351 nm, some but not all of the BrCH 2 CH 2 O radicals are formed with enough internal energy to unimolecularly dissociate to CH 2 Br + H 2 CO. Although the signal at m/e = 93 (CH 2 Br + ) obtained with electron bombardment detection includes signal both from the CH 2 Br product and from dissociative ionization of the energetically stable BrCH 2 CH 2 O radicals, we were able to isolate the signal from CH 2 Br product alone using tunable VUV photoionization detection at 8.78 eV. We also sought to investigate the source of vinoxy radicals detected in spectroscopic experiments by Miller and co-workers (J. Phys. Chem. A 2012, 116, 12032) from the photodissociation of BrCH 2 CH 2 ONO at 351 nm. Using velocity map imaging and photodissociating the precursor at 355 nm, we detected a tiny signal at m/e = 43 and a larger signal at m/e = 15 that we tentatively assign to vinoxy. An underlying signal in the time-of-flight spectra at m/e = 29 and m/e = 42, the two strongest peaks in the literature electron bombardment mass spectrum of vinoxy, is also apparent. Comparison of those signal strengths with the signal at HBr + , however, shows that the vinoxy product does not have HBr as a cofragment, so the prior suggestion by Miller and co-workers that the vinoxy might result from a roaming mechanism is contraindicated.

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Section: Introductionmentioning

confidence: 78%

Imaging and Scattering Studies of the Unimolecular Dissociation of the BrCH₂CH₂O Radical from BrCH₂CH₂ONO Photolysis at 351 nm

et al. 2014

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“…This has been concluded from the observation of bimodal distributions of the rotational population in the NO photodissociation products. 14,15 However, in a later publication such bimodal rotational distributions have been linked to a second decay channel employing a linear O-NO transition state on the excited state potential energy surface.…”

Section: Separation Of Clusters From Monomersmentioning

confidence: 99%

“…Rotational state distributions were always non-statistical, usually well described by Gaussians that peak at J E 35 9,15 for photolysis via the S 1 state, and at J E 55 for photolysis via the S 2 state. 13 Bimodal distributions were reported in several studies and assigned to either clusters 14,15 or a second dissociation channel. 18 A few studies have been performed on the populations of the L-doublet states.…”

Section: Introductionmentioning

confidence: 96%

“…18 A few studies have been performed on the populations of the L-doublet states. 10,12 Polarization experiments indicate positive alignment of the angular momentum vector (0.31 r A (2) 0 r 0.59) 10,12,14,24 after photolysis from the S 1 state, and negative alignment (A (2) 0 E À0.3) after photolysis from the S 2 state. 12,25 Together these studies indicate that the NO fragment is rotating in the original CONO plane.…”

Section: Introductionmentioning

confidence: 99%

“…Data for specific quantum states following dissociation of jet-cooled nitrites were later obtained by the analysis of Doppler profiles. 12,14,25 A complete analysis via Doppler profiles requires measurements with different propagation directions of photolysis and probe beams. The profiles must be deconvoluted with the laser line width, and usually only monomodal velocity distributions were fitted.…”

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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First Experimental Observation on Different Ionic States of both Methylthio (CH3S.) and Methoxy (CH3O.) Radicals

Zhu

Wang

et al. 2000

Angewandte Chemie

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Photodissociation of methyl nitrite CH3ONO, butyl nitrite (CH3)3CONO, and the clusters [CH3ONO]n and [(CH3)3CONO]n

Cited by 55 publications

References 5 publications

Imaging and Scattering Studies of the Unimolecular Dissociation of the BrCH₂CH₂O Radical from BrCH₂CH₂ONO Photolysis at 351 nm

Imaging and Scattering Studies of the Unimolecular Dissociation of the BrCH₂CH₂O Radical from BrCH₂CH₂ONO Photolysis at 351 nm

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

First Experimental Observation on Different Ionic States of both Methylthio (CH3S.) and Methoxy (CH3O.) Radicals

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Photodissociation of methyl nitrite CH3ONO, butyl nitrite (CH3)3CONO, and the clusters [CH3ONO]n and [(CH3)3CONO]n

Cited by 55 publications

References 5 publications

Imaging and Scattering Studies of the Unimolecular Dissociation of the BrCH2CH2O Radical from BrCH2CH2ONO Photolysis at 351 nm

Imaging and Scattering Studies of the Unimolecular Dissociation of the BrCH2CH2O Radical from BrCH2CH2ONO Photolysis at 351 nm

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

First Experimental Observation on Different Ionic States of both Methylthio (CH3S.) and Methoxy (CH3O.) Radicals

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Imaging and Scattering Studies of the Unimolecular Dissociation of the BrCH₂CH₂O Radical from BrCH₂CH₂ONO Photolysis at 351 nm

Imaging and Scattering Studies of the Unimolecular Dissociation of the BrCH₂CH₂O Radical from BrCH₂CH₂ONO Photolysis at 351 nm