Singlet methylene removal by halogen-containing organic species

Hayes, Frances; Lawrance, Warren D.; Staker, Warren S.; King, Keith D.

doi:10.1016/0009-2614(94)01280-6

Cited by 10 publications

(13 citation statements)

References 28 publications

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“…Based on the behaviour of CH 2 and SiH 2 , and on a comparison of the relative rate constants for reaction by these species and GeH 2 , the latter is not expected to react with any of these impurities at a rate that would be detectable in the experiments. 25,29,30 The results of the experiments with D 2 O, which reacts very slowly with GeH 2 , confirm this. Likewise, the reactants used will not be affected by the presence of these impurities.…”

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confidence: 72%

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Rate constants for the gas-phase reactions of germylene with CH3OCH3, CH3OH, CD3OD and D2O at ambient temperature

Alexander

King

Lawrance

2003

Phys. Chem. Chem. Phys.

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Gas-phase rate constants for the reactions of germylene, GeH 2 , with dimethylether (CH 3 OCH 3 ), methanol (CH 3 OH), deuterated methanol (CD 3 OD), and deuterated water (D 2 O), have been determined at ambient temperature (295 K) and total pressures over the range 10-200 Torr of the bath gas SF 6 . The second-order rate constants are pressure dependent up to the maximum pressures investigated. The behaviour of GeH 2 with these reactants is very similar to the behaviour observed for silylene, SiH 2 . Over the same pressure range the GeH 2 reaction rate constants are smaller than those observed for SiH 2 .

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confidence: 72%

“…The experimental system is based on that used in earlier kinetic studies of CH 2 (a ˜1A 1 ), 18,[21][22][23][24][25][26][27][28] SiH 2 16,17 and GeH 2 . 8,9 The experiments were conducted at an ambient temperature of 295 K. Briefly, an excimer laser operating at 193 nm photolyses phenylgermane, PhGeH 3 to produce GeH 2 .…”

Section: Methodsmentioning

confidence: 99%

Rate constants for the gas-phase reactions of germylene with CH3OCH3, CH3OH, CD3OD and D2O at ambient temperature

Alexander

King

Lawrance

2003

Phys. Chem. Chem. Phys.

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“…There is a clear trend for (0,1,0) to show a significantly larger removal rate constant than does (0,0,0) for the fluorinated hydrocarbons. C−F bond insertion has been shown in our previous work to not occur for 1 CH 2 (0,0,0) [22]. The additional energy available in the (0,1,0) case (16.2 kJ mol −1 ) may allow this reaction to become possible, as has been discussed for HF by Wagener and Wagner [15] although, as we discuss below, this is only one of a number of possibilities.…”

Section: Resultsmentioning

confidence: 86%

“…The particular apparatus and techniques used in our studies of singlet methylene have been presented in detail in previous publications describing our (0,0,0) ambient and temperature dependent studies [19,20,[22][23][24][25][26][27]. We here give a brief overview, and provide details relevant to the (0,1,0) experiments.…”

Section: Methodsmentioning

confidence: 97%

“…The second-order decay is obtained from a plot of the pseudo-first-order decay rate constants versus reactant pressure. Typical experimental and fitted traces have been presented in previous publications from this group, as have plots of the pseudo-first-order decay rate constants versus reactant pressure [19,20,[22][23][24][25][26][27]. The experiments are performed at ambient temperature (295 ± 2 K).…”

Section: Methodsmentioning

confidence: 99%

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Singlet Methylene Removal Rate Constants from the (0,1,0) Vibrational Level: Enhancement via Complex-Mediated Vibrational Relaxation

Buntine¹,

Gutsche²,

Staker³

et al. 2001

Zeitschrift Für Physikalische Chemie

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The technique of laser flash photolysis/laser absorption has been used to obtain absolute removal rate constants for singlet methylene, 1 CH 2 (ã 1 A 1 ), from the vibrationally excited (0,1,0) level. (0,1,0) removal rate constants are reported for the 13 species N . With the exception of the slowest three reacting species, CH 4 , CH 3 F and C 2 F 4 , for the species which are known to react from the (0,0,0) level the removal rate constants are essentially identical for the (0,0,0) and (0,1,0) levels. The removal rate constants for CH 4 , CH 3 F and C 2 F 4 increase by factors of 1.2, 2.2 and 1.45 respectively with vibrational excitation to (0,1,0). For the species N 2 , CF 4 , and C 2 F 6 , which do not appear to react from (0,0,0), the removal rate constants are increased in the (0,1,0) state. The increase is very large for N 2 , for which the factor is 4, and is substantial for CF 4 and C 2 F 6 , which show factors of 2.55 and 2.7 respectively. The increased removal rate constants for N 2 and for the fluorine-containing species are attributed to the formation of an association complex between 1 CH 2 (0,1,0) and the partner followed by dissociation to 1 CH 2 (0,0,0) and the partner. We refer to this as complex-mediated vibrational relaxation (CMVR). Removal rate constants for the (0,0,0) level are likely to be in error when experimental conditions allow the simultaneous production of 1 CH 2 (0,1,0) from the methylene precursor and where CMVR, which typically has comparable efficiency to collision induced intersystem crossing, provides a growth term for the (0,0,0) population. The species for which CMVR is likely to be significant are those for which reaction is either absent or a minor pathway and where there are electron-rich centres for the empty orbital of 1 CH 2 to "bind", allowing the formation of a long lived 1 CH 2 -collider complex.

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Günter Scheibe

1996

Ber Bunsenges Phys Chem

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Singlet methylene removal by halogen-containing organic species

Cited by 10 publications

References 28 publications

Rate constants for the gas-phase reactions of germylene with CH3OCH3, CH3OH, CD3OD and D2O at ambient temperature

Rate constants for the gas-phase reactions of germylene with CH3OCH3, CH3OH, CD3OD and D2O at ambient temperature

Singlet Methylene Removal Rate Constants from the (0,1,0) Vibrational Level: Enhancement via Complex-Mediated Vibrational Relaxation

Günter Scheibe

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