Score: 1.00 |
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| Title: Time-resolved cavity ringdown measurements and kinetic modeling of the pressure dependences of the recombination reactions of SiH2 with the alkenes C2H4 , C3H6 , and t-C4H8 .
| | Author: Friedrichs G Fikri M Guo Y Temps F | | Journal: J Phys Chem A Citation: V : 112 P : 5636-46 Year: 2008 Type: PubMed-not-MEDLINE | | Literature: oryza Field: abstract Doc ID: pub18512897 Accession (PMID): 18512897 | | Abstract: Room-temperature rate constants for the pressure-dependent reactions SiH2 + ethene , propene , and t-butene have been determined at total pressures of 3 . 3 mbar < or = p < or = 300 mbar with Ar as buffer gas .
SiH2 was detected by means of time-resolved cavity ringdown spectroscopy ( CRDS ) , and the deconvolution of ringdown , kinetics , and laser bandwidth effect was accomplished with the extended simultaneous kinetics and ringdown model ( eSKaR ) .
In this way , pseudofirst-order rate constants could be extracted from nonexponential ringdown profiles .
The recombination reactions , including the reaction SiH2 + i-butene , have been modeled based on the simplified statistical adiabatic channel model ( SACM ) and weak collision energy-grained master equation ( ME ) simulations .
The influence of an interfering fast isomerization channel was investigated based on the Rice , Ramsperger , Kassel , Marcus theory ( RRKM ) and was found to be only important for the C2H4 reaction .
Using ab initio energies ( G3 ) and structures ( MP2/6-311G ( d , p ) ) as input parameters for the kinetic models , a consistent description of the pressure and temperature dependences of all four reactions was possible .
In the temperature range 295 K < or = T < or = 600 K , the extrapolated limiting high-pressure rate constants , k ( infinity ) ( C2H4 ) / ( cm ( 3 ) x mol ( -1 ) x s ( -1 ) ) = 1 . 9 x 10 ( 14 ) ( T/K ) ( -0 . 065 ) , k ( infinity ) ( C3H6 ) / ( cm ( 3 ) x mol ( -1 ) x s ( -1 ) ) = 1 . 3 x 10 ( 14 ) ( T/K ) ( 0 . 075 ) , k ( infinity ) ( i-C4H8 ) = 1 . 8 x 10 ( 14 ) cm ( 3 ) x mol ( -1 ) x s ( -1 ) , and k ( infinity ) ( t-C4H8 ) / ( cm ( 3 ) x mol ( -1 ) x s ( -1 ) ) = 4 . 6 x 10 ( 13 ) ( T/K ) ( 0 . 21 ) , are close to the collision number and are more or less temperature independent .
In the case of ethene , probably due to the approximate treatment of rotational effects and/or the interfering isomerization process , the applied model slightly underestimates the falloff and thus yields too high extrapolated rate constants at p < 10 mbar .
| Matching Sentences:
[ Sen. 7, subscore: 1.00 ]: In the temperature range 295 K < or = T < or = 600 K , the extrapolated limiting high-pressure rate constants , k ( infinity ) ( C2H4 ) / ( cm ( 3 ) x mol ( -1 ) x s ( -1 ) ) = 1 . 9 x 10 ( 14 ) ( T/K ) ( -0 . 065 ) , k ( infinity ) ( C3H6 ) / ( cm ( 3 ) x mol ( -1 ) x s ( -1 ) ) = 1 . 3 x 10 ( 14 ) ( T/K ) ( 0 . 075 ) , k ( infinity ) ( i-C4H8 ) = 1 . 8 x 10 ( 14 ) cm ( 3 ) x mol ( -1 ) x s ( -1 ) , and k ( infinity ) ( t-C4H8 ) / ( cm ( 3 ) x mol ( -1 ) x s ( -1 ) ) = 4 . 6 x 10 ( 13 ) ( T/K ) ( 0 . 21 ) , are close to the collision number and are more or less temperature independent .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
Score: 1.00 |
|---|
| Title: Time-resolved cavity ringdown measurements and kinetic modeling of the pressure dependences of the recombination reactions of SiH2 with the alkenes C2H4 , C3H6 , and t-C4H8 .
| | Author: Friedrichs G Fikri M Guo Y Temps F | | Journal: J Phys Chem A Citation: V : 112 P : 5636-46 Year: 2008 Type: PubMed-not-MEDLINE | | Literature: oryza Field: title Doc ID: pub18512897 Accession (PMID): 18512897 | | Abstract: Room-temperature rate constants for the pressure-dependent reactions SiH2 + ethene , propene , and t-butene have been determined at total pressures of 3 . 3 mbar < or = p < or = 300 mbar with Ar as buffer gas .
SiH2 was detected by means of time-resolved cavity ringdown spectroscopy ( CRDS ) , and the deconvolution of ringdown , kinetics , and laser bandwidth effect was accomplished with the extended simultaneous kinetics and ringdown model ( eSKaR ) .
In this way , pseudofirst-order rate constants could be extracted from nonexponential ringdown profiles .
The recombination reactions , including the reaction SiH2 + i-butene , have been modeled based on the simplified statistical adiabatic channel model ( SACM ) and weak collision energy-grained master equation ( ME ) simulations .
The influence of an interfering fast isomerization channel was investigated based on the Rice , Ramsperger , Kassel , Marcus theory ( RRKM ) and was found to be only important for the C2H4 reaction .
Using ab initio energies ( G3 ) and structures ( MP2/6-311G ( d , p ) ) as input parameters for the kinetic models , a consistent description of the pressure and temperature dependences of all four reactions was possible .
In the temperature range 295 K < or = T < or = 600 K , the extrapolated limiting high-pressure rate constants , k ( infinity ) ( C2H4 ) / ( cm ( 3 ) x mol ( -1 ) x s ( -1 ) ) = 1 . 9 x 10 ( 14 ) ( T/K ) ( -0 . 065 ) , k ( infinity ) ( C3H6 ) / ( cm ( 3 ) x mol ( -1 ) x s ( -1 ) ) = 1 . 3 x 10 ( 14 ) ( T/K ) ( 0 . 075 ) , k ( infinity ) ( i-C4H8 ) = 1 . 8 x 10 ( 14 ) cm ( 3 ) x mol ( -1 ) x s ( -1 ) , and k ( infinity ) ( t-C4H8 ) / ( cm ( 3 ) x mol ( -1 ) x s ( -1 ) ) = 4 . 6 x 10 ( 13 ) ( T/K ) ( 0 . 21 ) , are close to the collision number and are more or less temperature independent .
In the case of ethene , probably due to the approximate treatment of rotational effects and/or the interfering isomerization process , the applied model slightly underestimates the falloff and thus yields too high extrapolated rate constants at p < 10 mbar .
| Matching Sentences:
[ Sen. 1, subscore: 1.00 ]: Time-resolved cavity ringdown measurements and kinetic modeling of the pressure dependences of the recombination reactions of SiH2 with the alkenes C2H4 , C3H6 , and t-C4H8 .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
