1997 Fiscal Year Final Research Report Summary
Development of a kinetic analysis to elucidate the dynamics chemical reactions
| Project/Area Number |
08454181
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical chemistry
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| Research Institution | Niigata University |
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Principal Investigator |
YAMASAKI Katsuyoshi Niigata University, Faculty of Science , Associate Professor, 理学部, 助教授 (90210385)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Reaction rate constant / Vibrational relaxation / Laser-induced fluorescence / Linear analysis |
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| Research Abstract |
A new method has been developed to determine the branching ratios between reactive removal and vibrational relaxation. The method needs information on neither photochemical parameters nor relative detectivities of vibrational levels of interest. We applied the method to analyze the time-dependent profiles of the laser-induced fluorescence (LIF) signals of OH (X^2PI_i, upsiron=OMICRON -4) produced in the reactions O (^1D) +CH_4 and O (^1D) +NH_3. The OH (upsiron) were deteced by LIF excited via A^2SIGMA^+-X^2PI_i transitions of the sequences DELTAupsiron=OMICRON (upsiron^"=0,1, and 2) and DELTAupsiron=-3 (upsiron^"=3 and 4). The rate constants for the reactive removal of OH by CH_4 were determined to be kappa (upsiron=1) =1.8*10^<-13> and kappa (upsiron=2) =1.0*10^<-12> cm^3 molecule^<-1> s^<-1>, and those of OH (upsiron) by NH_3 were kappa upsiron=1) =8.4*10^<-12> and kappa (upsiron=2) =6.4*10^<-11> cm^3 molecule^<-1> s^<-1>. Rate constants for vibrational relaxation of OH (upsiron) +CH_4 * OH (upsiron-1) +CH_4 were kappa (upsiron=1) =4.2*10^<-13> and kappa (upsiron=2) =1.3*10^<-12> cm^3 molecule^<-1> s^<-1>, and those of OH (upsiron) +NH_3 were kappa (upsiron=1) =2.5*10^<-11> and kappa (upsiron=2) =6.4*10^<-11> cm^3 molecule^<-1> s^<-1>. Reactive removal of OH (upsiron=1) by CH_4 was 29 times faster than that for OH (upsiron=OMICRON) ; that of OH (upsiron=1) by NH_3 was accelerated by a factor of 52. The ratio of the reactive removal OH (upsiron=2) /OH (upsiron=1) was 5.6 for the reaction with CH_4, and 7.6 for that with NH_3. It has also been found that reactive processes (reactions) are more enhanced than physical processes (relaxation) by a vibrational excitation. This is the first report on the determination of the branching ratios between chemical reaction and vibrational relaxation.
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