Time-resolved kinetic studies on quenching of HCF(A1A'') by alkane and alcohol molecules.
HCF(X1A') radicals were produced by laser photolysis of CHFBr2 at 213 nm and were electronically excited from the ground state to A1A''(030) at 492.7 nm with a dye laser pumped by a Nd:YAG laser. With the analysis of the lifetime of the time-resolved total fluorescence signals collected in the reaction cell where the total pressure was fixed to be 14.0 Torr, the quenching data of HCF(A1A'') by alkane and alcohol molecules at room temperature were derived from variation of pseudo-first-order rate constant with different quencher pressures. It is found that the quenching rate constants are close to the collision rate constants (10(-10) cm3 molecule(-1) s(-1)), indicating the long-range attractive forces between the collision partners play an important role in the entrance channel of quenching process. Several kinetic models were applied to analyze the mechanism of the quenching process. The complex formation cross sections are calculated with the collision complex model. Correlations of the quenching rate constant for the removal of the HCF(A1A'') state with ionization potential of the quenching partners show that the insertion reactive mechanism is probably the dominant reaction channel, which is analogous to the behaviors of other three-atom carbenes in corresponding electronic states.
Yang
Xueliang
X
Open Laboratory of Bond-selective Chemistry, Chinese Academy of Sciences, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026.
Zhang
Weiqing
W
Ji
Min
M
Chen
Yang
Y
Chen
Congxiang
C
D000438:Alcohols / Q000737:chemistry*; D000473:Alkanes / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry / Q000528:radiation effects; D005740:Gases / Q000737:chemistry; D006838:Hydrocarbons / Q000737:chemistry / Q000528:radiation effects; D006846:Hydrocarbons, Halogenated / Q000737:chemistry* / Q000528:radiation effects; D007700:Kinetics; D007834:Lasers; D008027:Light; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry / Q000528:radiation effects; D010782:Photolysis; D013696:Temperature; D013997:Time Factors; D014466:Ultraviolet Rays
D000438:Alcohols; D000473:Alkanes; D005609:Free Radicals; D005740:Gases; D006838:Hydrocarbons; D006846:Hydrocarbons, Halogenated; C520677:fluorodibromomethane; C030011:carbene; D008697:Methane