Hochanadel, C.J., Sworski, T.J., and Ogren, P.J. (1980)
Ultraviolet Spectrum and Reaction Kinetics of the Formyl Radical
J. Phys. Chem. 1980, 84, 231.
Abstract
A transient ultraviolet absorption attributed to the formyl radical, HCO, was
produced by the flash photolysis of water vapor in the presence of CO. For CO
saturated with H2O at a total pressure of 1 atm, the formation of HCO is complete
within ~60 µs, after which it undergoes second-order decay, with
k/epsilon(230 nm)=(1.5±0.2)E+7 cm/s. During the relatively slow formation
reaction (-167), the competing
reaction (55) is significant. By
employing the H2O+CH4 system as an actinometer to determine the amount of
H2O dissociated by the flash (discussed elsewhere), and by computer modeling the
observed formation and decay of HCO as a function of CO pressure, the following
absolute rate constants were obtained. The molar extinction coefficient
epsilon(HCO, 230 nm)=941±171 cm2/mol.
REACTION RATE COEFFICIENTS SUGGESTED IN THIS WORK:
GRI-Mech
Number
('-' sign
means
reverse) |
Reaction |
Rate Coefficient
A T^n exp(-E/RT) |
Temperature
Range
(K) |
A
(mol,cm3,s) |
n
(T in K) |
E
(cal/mol) |
| -167* |
H + CO + M -> HCO + M |
3.6E+7 |
|
|
298 |
| -167** |
H + CO + M -> HCO + M |
5.8E+7 |
|
|
298 |
| -167*** |
H + CO + M -> HCO + M |
3.8E+7 |
|
|
298 |
| A |
HCO + HCO -> products |
1.4E+10 |
|
|
298 |
| B |
H + HCO -> products |
6.9E+10 |
|
|
298 |
* M = CO, dimensions = cm^6/mol^2 s
** M = CH4, dimensions = cm^6/mol^2 s
*** M = H2, dimensions = cm^6/mol^2 s