Reilly, J.P., Clark, J.H., Moore, C.B., and Pimentel, G.C. (1978)
HCO Production, Vibrational Relaxation, Chemical Kinetics, and
Spectroscopy Following Laser Photolysis of Formaldehyde
J. Chem. Phys., 1978, 69, 4381.
Abstract
Formaldehyde vapor was photolysed with a tunable pulsed UV laser. Flash kinetic
absorption spectra of the HCO produced were recorded by intracavity dye laser
spectroscopy with a time resolution of 1 µs. The energy threshold for
radical production was confirmed to be 86±1 kcal/mole. Photolysis at 294.1
nm produced HCO in its ground vibronic state (~2/3) and with one quantum of
vibrational excitation in either the bending (~1/3) or CO stretching (0.1-0.01)
vibrations. Observation of the CO stretching hot band absorptions allowed that
frequency to be determined as 1868.4±1 cm-1. Quantitative, state-resolved
measurements of concentration vs time were made in pure CH2O and in mixtures with
O2, NO, or Ar. The vibrational relaxation rate for the bending vibration of HCO
in collisions with CH2O was (4.3±1)E-12 cm3/molecule s. Reaction rates for
reactions (A) and (168) are shown
below. Approximate rates were determined for the radical-radical reactions (55) and (B).
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) |
| 55 |
H + HCO -> H2 + CO |
3.31E+14 |
|
|
298 |
| 168 |
HCO + O2 -> HO2 + CO |
2.41E+12 |
|
|
298 |
| A |
HCO + NO -> HNO + CO |
8.43E+12 |
|
|
298 |
| B |
HCO + HCO -> CH2O + CO |
3.8E+13 |
|
|
298 |