Tunneling corrections to unimolecular rate constants, with application to formaldehyde
Tunneling corrections to the rate constant for unimolecular reactions in an isolated molecule are treated within the standard transition state (i.e., RRKM) theory of such processes. The microcanonical distribution relevant to the unimolecular case causes tunneling effects to enter in a somewhat more complicated fashion than in the analogous transition-state theory for thermally averaged bimolecular rate constants; e.g., even within the separable approximation they do not enter as simply a multiplicative correction factor. Application of the theoretical expressions to some unimolecular processes (H/sub 2/CO ..-->.. H/sub 2/ + CO, trans-HCOH ..-->.. H/sub 2/CO) of interest in the collisionless photochemistry of formaldehyde indicates that tunneling effects are quite significant for rates of 10/sup 9/ s/sup -1/ or slower. Isotope effects are also considered and seen to be quite interesting. 4 figures, 1 table.
- Research Organization:
- Univ. of California, Berkeley
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5541801
- Journal Information:
- J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 101:23; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
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