Isotope effects in the fragmentation of water: The photodissociation of HOD in the first absorption band
We investigate the photofragmentation of HOD in the first absorption band. Full three-dimensional quantum mechanical calculations on an ab initio excited state potential are presented. They are based on the IOS approximation for the rotational (bending) degree of freedom. The remaining two-dimensional problem is treated exactly using hyperspherical (polar) coordinates. HOD absorption spectra are compared with recently published results for H/sub 2/O and D/sub 2/O. Dissociation of the vibrational ground state favors the production of OD fragments, in agreement with physical intuition. The final vibrational distributions for OH and OD are relatively broad indicating strong final state interaction. They are broader for OD but inverted for OH products. Cross sections for the dissociation of vibrationally excited stretching states are also compared with those for H/sub 2/O and a strong isotope effect is found. The branching ratio depends significantly on the initial vibrational state of the parent molecule. The quantum mechanical results are compared with simple classical calculations and generally very good agreement is found. Within the classical limit all data are readily understandable.
- Research Organization:
- Max-Planck-Institut f uer Stroemungsforschung, 3400 Goettingen, Federal Republic of Germany
- OSTI ID:
- 5182011
- Journal Information:
- J. Chem. Phys.; (United States), Vol. 88:11
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
DEUTERIUM
ISOTOPE EFFECTS
HEAVY WATER
PHOTOLYSIS
WATER
CROSS SECTIONS
DISSOCIATION
VIBRATIONAL STATES
CHEMICAL REACTIONS
DECOMPOSITION
ENERGY LEVELS
EXCITED STATES
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
NUCLEI
ODD-ODD NUCLEI
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
STABLE ISOTOPES
400202* - Isotope Effects
Isotope Exchange
& Isotope Separation