Resonance Raman and molecular orbital studies of the effects of deuteration on the vibrational structure of the p-benzosemiquinone radical anion
Deuterium substitution of the p-benzosemiquinone radical anion results in decreases of 23 and 317 cm/sup -1/ in the vibrational frequencies of its totally symmetric ring stretching (Wilson 8a) and C-H bending (9a) modes as observed by resonance-enhanced Raman methods. Ab initio molecular orbital calculations corroborate the vibrational assignments and predict decreases of a similar magnitude. Both the experimental and theoretical studies show that the bands associated with the CO stretching and C-C-C bending vibrations are affected to only a very minor extent by deuteration, i.e., that there is very little contribution from local modes involving hydrogen motion. The symmetrical ring breathing (1) and C-H stretching (2) modes are not resonance enhanced and not observed in the Raman experiments. Of particular note is the Raman band at the ring stretching frequency of the deuterated radical which is considerably broader than the other lines in H/sub 2/O and partially resolved into two lines in D/sub 2/O. This feature is tentatively interpreted as being due to an accidental near degeneracy with the combination of the 9a and 1 modes. Deuteration of the radical somewhat simplifies its optical absorption spectrum in the region of 400-410 nm indicating that the frequency of the 9a vibration in the excited state is decreased in much the same way as in ground state.
- Research Organization:
- Univ. of Notre Dame, IN
- OSTI ID:
- 6855977
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 87:26
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BENZOQUINONES
EXCITATION
LABELLING
PHOTOCHEMICAL REACTIONS
RAMAN SPECTRA
DEUTERIUM
ISOTOPIC EXCHANGE
ANIONS
AQUEOUS SOLUTIONS
CHEMICAL REACTION KINETICS
COMPARATIVE EVALUATIONS
COMPUTER CALCULATIONS
DATA ANALYSIS
DEUTERIUM COMPOUNDS
ELECTRON SPIN RESONANCE
ELECTRONIC STRUCTURE
EXPERIMENTAL DATA
HARTREE-FOCK METHOD
HEAVY WATER
LASER RADIATION
OXIDATION
PH VALUE
PHOTOIONIZATION
QUANTITY RATIO
SAMPLE PREPARATION
TIME DEPENDENCE
AROMATICS
CHARGED PARTICLES
CHEMICAL REACTIONS
DATA
DISPERSIONS
ELECTROMAGNETIC RADIATION
ENERGY-LEVEL TRANSITIONS
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
INFORMATION
IONIZATION
IONS
ISOTOPES
KINETICS
LIGHT NUCLEI
MAGNETIC RESONANCE
MIXTURES
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXYGEN COMPOUNDS
QUINONES
RADIATIONS
REACTION KINETICS
RESONANCE
SOLUTIONS
SPECTRA
STABLE ISOTOPES
WATER
400303* - Organic Chemistry- Isotope Exchange & Isotope Separation- (-1987)
400302 - Organic Chemistry- Isotope Effects- (-1987)