Measurement of the dipole moments of excited states and photochemical transients by microwave dielectric absorption
- Univ. of Notre Dame, IN
Time-resolved changes in microwave dielectric absorption have been used to study transients formed by laser flash photolysis. Details of the method and apparatus are given. Applications both to the measurements of the dipole moments of transients and to decay kinetics are given. The dipole moments of the lowest triplet states of a number of aromatic compounds (mostly ketones) have been measured in benzene solution at room temperature. States of n..pi..* character generally possess smaller dipole moments than the corresponding ground states while states of ..pi pi..* character (for example, fluorenone) have larger values than the ground state. The triplets of 4-(dimethylamino)benzaldehyde and 4,4'-bis(dimethylamino)benzophenone have rather high values of dipole moment (10.5 and 8.4 D, respectively) showing their charge-transfer character. The triplet state of benzil was found to have zero or near-zero dipole moment, thus confirming that the triplet state is of a transstructure. 7 figures, 1 table.
- OSTI ID:
- 6336144
- Journal Information:
- J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 86:19; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
400500* -- Photochemistry
ALDEHYDES
AMINES
AROMATICS
BENZENE
CHEMICAL REACTION KINETICS
DATA
DIPOLE MOMENTS
ELECTROMAGNETIC RADIATION
ENERGY LEVELS
EXCITED STATES
EXPERIMENTAL DATA
FLUORINATED AROMATIC HYDROCARBONS
HALOGENATED AROMATIC HYDROCARBONS
HYDROCARBONS
INFORMATION
IONIZATION
KETONES
KINETICS
LASER RADIATION
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC SOLVENTS
PHOTOIONIZATION
RADIATIONS
REACTION INTERMEDIATES
REACTION KINETICS
SOLVENTS
TIME DEPENDENCE