Picosecond photophysical processes in iodoanthracenes
Picosecond photophysical processes in 2- and 9-iodoanthracene in cyclohexane at room temperature were studied by triplet-triplet transient absorption spectroscopy between 420-500 nanometers. For small amounts of excess vibronic energy in S/sub 1/, intersystem crossing from the first excited singlet state into high triplet states T/sub n/ (n > 1) with subsequent internal conversion to T/sub 1/ or dissociation from the upper triplet manifold is suggested as a primary pathway for nonradiative relaxation. Rate constants for the processes were estimated using the results from previous fluorescence studies and the population risetime data for T/sub 1/. Analyses of the photoproducts generated by excitation at two different wavelengths into the first excited singlet state reveal a vibronic level dependence of the photodissociation yield, indicating that photodissociation can proceed via at least two different mechanisms in the iodoanthracenes. Stimulated Raman processes and self-action effects are shown to be primarily responsible for the generation of a picosecond continuum when 532 nm picosecond pulses are focused into a CCl/sub 4/ continuum cell. An experimental assessment of the artifacts introduced by the angular distribution of continuum light on the triplet-triplet absorption spectra of acridine is given and procedures to minimize these effects are suggested.
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 5676355
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ABSORPTION
ABSORPTION SPECTROSCOPY
ACRIDINES
ANTHRACENE
AROMATICS
AZAARENES
AZINES
CARBON TETRACHLORIDE
CHEMICAL REACTIONS
CHEMISTRY
CHLORINATED ALIPHATIC HYDROCARBONS
CONDENSED AROMATICS
DATA
DE-EXCITATION
DECOMPOSITION
ELECTROMAGNETIC RADIATION
ENERGY LEVELS
ENERGY TRANSFER
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXCITED STATES
EXPERIMENTAL DATA
FLUORESCENCE
HALOGENATED ALIPHATIC HYDROCARBONS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
INFORMATION
LUMINESCENCE
NUMERICAL DATA
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
PHOTOLYSIS
PYRIDINES
RADIATIONLESS DECAY
RADIATIONS
RAMAN EFFECT
SELF-ABSORPTION
SPECTROSCOPY
VIBRATIONAL STATES
VISIBLE RADIATION