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 and 500 nm. For small amounts of excess vibronic energy in S, intersystem crossing from the first excited singlet state into higher triplet states T/sub n/ (n > 1) with subsequent internal conversion to T/sub 1/ or dissociation from an 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 least two different wavelengths into the first excited singlet state reveal a vibronic level dependence of the photodissociation yield, indicating at least two different photodissociation mechanisms. 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.
- Research Organization:
- Ames Lab., IA (USA)
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 5862258
- Report Number(s):
- IS-T-1042; ON: DE83016145
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400500* -- Photochemistry
ABSORPTION SPECTRA
AROMATICS
CHEMICAL REACTIONS
CONDENSED AROMATICS
DECOMPOSITION
ELECTROMAGNETIC RADIATION
IRRADIATION
LASER RADIATION
MULTIPLETS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PULSED IRRADIATION
RADIATIONS
SPECTRA
TRANSIENTS
TRIPLETS