Kinetic and spectroscopic study of triplet state and ionic pathways in the laser-induced photoexcitation of N-ethylcarbazole in fluid solutions

Journal Article · Thu Oct 03 00:00:00 EDT 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100173a008· OSTI ID:7273620

Haggquist, G W; Burkhart, R D ^[1]; Naqvi, K R ^[2]

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1. Univ. of Nevada, Reno (United States)
2. Univ. of Trondheim, Dragvoll (Norway)

When fluid solutions of N-ethylcarbazole (NEC) are irradiated by 308-nm pulses from an excimer laser, transient triplets and ions may be observed in the microsecond time regime. The formation of ions is favored in more polar solvents such as acetonitrile (AcN) and that of triplets in nonpolar solvents such as paraffin oil. The quantum yield of triplet formation from initial excitation is 0.23. Triplet states decay through concurrent first- and second-order channels: the second-order process, triplet-triplet annihilation, leads to formation of excited singlet states with an efficiency of 0.12. Transient carbazolyl cations and anions display double-exponential decays. To account for this behavior, a mechanism involving initial electron donation by the multiply excited chromophore to a nearby NEC molecule or solvent molecule is proposed; subsequent decay occurs primarily by germinate recombination of the resulting ion pair. The quantum yield for cation production is 0.037. Delayed fluorescence is AcN also decays by a double-exponential decay curve with rate constants, suggesting that the emission arises mainly from ion recombination.

• DOE Contract Number: FG08-84ER45107
• OSTI ID: 7273620
• Journal Information: Journal of Physical Chemistry; (United States), Vol. 95:20; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CARBAZOLES
PHOTOCHEMISTRY
ELECTRON TRANSFER
EXPERIMENTAL DATA
IONS
KINETICS
RECOMBINATION
SOLVENTS
AROMATICS
AZAARENES
AZOLES
CHARGED PARTICLES
CHEMISTRY
DATA
HETEROCYCLIC COMPOUNDS
INFORMATION
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
400500* - Photochemistry