High-pressure luminescence studies on the twisted intramolecular charge transfer molecule 4-(N,N-dimethylamino)benzonitrile in polymer matrices
- Univ. of Illinois, Urbana, IL (United States)
We present steady state and time dependent luminescence data from 4-(N,N-dimethylamino)benzonitrile (DMSBN) in solid (PMMA) and poly(methyl methacrylate) (PMMA) and poly(ethyl methacrylate) (PEMA) and steady state data for poly(n-butyl methacrylate) (PBMA) to 100 kbar pressure. The results for PMMA and PEMA were essentially identical. At 1 atm the spectra consist of a strong peak at approximately 27,000 cm[sup [minus]1] and a much weaker one at approximately 24,000 cm[sup [minus]1] assigned to emission from the planar and twisted (twisted intramolecular charge transfer, TICT) singlet states, respectively. A new (phosphorescent) peak grew in rapidly with increasing pressure at approximately 22,500 cm[sup [minus]1] (lower energy peak, LEP). By approximately 20 kbar it was 1.5-2.0 times as intense as the higher energy peak (HEP). Thereafter it decreased in relative intensity by a factor of 2 by 100 kbar. Time dependence measurements gave a rate constant for the HEP of approximately 0.35 ns[sup [minus]1], which increased by a factor of 2 at 100 kbar. In the 22,700 cm[sup [minus]1] region two decays were obtained, one in the inverse nanosecond range and one on the order of inverse seconds. The data could be explained in terms of a model in which the slow steps involved transfer via the TICT triplet to the planar triplet, from which state the phosphorescent emission occurred. 29 refs., 12 figs.
- DOE Contract Number:
- FG02-91ER45439
- OSTI ID:
- 7079635
- Journal Information:
- Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 98:44; ISSN JPCHAX; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
661300 -- Other Aspects of Physical Science-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AROMATICS
CHARGE TRANSPORT
ELECTRONIC STRUCTURE
EMISSION SPECTROSCOPY
ESTERS
LUMINESCENCE
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PHOSPHORESCENCE
PHOSPHORS
PMMA
POLYACRYLATES
POLYMERS
POLYVINYLS
PRESSURE DEPENDENCE
SPECTROSCOPY
STEADY-STATE CONDITIONS
TIME DEPENDENCE
TRANSIENTS