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Richard D. Burkhart

Professor Emeritus

Contact Information

Degrees

  • Ph.D. (1960), University of Colorado
  • A.B. (1956), Dartmouth College

Research Interests

Our research is centered upon photophysical processes involving pure and molecularly doped polymers. Since polymers are potentially useful materials for optoelectronic devices or solar energy applications, characterization of their light-induced properties is of considerable interest both in the solid state and in solution. We use high powered excimer lasers or tunable dye lasers as the excitation source and luminescence spectra are recorded using diode arrays. We normally use time resolution in the nanosecond to microsecond regime. Typical data are represented by the luminescence spectrum for poly(N-vinylcarbazole) in fluid solution included on this page. The spectral and temporal characterization of short-lived transients is also accomplished using a laser pump followed by a photochromatic probe. An example of this type of spectrum for 3,6-dibromocarbazole is also included on this page. The transient intermediates with which we normally deal are either triplet states or radical ions and a major emphasis is upon learning the fate of these species. Of course, ion recombination is important as well as radiative and radiationless deactivation of excited states. But energy transfer and migration also play a role as well as annihilative events. Our goal is to learn how rates and direction of energy transfer can be controlled by combining chemical modification of the polymers with instrumental techniques. This knowledge base is required for the rational design of polymer based electronic devices.

Publications

  • Ganguly, T.; Burkhart, R.D. Some photophysical properties of electronically excited phenldibenzophosphole in rigid polymer matrices. J. Phys. Chem. A 1997, 101, 5633-5639.
  • Tsuchida, A.; Yamamoto, M.; Liebe, W.R.; Burkhart, R.D.; Tsubakiyama, K. Triplet energy migration in poly(4-methacryloylbenzophenone-co-methyl methacrylate) films: Temperature dependence and chromophore concentration dependence. Macromolecules 1996, 29, 1589-1594.
  • Haggquist, G.W.; Burkhart, R.D. Triplet photophysics of multichromophoric molecules. A study of poly(N-vinylcarbazole) and meso-2,4-dicarbazolylpentane in fluid solutions. Macromolecules 1995, 28, 2465-2471.
  • Ganguly, T.; Burkhart, R.D. Computer-assisted resolution of transient absorption bands of phenyldibenzophosphole in fluid solution. Further evidence for triplet excimers. Chem. Phys. Lett. 1994, 226, 552-558.
  • Burkhart, R.D.; Jhon, N.I. Triplet excimer-monomer equilibria as structural probes in pure and molecularly doped polymers. In Structure-Property Relations in Polymers; Urban, M.W., Craver, C.D., Eds.; Advances in Chemistry Series No. 236: 1993; p 599.
  • Haggquist, G.W.; Burkhart, R.D. Photophysics of N-ethylcarbazole in fluid solution. Evidence for solvent dependence and triplet excimer formation. J. Phys. Chem. 1993, 97, 2576.
  • Naqvi, K.R.; Haggquist, G.W.; Burkhart, R.D.; Sharma, D.K. Evaluation of a squirrel-cage photomultiplier base of time-resolved spectroscopy with low-repetition pulses. Rev. Sci. Instrum. 1992, 63, 5806.
  • Haggquist, G.W.; Burkhart, R.D. The influence of laser induced photoion production in polymer photophysics. Polymer Reprints 1992, 33, 841.
  • Burkhart, R.D.; Jhon, N.I.; Boileau, S. An investigation of binding energies of triplet excimers in carbazolyl-containing polymers. Macromolecules 1991, 24, 9310.
  • Haggquist, G.W.; Burkhart, R.D.; Naqvi, K.R. Kinetic and spectroscopic study of triplet state and ionic pathways in the laser-induced photoexcitation of N-ethylcarbazole in fluid solution. J. Phys. Chem. 1991, 95, 7588.

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