Simulation of solvent dynamics effects on the fluorescence of 3-methylindole in water

Pedro L. Muino; Dan Harris; Jerome Berryhill; Bruce S. Hudson; Patrik R. Callis

doi:10.1117/12.58282

1 April 1992 Simulation of solvent dynamics effects on the fluorescence of 3-methylindole in water

Pedro L. Muino, Dan Harris, Jerome Berryhill, Bruce S. Hudson, Patrik R. Callis

Proceedings Volume 1640, Time-Resolved Laser Spectroscopy in Biochemistry III; (1992) https://doi.org/10.1117/12.58282
Event: OE/LASE '92, 1992, Los Angeles, CA, United States

Abstract

The UV absorption and fluorescence of 3-methylindole in water at 300 K has been simulated over periods of 4 to 30 ps in length using a combination of classical molecular dynamics simulations and a spectroscopically calibrated semiempirical molecular orbital method (INDO/S-SCI). The absorption redshift is predicted to be 545 +/- 150 cm^-1 for ¹L_a, and 85 +/- 15 cm^-1 for ¹L_b. The distribution of transition energies due to solvent fluctuations suggests inhomogeneous broadening at lower temperatures of about 2000 cm^-1 for ¹L_a, and 400 cm^-1 for ¹L_b, (fwhm). The large time-dependent shift of the ¹L_a fluorescence was determined both by direct nonequilibrium response to an instantaneous charge redistribution and from the autocorrelation function of the fluctuations of the ¹L_a transition energies from the equilibrated ground state. The two methods gave similar response times, roughly fitting a double exponential with time constants of 17 and 290 fs. The magnitude of the calculated shifts with partial and complete solute polarizability are 3000 and 5000 - 6000 cm^-1, bracketing an experimental estimate of 3800 cm^-1. A connection with perturbation-free energy of solvation ((Delta) A_s) results is made which identifies (Delta) A_s as the average of absorption and fluorescence maximum shifts upon solvation, ($DELTA(nu) _a + (Delta) (nu) _f)/2.

Citation Download Citation

Pedro L. Muino, Dan Harris, Jerome Berryhill, Bruce S. Hudson, and Patrik R. Callis "Simulation of solvent dynamics effects on the fluorescence of 3-methylindole in water", Proc. SPIE 1640, Time-Resolved Laser Spectroscopy in Biochemistry III, (1 April 1992); https://doi.org/10.1117/12.58282

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