Optical Absorption of Long Range Electron Transfer Systems in Intense Fields

Effects of strong radiation field on long range electron transfer reactions and the crossover between the nonadiabatic and adiabatic limits are investigated. Dramatic variations of the absorption spectrum as a function of laser intensity were predicted in the nonadiabatic limit by Dakhnovskii, Lubchenko, and Coalson (Phys. Rev. Lett. 1996, 77, 2917). These results are extended by utilizing the interaction picture and Green function technique to calculate the spectrum in the crossover and the adiabatic regions. As the solvation timescale becomes slower, the multiphoton absorption is enhanced, and the dependence of the absorption spectrum on field intensity is supressed, eventually vanishing in the adiabatic limit.