Excitation Frequency Dependence of Ultrafast Photoinduced Charge Transfer Dynamics

Abstract

The dependence of the photoinduced charge transfer rate constant on the pump pulse carrier frequency is shown to be strong, and it is considerably affected by the value of the reorganization energy of low-frequency modes at the stage of excitation. In the area of small values of the reorganization energy, the dependence of the charge transfer rate constant on the pump pulse carrier frequency is strongly nonmonotonic that is caused by vibrational resonances and variation of the initial position of the wave packet on the term of the locally excited state. Increasing the reorganization energy smoothes the dependence. The smoothing is caused by the broadening of the vibrational resonances and their overlapping. The highfrequency vibrational mode excitation typically accelerates the charge transfer in both areas of high and low exergonicity and decelerates it in the vicinity of the Marcus barrierless region.

Semiclassical Theory of Multistage Nonequilibrium Electron Transfer in Macromolecular Compounds in Polar Media with Several Relaxation Timescales

“…In ultrafast photoreactions, on the contrary, the initial distribution in the excited state is generally nonequilibrium and depends both on the energetic parameters of the system and spectral characteristics of the pumping pulse (see, e.g., [ 54 ]).…”

The Efficiency of Photoinduced Intramolecular Charge Separation from the Second Excited State: What Factors Can Control It?

“…At the photoexcitation stage, a part of the absorbed energy is deposited into vibrational degrees of freedom and later converted into heat. It should be noted that, in ultrafast photoreactions, the excess vibrational energy in LES can be partly transferred into CSS, where it dissipates as well. − In reality, vibrational losses can sufficiently reduce the efficiency of photovoltaic device only if monochromatic radiation is used for excitation. Contrary to that, in the case of sunlight, these losses can actually raise the efficiency, albeit indirectly.…”