Excluded volume effect within the continuous model for the fluorescence energy transfer

Area of Science:

• Photochemistry
• Physical Chemistry
• Spectroscopy

Background:

• Electronic energy transfer is crucial in photochemistry and materials science.
• Understanding fluorescence decay dynamics is key to characterizing molecular interactions.
• Existing models often simplify spatial distributions of molecules.

Purpose of the Study:

• To investigate the impact of excluded volume on donor fluorescence intensity decay.
• To develop a more accurate model for electronic energy transfer dynamics.
• To analyze the influence of molecular size and spatial restrictions on energy transfer.

Main Methods:

• Theoretical calculation of ensemble-average fluorescence intensity decay.
• Inclusion of excluded volume effects in the model.
• Analysis of time-dependent decay patterns and identification of crossover phenomena.

Main Results:

• Donor decay exhibits complex time dependence when excluded volume is considered.
• A crossover between two distinct time regimes was identified in the decay.
• The crossover correlates with minimal molecular distance (r(m)) and interaction strength (R(0)).

Conclusions:

• Simplified models like the stretched exponential fail to capture the complexity introduced by excluded volume.
• The "apparent dimensionality" derived from simplified models can be misleading.
• Accurate modeling of electronic energy transfer requires accounting for spatial restrictions and molecular interactions.