Theory of single molecule emission spectroscopy

Area of Science:

• Physical Chemistry
• Spectroscopy
• Theoretical Chemistry

Background:

• Single molecule spectroscopy provides detailed insights into molecular dynamics.
• Photon counting statistics are crucial for understanding light-matter interactions at the single-molecule level.
• Existing theoretical models sometimes present inconsistencies when describing experimental detection.

Purpose of the Study:

• To develop a general theory and calculation framework for frequency-resolved single molecule photon counting statistics.
• To differentiate between naive photon emission and experimentally realizable photon detection.
• To resolve inconsistencies arising from simplified detection models.

Main Methods:

• Derivation of expressions for the generating function of photon counts.
• Calculation of low-order photon-counting moments for both naive and physical detection.
• Application of the framework to a two-level system and a two-level absorber with spectral diffusion.

Main Results:

• A theoretical framework for predicting photon counting statistics was established.
• Physical detection schemes were shown to resolve inconsistencies found in naive detection models.
• The framework was successfully applied to model molecular dynamics scenarios.

Conclusions:

• The developed theory provides a more accurate description of single molecule photon counting experiments.
• Distinguishing between naive and physical detection is essential for precise theoretical predictions.
• This work advances the understanding of light-matter interactions in complex molecular systems.