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Fluctuations and single molecules
Author(s) -
Plakhotnik Taras
Publication year - 2004
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1560/m671-xh1n-7pf7-ttgf
Subject(s) - chemistry , coherence (philosophical gambling strategy) , bloch equations , excitation , interference (communication) , spectral line , rabi cycle , spectroscopy , oscillation (cell signaling) , coherence time , degree of coherence , atomic physics , molecular physics , computational physics , physics , nuclear magnetic resonance , quantum mechanics , quantum , channel (broadcasting) , biochemistry , electrical engineering , engineering
The fluorescence of single molecules coupled to a thermal bath is studied both experimentally and theoretically. The effect of different fluctuations on the coherence properties of resonance fluorescence is considered first. Coherence is measured in an interference experiment where a single molecule is used as a light source. A standard approach based on the optical Bloch equations apparently provides quite an accurate description of the interference experiment. Systems with long correlation times (where spectra are time dependent on any timescale) are considered next. It is shown that intensity—time—frequency correlation spectroscopy, which provides both high signal‐to‐noise ratio and high time resolution, is very suitable for such a case. The Bloch equations are further tested in an experiment where the shape of an excitation spectral line of a single molecule is accurately measured over six orders of magnitude of the exciting laser power. Significant deviations from the predictions of the Bloch equations are found. The role of critical parameters—the correlation time of the bath, the Rabi oscillation period, and the coupling constant between the bath and the molecule—is discussed. The paper also includes a short general introduction to the methodology of single‐molecule studies.