Presentation
13 March 2024 New quantum mechanical effect, resembling Herzberg-Teller coupling, explains the structure of the two-photon absorption spectra of dyes and fluorescent proteins
Author Affiliations +
Abstract
Previously we have found that the two-photon absorption (2PA) spectra of red fluorescent proteins have enhanced vibronic transitions and are about twofold broader, compared to the corresponding one-photon absorption (1PA) spectra. We explained these observations by the dependence of the permanent dipole moment change (Deltamu) on a particular vibrational coordinate (in the Herzberg-Teller spirit). Here we demonstrate that this effect is responsible for the 2PA spectral shapes of many fluorescent dyes including rhodamines, ATTO dyes, fluorescein, oxazines, acridines, pyronines, resorufin, and thionine. By measuring the two-photon polarization ratio as a function of excitation wavelength in these dyes, we were able to separate the transitions with Deltamu perpendicular to the long molecular axis (“FC”-type) and parallel to it (“HT”-type). We have found the previously undetected “HT-ghost” transitions under the pure electronic envelope. These are the 0-0 transitions of the "HT" progression build on the BLA frequency that are non-vanishing if the corresponding Huang-Rhys factor is not zero.
Conference Presentation
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Mikhail Drobizhev and Rosana S. Molina "New quantum mechanical effect, resembling Herzberg-Teller coupling, explains the structure of the two-photon absorption spectra of dyes and fluorescent proteins", Proc. SPIE PC12863, Quantum Effects and Measurement Techniques in Biology and Biophotonics, PC1286309 (13 March 2024); https://doi.org/10.1117/12.3001942
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KEYWORDS
Dyes

Fluorescent proteins

Absorption spectrum

Vibration

Absorption

Chromophores

Modulation

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