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Nonexponential statistics of fluorescence photobleaching

Berglund, Andrew J. (2004) Nonexponential statistics of fluorescence photobleaching. Journal of Chemical Physics, 121 (7). pp. 2899-2903. ISSN 0021-9606. doi:10.1063/1.1773162.

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In this paper, I consider theoretical models of the decay via photobleaching of a sample of surface-immobilized fluorescent molecules excited by a spatially varying laser intensity profile. I show that, with mild restrictions on the photobleaching mechanism, the fluorescence decay measured in a nonuniform excitation profile is always nonexponential. Under the same conditions, the fluorescence decay can always be approximated by a discrete sum of exponentials. A particular example is given in which a homogeneous population of fluorophores with a single (intensity-dependent) photobleaching lifetime, when illuminated by a Gaussian laser, exhibits power law fluorescence decay at long times. These results indicate that the observation of multiple exponentials in single molecule or ensemble photobleaching lifetime measurements can arise solely as an artifact of a spatially varying laser profile and is not necessarily indicative of heterogeneity in molecular internal states, conformation, or local environment.

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Additional Information:Copyright © 2004 American Institute of Physics. Received 26 February 2004; accepted 25 May 2004. This work was performed in Hideo Mabuchi’s group, and the author gratefully acknowledges their support and technical advice. The author also thanks Kevin McHale for a careful reading of the manuscript. This work was supported by the Institute for Collaborative Biotechnologies through grant DAAD19-03-D-0004 from the U.S. ARO, and by the NSF under Grant Nos. EIA-0323542 and EIA-0113443. Any opinions, findings, and conclusions or recommendations expressed in this material were those of the author and do not necessarily reflect the views of either funding agency.
Subject Keywords:optical saturable absorption; fluorescence; radiative lifetimes; excited states
Issue or Number:7
Record Number:CaltechAUTHORS:BERjcp04
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1879
Deposited By: Tony Diaz
Deposited On:22 Feb 2006
Last Modified:08 Nov 2021 19:43

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