Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Modeling of Photochemical Reactions in a Focused Laser Beam



Fern Y. Hunt, Adolfas Gaigalas, Lili Wang


This paper presents a mathematical model of photodegradation of fluorophores passing through a laser beam. The beam is focused on the sample and thus the power distribution of incident light is strongly dependent on spatial location while the fluorophores are subject to a convective fluid flow. Experimentally accessible equations describing the time evolution of the fluorescent response over the entire region are derived. Mathematical justification for them is based on a multiple time scale analysis of the kinetics and approximations based on the amplitude of oscillatory component of the laser beam. The resulting equations can be used to interpret frequency domain measurements using traditional impedance concepts.
Journal of Research (NIST JRES) -


flowing solution, frequency domain, mathematical modeling, modulated laser illumination, photodegradation, singular perturbation technique


Hunt, F. , Gaigalas, A. and Wang, L. (2007), Modeling of Photochemical Reactions in a Focused Laser Beam, Journal of Research (NIST JRES), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed April 21, 2024)
Created June 30, 2007, Updated October 12, 2021