Local heating of water by high-intensity laser radiation

Abstract

Laser spectroscopy methods are being broadly used in various fields of science and technology nowadays. However, the interaction of laser radiation with matter can lead to the local heating of the medium. This effect is particularly important when probing the medium with high-intensity radiation. Local heating of water and aqueous media by intense laser radiation is of considerable interest within the context of biomedical applications.
Measuring the local temperature is a challenging task. Contact measurements cannot provide sufficient spatial resolution, while the commonly used infrared thermometry method may be used to determine the surface temperature of the sample only, making it improper for the set purpose. Raman scattering spectroscopy (RSS) has been successfully used for remote temperature measurement. Due to the fact that the shape of the water Raman band is highly sensitive to the temperature variation, this method is particularly effective for aqueous media.
This paper presents the results of a study on the local heating of water by high-intensity pulsed nanosecond laser radiation at the wavelengths of 532 and 1064 nm. The high sensitivity of the water Raman band shape to the temperature variation was used to determine the local temperature of the medium.
It was found that intense nanosecond laser radiation at the wavelength of 532 nm causes substantial local heating of water, even though water is optically transparent in this spectral range. However, probing water at the wavelength of 1064 nm does not result in significant heating. The results may be explained by the local heating of water due to multiphoton absorption.
This research was funded by the Russian Science Foundation grant #25-22-00411, https://rscf.ru/project/25-22-00411/.

Speaker

Petrov Ivan Sergeevych
Lomonosov Moscow State University
Russia

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