Elsevier

Photoacoustics

Volume 20, December 2020, 100199
Photoacoustics

Research article
Optical wavelength dependence of photoacoustic signal of gold nanofluid

https://doi.org/10.1016/j.pacs.2020.100199Get rights and content
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Highlights

  • Modelling of the photoacoustic effect of gold nanospheres dispersed in water and illuminated with ns laser pulses.

  • Laser wavelength dependence of the photoacoustic signal.

  • Comparison between the photoacoustic signal and the effective medium absorption coefficient.

  • Non-linearity of photoacoustic signal due to temperature dependence of thermal expansion coefficient.

  • Effect of nanosphere size and thermal boundary conductance on the photoacoustic signal magnitude and time evolution.

Abstract

We investigate the optical wavelength dependence of the photoacoustic (PA) signal, detected with bandwidth (BW) in the MHz range, of gold nanospheres (NSs) immersed in water upon illumination with ns laser pulses. We compare the wavelength dependence of the PA signal (within the MHz BW) with the one of the optical absorption coefficient as determined from optical transmission measurements. Thermal boundary conductance (TBC) at the gold-water interface is taken into account, as well as the temperature dependence of the thermal expansion coefficient of water. The effects of NS size and laser pulse duration on the PA signal are also explored. The PA signal is investigated with an opto-thermo-acoustic model considering light absorption in gold NS and in a surrounding water shell.

Keywords

Photoacoustic effect
Heat transfer
Absorption coefficient
Non-linearity
Kapitza resistance
Nanoparticles
Surface plasmon resonance

Cited by (0)

Marco Gandolfi obtained his MSc degree in Physics at Università Cattolica del Sacro Cuore (Italy) in 2014. Then he participated in a joint PhD project between KU Leuven (Belgium) and Università Cattolica del Sacro Cuore. He got his PhD in Physics in 2019. He currently works as a postdoctoral researcher at the National Institute of Optics (CNR-INO), in Italy. His interests cover the modelling of optics, thermics, mechanics and acoustics at the nanoscale.

Francesco Banfi earned his Ph.D. degree in physics from Università degli Studi of Pavia, Italy, in 2004. He is professor of physics at Université Claude Bernard Lyon 1 where he works at the Institute Lumière Matière. His scientific interests are in the field of ultrafast energy transients at the nanoscale. In the past years, his main contributions have been in the field of nano-scale mechanics and nano-scale heat transfer investigated by ultrafast optical techniques.

Christ Glorieux obtained his PhD degree in 1994 on the topic “Depth profiling of inhomogeneous materials and study of the critical behaviour of gadolinium by photoacoustic and related techniques,” from KU Leuven. Now he is an Associate Professor at the Laboratory of Soft Matter and Biophysics, KU Leuven. His research interests include photothermal applications, adiabatic scanning calorimetry and laser ultrasonics for the fundamental study of the thermophysical properties of complex soft and biological matter, the development of measurement techniques for characterization and depth profiling of thin (sub-micron) layered structures, non-destructive evaluation, physical acoustics, room acoustics, building acoustics and environmental acoustics. In March 2020, 257 articles (co-)authored by him were listed on Web of Science.