Optical wavelength dependence of photoacoustic signal of gold nanofluid

Marco Gandolfi; Francesco Banfi; Christ Glorieux

doi:10.1016/j.pacs.2020.100199

Optical wavelength dependence of photoacoustic signal of gold nanofluid

Photoacoustics. 2020 Aug 12:20:100199. doi: 10.1016/j.pacs.2020.100199. eCollection 2020 Dec.

Authors

Marco Gandolfi^{1

2

3

4

5}, Francesco Banfi^{5

6}, Christ Glorieux³

Affiliations

¹ CNR-INO, Via Branze 45, 25123 Brescia, Italy.
² Department of Information Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy.
³ Laboratory of Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium.
⁴ Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, Via Musei 41, 25121 Brescia, Italy.
⁵ Interdisciplinary Laboratories for Advanced Materials Physics (I-LAMP), Via Musei 41, 25121 Brescia, Italy.
⁶ FemtoNanoOptics group, Université de Lyon, CNRS, Université Claude Bernard Lyon 1, Institut Lumière Matière, F-69622 Villeurbanne, France.

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