Computational characterization of plasma effects in ultrafast laser irradiation of spherical gold nanostructures for photothermal therapy. (8th February 2016)

• Record Type: Journal Article
• Authors: Hatef, Ali; Darvish, Behafarid; Burke, Adam; Dagallier, Adrien; Meunier, Michel
• Is Part Of: Journal of physics. Volume 49:Number 10(2016)
• Publication Date: 2016-02-08
• Subjects: spherical gold nanoparticle -- solid and core–shell nanoparticle -- energy deposition -- plasmon resonance -- plasma dynamics -- ultrashort pulsed laser -- photothermal therapy; Physics -- Periodicals; 530
• DOI: 10.1088/0022-3727/49/10/105401
• Languages: English
• ISSNs: 0022-3727

Abstract

Abstract: Ultrashort pulsed lasers can provide high peak intensity with low pulse fluence. This makes them an ideal choice in photothermal therapy and applications where damage to the surrounding material needs to be minimized. Depending on the peak intensity, the ultrashort pulsed laser's interaction with matter can lead to plasma formation through nonlinear effects such as multiphoton and impact electron excitation. The capability of the spherical gold nanoparticles, as the most employed nanoparticle so far for photothermal therapy, to enhance and strongly localize the incident laser field leads to plasma formation around the particles at even lower pulse fluences. Under certain circumstances, during the pulse duration, this plasma can absorb more energy than the nanoparticle itself. Consequently, the absorbed energy by the generated plasma can act as an energy source for different phenomena such as the evolution of the temperature distribution, thermoelastic stress generation, and stress-induced bubble formation. In this paper, we study the plasma-mediated interaction of a 45 fs pulsed laser with two types of spherical gold nanoparticles in water: solid nanoparticle and core–shell (silica–gold) nanoparticle. We use a numerical framework based on the finite element method (FEM) to compare energy deposition profiles in these nanoparticles and in their surrounding plasma, by focusing on the impact of the nanoparticle size and the laser fluence. Our calculations show that the maximum energy deposition in plasma occurs in core–shell nanoparticles with a diameter of 130 nm and the ratio of core to shell radius of 0.8 and in solid nanoparticles with a diameter of 170 nm.