Photoinduced Heat Generation Mechanism in Ag Nanoparticles Embedded in SiO_2 and β-In_2S_3 Matrix

摘要

In this work we probe the photothermal conversion properties of individual metal (Ag) nanoparticle, semiconductor (β-In_2S_3) microflowers, dielectric (SiO_2) nanostructures and Ag nanoparticles embedded in β-In_2S_3 and SiO_2 matrix. The heat generated from the Ag nanoparticles is much higher when embedded inside polymer encapsulated SíO_2 and β-In_2S_3 matrix than the individual nanoparticle assembly. The heat generation mechanism is shown to be an ultrafast process (picoseconds) when the Ag nanoparticles are embedded in a β-In_2S_3 complex, while for individual Ag nanoparticles and Ag: SiO_2 matrix the process is shown to be time delayed. The change is attributed to the resonant heat transfer mechanism. The measurements were carried out by illuminating the samples with pump beam of 445 nm. The refractive index gradient produced in the surrounding air due to thermal waves emanating from the sample is measured using a probe beam of wavelength 546 nm and a position sensitive quadrant cell detector.