Simulations and Experimental Study of Individual Au Nanoparticle Using Photothermal Heterodyne Imaging (PHI)

Photothermal heterodyne imaging (PHI), a new far-field microscopy, has become a major method for nanoparticles imaging. In this article, we studied the influences of laser parameters on PHI amplitude signals of individual gold nanoparticle (Au NP) by the finite element method (FEM) simulations and imaging experiments. Furthermore, a series of colocalization analyses were carried out with the PHI and the scanning electron microscopy (SEM). Individual Au NP with the diameters of 100 and 60 nm and nanoclusters were imaged by PHI with the backward configuration. The results show that PHI images could realize the imaging of individual 100- and 60-nm diameter Au NPs. Moreover, the size of nanoparticle determined by PHI phase images were in good agreement with the SEM results. In addition, we show that the PHI amplitude signal increases as the number of Au NP increases.