Photothermal properties of gold nanoparticles

This paper describes our recent time-resolved spectroscopy studies of the properties of gold particles at high laser excitation levels. In these experiments, an intense pump laser pulse rapidly heats the particle, creating very high lattice temperatures - up to the melting point of bulk gold. These high temperatures can have dramatic effects on the particle and the surroundings. The lattice temperature created is determined by observing the coherently excited the vibrational modes of the particles. The periods of these modes depend on temperature, thus, they act as an internal thermometer. We have used these experiments to provide values for the threshold temperatures for explosive boiling of the solvent surrounding the particles, and laser induced structural transformations in non-spherical particles. The results of these experiments are relevant to the use of metal nanoparticles in photothermal therapy, where laser induced heating is used to selectively kill cells.