Pulse heating of water at the surface of gold nanoparticles: Femtosecond laser spectroscopy of energy relaxation of aqueous colloid of plasmonic nanoparticles under strong excitation conditions

The dynamics of differential absorption spectra of gold nanoparticles has been studied by femtosecond laser spectroscopy over a wide range of excitation energy density. The position of the plasmon resonance peak strongly depends on the dielectric properties of the medium, thereby allowing the use of plasmonic nanoparticles as an optical probe. It has been shown that femtosecond laser spectroscopy techniques, involving analysis of differential absorption spectra of gold nanoparticles in aqueous colloid nanolayer, make it possible to characterize the state of a water nanolayer surrounding the nanoparticle. In particular, at a high excitation energy density, the plasmon resonance absorption band exhibits spectral—kinetic features that suggest vaporization in the nanolayer around the gold particle.