Effect of Single Femtosecond Pulses on Gold Nanoparticles

Gold nanoparticles find a wide range of applications in optics and photonics; however, their detailed interaction with intense laser light is only partially understood. Previous works have studied the effect of intense pulse trains on gold nanoparticles at a wide range of illumination parameters and observed diverse optical and morphological changes. In this work we study, for the first time, the interaction between single femtosecond pulses and gold nanoparticles. Using transmission electron microcopy and optical spectroscopy, we have found that nanoparticles illuminated by 50 fs pulses with fluence of less than 0.15 J/cm2 per pulse (3 TW/cm2) undergo morphological changes that affect their extinction spectra. Experimentation with particles of different diameters show similar qualitative effects, which are more pronounced for larger particles. Pulses at different excitation wavelengths were found to induce different effects for resonance and off-resonance conditions. The presented results provide valuable experimental data on the complex pulse−particle interaction and would be helpful for better understanding of the physical processes that are involved.