Key words: laser ablation, plasmonic nanoparticles, supercritical fluid, supercritical carbon dioxide, Mie Scattering
The dynamics of submicron gold particle formation during laser ablation in supercritical and liquid CO2 have been investigated using time-resolved Mie scattering absorption spectroscopy. It was found that a high density of CO2, approximately 800 kg/m3, regardless of the phase state, leads to the formation of laser-induced medium fluctuations on time scales of 10 to 1000 microseconds, during which the defocusing of subsequent laser pulses may occur. Under conditions of reduced fluid density in the vicinity of the Widom region (P = 8.5 Мра, T = 310 K), it was demonstrated that nanoparticles can leave the interaction zone unhindered, as evidenced by the exponential increase in integral absorption. Data from the absorption spectra allowed for the observation of nanoparticle formation dynamics, with an average diameter of approximately 160 nm and log-normal size.
doi:10.34984/SCFTP.2024.19.4.007