Time-resolved analysis of strong-field induced plasmon oscillations in metal clusters by spectral interferometry with few-cycle laser fields

摘要

We propose a scheme for ultrafast real-time imaging of laser-inducedcollective electron oscillations (Mie plasmons) in gas phase metal clusters byinterferometrically stable scanning of two intense few-cycle optical laserpulses. The feasibility of our nonlinear spectral interferometry method withexperimentally accessible observables is tested in a theoretical case study onsimple-metal clusters (Na$_{147}$). The results show that the plasmon periodand lifetime as well as the phase and relative amplitude of the collectiveelectron motion can be extracted with sub-fs resolution. The access tononlinear response effects, as the demonstrated increase of the plasmonlifetime with laser intensity due to ionization-induced contraction of theelectron cloud, opens up vast opportunities for interrogating ultrafastmany-particle dynamics in nanosystems under strong laser fields withunprecedented resolution.