Pump-probe spectroscopy of ultrafast structural relaxation of electronically excited rare gas heteroclusters

Abstract

Abstract We advance an approach for the study of multistate dynamics of low Rydberg excitations in XeAr N /Xe*( 3 P 1 )Ar N /Xe + Ar N clusters on the time scale of nuclear motion, as explored by pump-probe neutral-to excited-to positive ion (NEEXPO) femtosecond spectroscopy. The dynamics of the Xe*Ar N ( N =54) cluster induced by charge expansion inferred from the calculation of NEEXPO signals at different probe energies, manifests the lifetime τ 1 ≃100 fs for the initial formation of the ‘bubble’, an intracluster vibrational energy redistribution (IVR) lifetime τ I/e ≃5.0 ps and an IVR completion time τ c ≃8–10 ps, which corresponds to the bubble equilibration.