2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/26526We measure the transient absorption of single gold particles with a common-path interferometer. The prompt electronic part of the signal provides high-contrast images for diameters as small as 10 nm. Mechanical vibrations of single particles appear on a longer timescale (period of 16 ps for 50 nm diameter). They reveal the full heterogeneity of the ensemble, and the intrinsic damping of the vibration. We also observe a lower-frequency mode involving shear. Ultra-fast pump-probe spectroscopy of individual particles opens new insight into mechanical properties of nanometer-sized objects.4 pages, 4 figures and supplementary material (3 pages, 3 figures); submitted 18May05 to PRLOther Condensed Mattertext