Direct and real-time probing of both coherent and thermal lattice motions
نویسندگان
چکیده
We report direct measurement of laser-induced ultrafast structural dynamics on the atomic time and length scales in a 20-nm Al film by taking real-time snapshots of transmission electron diffraction patterns. The damped single-mode breathing motion of the Al film along the surface normal was recorded as coherent and in-phase oscillations of all the Bragg peak positions, which had a period of 6.4 ps. The concurrent lattice heating with a time constant of 630 fs was measured by tracking the associated Bragg peak intensity attenuation. These results suggest a direct approach to identify the mechanisms of laser-induced ultrafast solid–liquid phase transition, as well as thermal or non-thermal melting, via probing the temporal evolution of their diffraction patterns. q 2005 Elsevier Ltd. All rights reserved. PACS: 78.47.+p; 45.80+5; 46.40.-f; 63.20.-e
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