Sie befinden Sich nicht im Netzwerk der Universität Paderborn. Der Zugriff auf elektronische Ressourcen ist gegebenenfalls nur via VPN oder Shibboleth (DFN-AAI) möglich. mehr Informationen...
Coherent Atomic Motions in a Nanostructure Studied by Femtosecond X-ray Diffraction
Ist Teil von
Science (American Association for the Advancement of Science), 2004-12, Vol.306 (5702), p.1771-1773
Ort / Verlag
United States: American Association for the Advancement of Science
Erscheinungsjahr
2004
Link zum Volltext
Quelle
American Association for the Advancement of Science
Beschreibungen/Notizen
Reversible structural changes of a nanostructure were measured nondestructively with subpicometer spatial and subpicosecond temporal resolution via x-ray diffraction (XRD). The spatially periodic femtosecond excitation of a gallium arsenide/aluminum gallium arsenide superlattice results in coherent lattice motions with a 3.5-picosecond period, which was directly monitored by femtosecond x-ray pulses at a 1-kilohertz repetition rate. Small changes (ΔR/R = 0.01) of weak Bragg reflexes (R = 0.005) were detected. The phase and amplitude of the oscillatory XRD signal around a new equilibrium demonstrate that displacive excitation of the zone-folded acoustic phonons is the dominant mechanism for strong excitation.