Details

Autor(en) / Beteiligte

• Baum, Peter
• Yang, Ding-Shyue
• Zewail, Ahmed H

Titel

4D Visualization of Transitional Structures in Phase Transformations by Electron Diffraction

Ist Teil von

• Science (American Association for the Advancement of Science), 2007-11, Vol.318 (5851), p.788-792

Ort / Verlag

Washington, DC: American Association for the Advancement of Science

Erscheinungsjahr

2007

Quelle

American Association for the Advancement of Science

Beschreibungen/Notizen

• Complex systems in condensed phases involve a multidimensional energy landscape, and knowledge of transitional structures and separation of time scales for atomic movements is critical to understanding their dynamical behavior. Here, we report, using four-dimensional (4D) femtosecond electron diffraction, the visualization of transitional structures from the initial monoclinic to the final tetragonal phase in crystalline vanadium dioxide; the change was initiated by a near-infrared excitation. By revealing the spatiotemporal behavior from all observed Bragg diffractions in 3D, the femtosecond primary vanadium-vanadium bond dilation, the displacements of atoms in picoseconds, and the sound wave shear motion on hundreds of picoseconds were resolved, elucidating the nature of the structural pathways and the nonconcerted mechanism of the transformation.