Time-resolved electron diffraction with atomic-scale spatial and temporal resolution was used to unravel the transformation pathway in the photoinduced structural phase transition of vanadium dioxide. Results from bulk crystals and single-crystalline thin-films reveal a common, stepwise mechanism: First, there is a femtosecond V-V bond dilation within 300 fs, second, an intracell adjustment in picoseconds and, third, a nanoscale shear motion within tens of picoseconds. Experiments at different ambient temperatures and pump laser fluences reveal a temperature-dependent excitation threshold required to trigger the transitional reaction path of the atomic motions.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4902825 | PMC |
http://dx.doi.org/10.1063/1.4953370 | DOI Listing |
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