Molecular and Surface Physics, Faculty of Physics, Bielefeld University, Germany.
J Phys Condens Matter. 2011 Nov 2;23(43):435402. doi: 10.1088/0953-8984/23/43/435402. Epub 2011 Oct 13.
We report direct observations of the structural and electronic dynamics of the photoinduced insulator-metal transition in VO(2), by means of time-resolved photoemission spectroscopy. These observations provide new insights into the processes involved in this transition. Slightly above the threshold of the photoinduced phase transition, the different response times of the electrons and the lattice reveal the electronic nature of the band gap collapse. At high excitation densities, we find that the phase transition is induced nonthermally in an ultrashort time scale. Moreover, we identify different V 3p dynamics indicating the existence of different structural pathways. These results represent a clear demonstration of the potential of time-resolved core level photoelectron spectroscopy to study ultrafast dynamics in condensed matter.
我们通过时间分辨光发射谱直接观察到 VO(2)中光诱导绝缘-金属相变的结构和电子动力学。这些观察结果为这一相变过程提供了新的见解。在光诱导相变的阈值以上，电子和晶格的不同响应时间揭示了带隙坍塌的电子性质。在高激发密度下，我们发现相变在极短的时间尺度内非热诱导。此外，我们还发现了不同的 V 3p 动力学，表明存在不同的结构途径。这些结果清楚地证明了时间分辨芯能级光电子谱在研究凝聚态物质中超快动力学的潜力。
