原子运动的电子加速和斯木斯的混乱
Germán Sciaini1, Maher Harb, Sergei G Kruglik
1Institute for Optical Sciences and Departments of Chemistry and Physics, University of Toronto, 80 St George Street, Toronto, Ontario M5S 3H6, Canada.
Nature
|March 6, 2009
概括
超快的电子衍射揭示了激光诱导的融在斯木发生在190 femtoseconds. 这种快速的固态到液态相位过渡是由电网沿线原子运动的电子加速驱动的.
科学领域:
- 凝聚物质物理学 凝聚物质物理学
- 材料科学 材料科学 材料科学
- 超快速光谱法 超快速光谱法
背景情况:
- 超高时间分辨率的X射线和电子衍射使激光诱导的固体结构变化能够在原子水平上绘制图.
- 之前对和半导体的研究表明,基于材料特性和激发,不同的融机制 (热与非热) 是不同的.
- 像珠这样的皮尔尔斯扭曲系统表现出独特的晶格动态,但它们的激光诱导的化反应仍未得到研究.
研究的目的:
- 为了研究在激光诱导化过程中使用秒电子衍射的晶石的结构动力学.
- 为了确定在强光激发下在斯木中相变的时间尺度和机制.
- 探索激发强度对斯木融动态的影响.
主要方法:
- 五秒电子衍射被用来探测晶体斯木的结构变化.
- 用不同的激光激发强度来诱导融化.
- 原子配置和格子动力学被以5秒分辨率分析.
主要成果:
- 观察到,在高激发强度下,激光诱导的石融化在190 femtosecond内发生.
- 发现融的动态很大程度上取决于激发强度.
- 融化发生在不被扰乱的A(1g) 格子模式的半个周期内,表明过渡非常快.
结论:
- 石的快速融化归因于激光诱导的格子的潜在能量表面的修改.
- 原子在纵向格子方向的强加速度和与不稳定的横向模式的合促进了快速的相位过渡.
- 石中的原子运动可以通过电子加速,使在次振动时间尺度上实现固态到液态相位过渡.
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