Mechanism of coherent acoustic phonon generation under nonequilibrium conditions
Mechanism of coherent acoustic phonon generation under nonequilibrium conditions
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DOI：
10.1103/physrevb.72.100301
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发表时间：
2005-09-01
影响因子：
3.7
通讯作者：
Cao, J
中科院分区：
文献类型：
--
作者：
Park, H;Wang, X;Cao, J
利用飞秒电子衍射技术研究了单原子铝薄膜中超快光激发产生的相干声学声子的动力学行为。相关的相干和热晶格运动同时测量亚毫埃空间分辨率在真实的时间。我们在这里表明，声子动力学可以很好地拟合与一个经典的谐振子模型使用的驱动力，其中包括电子和晶格的贡献。特别是，热自由电子的压力显着有助于在非平衡条件下，当电子和声子不热化驱动的相干声学声子。
We have investigated the dynamics of coherent acoustic phonons generated with ultrafast optical excitation in monoatomic Al films using femtosecond electron diffraction. Associated coherent and thermal lattice motions were measured simultaneously with sub milli-angstrom spatial resolution in real time. We show here that the phonon dynamics can be well fitted with a classical harmonic oscillator model using a driving force which includes both electronic and lattice contributions. In particular, the pressure of hot free electrons contributes significantly in driving the coherent acoustic phonons under nonequilibrium conditions when electrons and phonons are not thermalized.