Hafke B, Witte T, Janoschka D, Dreher P, Meyer Zu Heringdorf F-J, Horn-von Hoegen M
Department of Physics and CENIDE, University Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, Germany.
Struct Dyn. 2019 Aug 2;6(4):045101. doi: 10.1063/1.5111636. eCollection 2019 Jul.
Strong optical irradiation of indium atomic wires on a Si(111) surface causes the nonthermal structural transition from the (8 × 2) reconstructed ground state to an excited (4 × 1) state. The immediate recovery of the system to the ground state is hindered by an energy barrier for the collective motion of the indium atoms along the reaction coordinate from the (4 × 1) to the (8 × 2) state. This metastable, supercooled state can only recover through nucleation of the ground state at defects like adsorbates or step edges. Subsequently, a recovery front propagates with constant velocity across the surface and the (8 × 2) ground state is reinstated. In a combined femtosecond electron diffraction and photoelectron emission microscopy study, we determined-based on the step morphology-a velocity of this recovery front of ∼100 m/s.
对硅（111）表面的铟原子线进行强光照射会导致其从（8×2）重构基态到激发态（4×1）的非热结构转变。铟原子沿反应坐标从（4×1）态到（8×2）态的集体运动存在能垒，这阻碍了系统立即恢复到基态。这种亚稳态的过冷状态只能通过在吸附物或台阶边缘等缺陷处形成基态核来恢复。随后，恢复前沿以恒定速度在表面传播，（8×2）基态得以恢复。在一项结合飞秒电子衍射和光电子发射显微镜的研究中，我们根据台阶形态确定了这个恢复前沿的速度约为100米/秒。
