Kosc T Z, Kozlov A A, Papernov S, Kafka K R P, Marshall K L, Demos S G
Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, NY, 14623-1299, USA.
Sci Rep. 2019 Nov 11;9(1):16435. doi: 10.1038/s41598-019-52305-3.
We investigate the damage resistance of saturated and unsaturated liquid crystals (LC's) under a wide range of laser excitation conditions, including 1053-nm pulse durations between 600 fs and 1.5 ns and nanosecond pulse excitation at 351 nm and 532 nm. This study explores the relationship between the LC's resistance to laser-induced breakdown (damage) and the electronic structure (π-electron delocalization) of the constituent molecules. The laser-induced damage threshold at all wavelengths and pulse durations was consistently higher in saturated materials than in their unsaturated counterparts. The wavelength's dependence in the results suggests that the energy coupling process that leads to laser-induced breakdown is governed by the energy separation between the ground state and the first and second excited states, while the pulse duration's dependence in the results reveals the important role of electron relaxation between the excited states. A qualitative description was developed to interpret the experimental observations.
我们研究了饱和与不饱和液晶在广泛的激光激发条件下的抗损伤能力，这些条件包括1053纳米波长、脉冲持续时间在600飞秒至1.5纳秒之间，以及351纳米和532纳米波长的纳秒脉冲激发。本研究探讨了液晶对激光诱导击穿（损伤）的抗性与构成分子的电子结构（π电子离域）之间的关系。在所有波长和脉冲持续时间下，饱和材料的激光诱导损伤阈值始终高于其不饱和对应物。结果中波长的依赖性表明，导致激光诱导击穿的能量耦合过程受基态与第一和第二激发态之间的能量分离控制，而结果中脉冲持续时间的依赖性揭示了激发态之间电子弛豫的重要作用。我们开发了一种定性描述来解释实验观察结果。
