Heat dissipation for Au particles in aqueous solution: Relaxation time versus size
Heat dissipation for Au particles in aqueous solution: Relaxation time versus size
复制标题
DOI：
10.1021/jp020581
复制
发表时间：
2002-07-18
影响因子：
3.3
通讯作者：
Hartland, GV
中科院分区：
文献类型：
--
作者：
Hu, M;Hartland, GV
用泵浦-探测光谱法研究了Au纳米粒子向周围环境的能量耗散率。这些实验是对悬浮在水溶液中的颗粒进行的，其平均尺寸为直径4至50 nm。结果表明，能量弛豫是一个非常非指数的过程。拟合，数据到一个拉伸指数函数产生的特征时间尺度的松弛，从约。对于所检查的最小颗粒（类似于4 nm直径）为10 ps，对于50 nm直径的颗粒几乎为400 ps。弛豫时间与半径的平方成正比，但不依赖于初始温度。颗粒（即，泵浦激光功率）。对于非常小的粒子，能量耗散的时间尺度与电子-声子耦合的时间尺度相当，这意味着在电子和声子达到粒子内的热平衡之前发生显著的能量损失。
The rate of energy dissipation from Au nanoparticles to their surroundings has been examined by pump-probe spectroscopy. These experiments were performed for particles suspended in, aqueous solution, with average sizes ranging from 4 to 50 nm in diameter. The results show that energy relaxation is a very nonexponential process. Fitting, the data to-a stretched exponential function yields a characteristic time scale for relaxation that varies from ca. 10 ps for the smallest particles examined (similar to4 nm diameter) to almost 400 ps for the 50 nm diameter particles. The relaxation times are proportional to the square of the radius, but do not depend on the initial temperature of. the particles (i.e., the pump laser power). For very small particles, the time scale for energy dissipation is comparable to the time scale for electron-phonon coupling, which implies that significant energy loss occurs before the electrons and phonons reach thermal equilibrium within the particle.