Ultrafast Dynamics of Gold-Based Nanocomposite Materials†
Ultrafast Dynamics of Gold-Based Nanocomposite Materials†
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DOI：
10.1021/jp026885d
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发表时间：
2003-05
影响因子：
2.9
通讯作者：
J. Melinger;V. Kleiman;D. McMorrow;F. Gröhn;B. Bauer;E. Amis
中科院分区：
文献类型：
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作者：
J. Melinger;V. Kleiman;D. McMorrow;F. Gröhn;B. Bauer;E. Amis
比较了两种不同环境下小颗粒(平均直径为2.5~4.0 nm)Au纳米粒子的超快电子动力学。在一种情况下，水溶液中含有嵌入在聚酰胺胺(PAMAM)树枝状大分子中的金纳米颗粒(平均直径为2.5或4.0 nm)。在另一种情况下，将平均直径为3.6 nm的六硫醇钝化(HT)金纳米颗粒悬浮在二氯甲烷溶液中。利用飞秒双色泵浦−探测光谱对表面等离子体共振区Au纳米粒子的动力学行为进行了激发和探测。测量了作为激光激发通量(J/cm2)的函数的瞬时响应。对于金属−树枝状大分子纳米复合材料，其暂态响应为单指数衰减，其驰豫时间常数小于1.2ps，其主要原因是电子−声子耦合。弛豫时间标度对激发通量的依赖性很弱，但与Au的大小基本无关。
Ultrafast electron dynamics are compared for small (2.5- to 4.0-nm average diameter) Au nanoparticles in two different surrounding environments. In one case, an aqueous solution contains Au nanoparticles (with average diameters of either 2.5 or 4.0 nm) embedded inside polyamidoamine (PAMAM) dendrimers. In the other case, hexanethiol-passivated (HT) Au nanoparticles, with an average diameter of 3.6 nm, are suspended in dichloromethane solution. Femtosecond two-color pump−probe spectroscopy is used to excite and probe the dynamics of the Au nanoparticles in the region of the surface plasmon resonance. The transient response is measured as a function of laser excitation fluence (J/cm2). For the metal−dendrimer nanocomposites, the transient response consists of a single-exponential decay that relaxes with a time constant of less than 1.2 ps and is due mainly to electron−phonon coupling. The relaxation time scale shows a weak dependence on excitation fluence but is essentially independent of the size of the Au...