Knappenberger Kenneth L, Schwartzberg Adam M, Dowgiallo Anne-Marie, Lowman Casey A
Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4901, USA.
J Am Chem Soc. 2009 Oct 7;131(39):13892-3. doi: 10.1021/ja903086g.
Electronic relaxation and interparticle electromagnetic coupling processes in hollow gold nanospheres (HGNs) and HGN aggregates are described. These plasmon-tunable HGNs exhibit an unexpected, but systematic, blue shift of the surface plasmon resonance spectral position when the particles are aggregated. Femtosecond transient absorption measurements and finite-difference time-domain (FDTD) calculations are used to demonstrate that this blue shift is the result of delocalization of the Fermi-gas over multiple particles, an effect not observed with solid spherical particles. The ultrafast electron-phonon coupling lifetimes for the thin-shelled HGNs increase upon aggregation, indicating significant enhancement in interparticle electromagnetic coupling. For instance, a 48-nm HGN with a shell thickness of 7 nm shows ultrafast electron-phonon coupling with a lifetime of 300 +/- 100 fs, and upon aggregation, this lifetime increases to 730 +/- 140 fs. The experimental data strongly suggest that confinement effects in HGNs allow for enhanced energy transport over nanometer distances and this effect can be applied to developing more efficient devices, including photovoltaics.
描述了中空金纳米球（HGNs）和HGN聚集体中的电子弛豫和粒子间电磁耦合过程。当这些等离子体可调谐的HGNs聚集时，其表面等离子体共振光谱位置会出现意想不到但却系统的蓝移。飞秒瞬态吸收测量和时域有限差分（FDTD）计算被用于证明这种蓝移是费米气体在多个粒子上离域的结果，这种效应在实心球形粒子中未被观察到。聚集时，薄壳HGNs的超快电子 - 声子耦合寿命增加，表明粒子间电磁耦合显著增强。例如，一个壳厚度为7 nm的48 - nm HGN显示出超快电子 - 声子耦合，寿命为300 +/- 100 fs，聚集后，该寿命增加到730 +/- 140 fs。实验数据有力地表明，HGNs中的限制效应允许在纳米距离上增强能量传输，并且这种效应可应用于开发更高效的器件，包括光伏器件。
