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Ultrafast Carrier and Lattice Dynamics in Plasmonic Nanocrystalline Copper Sulfide Films
Laser & Photonics Reviews ( IF 9.8 ) Pub Date : 2021-01-21 , DOI: 10.1002/lpor.202000346
Anton Yu Bykov 1 , Amaresh Shukla 1 , Mark van Schilfgaarde 1, 2 , Mark A Green 1 , Anatoly V Zayats 1
Affiliation  

Excited carrier dynamics in plasmonic nanostructures determines many important optical properties such as nonlinear optical response and photocatalytic activity. Here it is shown that mesoscopic plasmonic covellite nanocrystals with low free‐carrier concentration exhibit a much faster carrier relaxation than in traditional plasmonic materials. A nonequilibrium hot‐carrier population thermalizes within first 20 fs after photoexcitation. A decreased thermalization time in nanocrystals compared to a bulk covellite is consistent with the reduced Coulomb screening in ultrathin films. The subsequent relaxation of thermalized, equilibrium electron gas is faster than in traditional plasmonic metals due to the lower carrier concentration and agrees well with that in a bulk covellite showing no evidence of quantum confinement or hot‐hole trapping at the surface states. The excitation of coherent optical phonon modes in a covellite is also demonstrated, revealing coherent lattice dynamics in plasmonic materials, which until now was mainly limited to dielectrics, semiconductors, and semimetals. These findings show advantages of this new mesoscopic plasmonic material for active control of optical processes.

中文翻译:

等离激元纳米晶硫化铜薄膜中的超快载流子和晶格动力学

等离子体纳米结构中的激发载流子动力学决定了许多重要的光学性质,例如非线性光学响应和光催化活性。这里表明,具有低自由载流子浓度的介观等离子体蓝蓝纳米晶体表现出比传统等离子体材料更快的载流子弛豫。非平衡热载流子群在光激发后的前 20 fs 内热化。与块状钴蓝相比,纳米晶体的热化时间缩短,这与超薄膜中库仑屏蔽的减少是一致的。由于载流子浓度较低,热化平衡电子气的随后弛豫速度比传统等离子体金属更快,并且与块体钴蓝中的弛豫非常吻合,没有证据表明表面态存在量子限制或热空穴俘获。还演示了蓝蓝中相干光学声子模式的激发,揭示了等离子体材料中的相干晶格动力学,迄今为止,等离子体材料主要限于电介质、半导体和半金属。这些发现显示了这种新型介观等离子体材料在主动控制光学过程方面的优势。
更新日期:2021-03-11
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