不同形态银纳米粒子的非线性光学特性

通过光诱导生长制备了三角形和圆盘形银纳米粒子, 并采用飞秒Z-scan技术考察了这2种形貌的银纳米粒子在800 nm光波长下的非线性光学特性. 在基态等离子漂白和自由载流子吸收等效应的作用下, 粒径为75 nm的三角形银纳米粒子的非线性透过率随激发光强的增加而呈现由饱和向反饱和非线性吸收过渡的现象; 粒径为35 nm的圆盘形银纳米粒子仅表现出反饱和吸收现象. 实验结果表明, 银纳米粒子非线性吸收过程受粒子形态调控.

Nonlinear Optical Properties of Silver Nanocrystals with Different Shapes

ilver nanocrystals with prism and disk shapes have been synthesized by the light-driven growth method in an aqueous solution.Nonlinear optical properties of these two samples were investigated by home-built femtosecond Z-scan system with 800 nm incident wavelength.The Ag nanoprisms with 75 nm size show 700 nm SPR peak and exhibit both negative and positive nonlinear absorption.The nonlinear absorption process is considered to be generated by ground-state plasmon bleaching,free-carrier absorption,and interband transitions.The Ag nanodisks with 35 nm size show 495 nm SPR peak.However,Ag nanodisks display only positive nonlinear absorption process.The different nonlinear absorption process is attributed to the morphology influence by the Ag nanocrystals.