Direct electron density modulation of surface plasmons with a scanning electron microscope

Abstract

The optical properties of localized surface plasmon resonance (LSPR) were modulated by direct electron injection using scanning electron microscopy (SEM). The predictions of electromagnetic theory for LSPR on charged metal nanoparticles were experimentally verified using a novel microscopic system. Extinction spectra were obtained for gold nanostructures that were under intense electron irradiation using an SEM system equipped with an optical microscope. High-frequency shifts of LSPR were observed for a single gold nanosphere, nanodimer, and nanorod, and the amount of the shifts was explained with respect to their symmetry.

Plasmooptoelectronic tuning of optical properties and SERS response of ordered silver grating by free carrier generation

“…The absolute value of free carrier changes (10 26 ) constitutes approximately one percent of the total concentration of free carriers in silver (10 28 ). This result corresponds well with the results published for LSP case, 3,21,22 where the increasing of free carrier concentration by one percent leads to similar changes in the plasmon absorption peak. From the Table 1A is evident, that the calculated changes of free carries slightly increase with decreasing of grating amplitude but the observed differences are of the order of the errors introduced by the simplied model chosen for calculation.…”

“…21 Alternatively, metal NPs were charged by argon plasma or by electron beam. 22,23 Variation of the charging effect with NPs shape and size was observed as well. 24 Generally, the plasmon peak does not shi more than 1-10 nm and its intensity increases up to several percent in regard to the initial value.…”

“…A similar slight shi of absorption maximum position was theoretically and experimentally reported for the case of localized surface plasmon (LSP) resonance. [20][21][22][23][24] But unlike in the case of LSP, the reported shi of SPP is accompanied by signicant changes of absolute absorption coefficient at the SPP peak wavelength. Depending on the position of the transition area, SPP peak is located in the shorter or longer wavelength part of the spectrum and correspondingly its absolute value of absorption decreases or increases by cca 30%.…”

Tracking Sub-Nanometer Shift in the Scattering Centroid of Single Gold Nanorods during Electrochemical Charging

“…A typical example is the non-Faradaic electrochemical charging of gold nanorods (AuNRs). 17 As shown in a milestone work by Mulvaney and co-workers, 13,18 applying a negative potential to AuNRs was found to induce a blue shift of its plasmonic band. This observation happens because the injected electrons increased the electron density of AuNRs and altered its dielectric constant accordingly, an essential factor regulating the localized surface plasmon resonance (LSPR).…”

“…Although the full spectrum was not available, this approach offered very high temporal resolution. A typical example is the non-Faradaic electrochemical charging of gold nanorods (AuNRs) . As shown in a milestone work by Mulvaney and co-workers, , applying a negative potential to AuNRs was found to induce a blue shift of its plasmonic band.…”