Chemical Interface Damping Depends on Electrons Reaching the Surface

Abstract

Metallic nanoparticles show extraordinary strong light absorption near their plasmon resonance, orders of magnitude larger compared to nonmetallic nanoparticles. This "antenna" effect has recently been exploited to transfer electrons into empty states of an attached material, for example to create electric currents in photovoltaic devices or to induce chemical reactions. It is generally assumed that plasmons decay into hot electrons, which then transfer to the attached material. Ultrafast electron-electron scattering reduces the lifetime of hot electrons drastically in metals and therefore strongly limits the efficiency of plasmon induced hot electron transfer. However, recent work has revived the concept of plasmons decaying directly into an interfacial charge transfer state, thus avoiding the intermediate creation of hot electrons. This direct decay mechanism has mostly been neglected, and has been termed chemical interface damping (CID). CID manifests itself as an additional damping contribution to the homogeneous plasmon line width. In this study, we investigate the size dependence of CID by following the plasmon line width of gold nanorods during the adsorption process of thiols on the gold surface with single particle spectroscopy. We show that CID scales inversely with the effective path length of electrons, i.e., the average distance of electrons to the surface. Moreover, we compare the contribution of CID to other competing plasmon decay channels and predict that CID becomes the dominating plasmon energy decay mechanism for very small gold nanorods.

Insight into plasmonic hot-electron transfer and plasmon molecular drive: new dimensions in energy conversion and nanofabrication

“…[6][7][8] Interestingly, as a mechanism of electron transfer from plasmonic metals to semiconductors alternative to hot-electron transfer, chemical interface dumping, in which plasmons decay through a direct electron-separation channel at the interface, has been postulated. [9][10][11] A decade ago, we realized the potential of Au NPs to act as electron donors to TiO 2 NPs when in close contact. Hence, Au NPs can be viewed as photosensitizers instead of commonly employed dyes in dye-sensitized solar cells.…”

Effect of Linear Chain Lengths of 1‐Alkanethiols on Plasmon Damping of Single Gold Bipyramids with Sharp Tips

“…4,5 So far, ultrafast spectroscopy techniques have been used to investigate the relaxation pathway with the smallest time scale. [8][9][10][11] For instance, Foerster et al investigated the size dependence in a homogeneous LSPR linewidth broadening while varying the chemical environment of a single AuNR. Fortunately, measurements of the homogeneous linewidth of single nanoparticles provide an unprecedented way to overcome the time scale limitation.…”

Single‐Particle Study: Chemical Effect on Surface Plasmon Damping in Two‐Dimensional Gold Nanoprisms

“…As shown in Figure 2(b), thiol molecules in ethanol begin to bind to the AuNP surface through a strong Au S interaction. 21,23 Thus far, the CID effect on gold nanoparticles has been studied using thiol molecules because the thiol group ( SH) has a strong binding affinity for gold. 21,23 Thus far, the CID effect on gold nanoparticles has been studied using thiol molecules because the thiol group ( SH) has a strong binding affinity for gold.…”

“…8,9 Recently, two-dimensional (2D) gold nanoparticles, such as triangular gold nanoprisms (AuNPs), have attracted considerable interest because of their large surface to volume ratio, sharp corners and edges, which can enhance the electric field significantly. 21,22 Considerable effort has been made to characterize the effect of chemical adsorption on plasmon damping in 1D gold nanoparticles at the single-particle level, 21,23-25 but our understanding of the CID effect of 2D AuNPs with large surface to volume ratio is unclear. For instance, in the visible and near-infrared (IR) regions, 2D AuNPs with large surface to volume ratio present two characteristic dipole and quadrupole resonance modes.…”

“…For instance, typical quadrupole and dipole resonance modes are not observed clearly for thick AuNPs. 21,22 Considerable effort has been made to characterize the effect of chemical adsorption on plasmon damping in 1D gold nanoparticles at the single-particle level, 21,23-25 but our understanding of the CID effect of 2D AuNPs with large surface to volume ratio is unclear. [14][15][16] Furthermore, the dipole resonance wavelength is also shifted toward a longer wavelength when the thickness is decreased at a constant edge length.…”