Contributions from radiation damping and surface scattering to the linewidth of the longitudinal plasmon band of gold nanorods: a single particle study

Abstract

The scattering spectra of single gold nanorods with aspect ratios between 2 and 4 have been examined by dark field microscopy. The results show that the longitudinal plasmon resonance (electron oscillation along the long axis of the rod) broadens as the width of the rods decreases from 14 to 8 nm. This is attributed to electron surface scattering. Analysis of the data using gamma = gamma(bulk) + Anu(F)/L(eff), where L(eff) is the effective path length of the electrons and nu(F) is the Fermi velocity, allows us to determine a value for the surface scattering parameter of A = 0.3. Larger rods with widths of 19 and 30 nm were also examined. These samples also show spectral broadening, which is attributed to radiation damping. The relative strengths of the surface scattering and radiation damping effects are in excellent agreement with recent work on spherical gold nanoparticles by Sönnichsen et al., Phys. Rev. Lett., 2002, 88, 077402; and by Berciaud et al., Nano Lett., 2005, 5, 515.

Dark-field microscopy studies of single metal nanoparticles: understanding the factors that influence the linewidth of the localized surface plasmon resonance

“…31,34 As the size of the particles increases, coupling of the LSPR oscillation to the radiation field can become an important energy loss mechanism. 20,22,[32][33][34]46 This effect is known as radiation damping, and is not included in the above analysis. For spherical particles, radiation damping can be accounted for by using the full Mie theory expression to calculate the scattering cross-sections.…”

“…33,34,46 For the nanorods, electron-surface scattering is the dominant effect for narrow rods (widths < 10 nm), and radiation damping dominates for thick rods (widths > 20 nm). 33 Rods with "in between" thicknesses have narrow resonances, which are essentially free from either radiation damping or electron-surface scattering effects.…”

Landau damping of surface plasmons in metal nanostructures

“…Surface-assisted plasmon decay (Landau damping) has been extensively studied experimentally [33][34][35][36][37][38][39][40][41][42][43] and theoretically [44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59] since the pioneering paper by Kawabata and Kubo [44], who have shown that, for a spherical particle of radius a, the surface scattering rate is γ sp = 3v F /4a, where v F is the electron Fermi velocity. In subsequent quantum-mechanical studies carried within random phase approximation (RPA) [45][46][47][48][49][50][51] and timedependent local density approximation (TDLDA) [52][53][54][55][56][57][58][59] approaches, a more complicated picture has emerged involving the role of confining potential and nonlocal effects.…”

Determination of Morphological Parameters of Supported Gold Nanoparticles: Comparison of AFM Combined with Optical Spectroscopy and Theoretical Modeling versus TEM

“…Different techniques are employed to characterize the particle morphology [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39].…”

“…One direct and powerful technique is transition electron microscopy (TEM) [15,[28][29][30][31][32][33][34][35][36][37]40], but TEM suffers from the fact that sample preparation for three-dimensional TEM investigations is rather complicated and cannot be easily accomplished in situ. In addition, obtaining sufficient statistical data from TEM measurements is extremely time consuming.…”