Ultrafast Dephasing of Single Nanoparticles Studied by Two-Pulse Second-Order Interferometry

Abstract

Two-pulse second-order interferometric autocorrelation responses of single Ag nanoparticles are reported. The surface plasmon-enhanced second harmonic generation interferogram for single Ag colloids shows significant broadening with respect to the laser pulse second-order autocorrelation. The interferometric autocorrelation response is described and analyzed with a density matrix formalism that incorporates (phenomenologically) the population and the polarization relaxation of the surface plasmon. The total dephasing time (T 2 ) of the surface plasmon in single Ag colloids is determined to be 10 fs. The present results are compared to previously reported values obtained from ensemble studies of Ag particles and from the line width of the absorption spectrum. Extension of the present ultrafast measurements, the first performed on single nanoparticles, to single molecules studies is discussed.

Metal‐nanoparticle plasmonics

“…The SHG signal from such particles was used in an autocorrelation configuration to directly measure the dephasing time of nanoparticle plasmons. This technique was later extended to the study of single nanoparticles [89]. Other measurements extended this technique by using third-harmonic generation (THG) instead, thereby allowing centrosymmetric particles to be studied [90].…”

Ultrafast resonant optical scattering from single gold nanorods: Large nonlinearities and plasmon saturation

“…By contrast, isolating single particles allows the quantitative measurement of inherent properties. 15,16,17 We report the first measurements of resonant nonlinearities of surface plasmons in single metal nanoparticles, specifically Au nanorods. 18,19 We measure a nonlinear scattering cross-section that is much larger than that obtained from ensembles of nanorods.…”

Photovoltage and Photocatalyzed Growth in Citrate-Stabilized Colloidal Silver Nanocrystals

“…The coherent plasmon dephases within femtoseconds, producing a hot electron gas. [1][2][3] After electronic thermalization, energy relaxation occurs by exciting lattice phonons within the particle in a matter of picoseconds.…”