Cancellation of photoinduced absorption in metal nanoparticle composites through a counterintuitive consequence of local field effects

Abstract

By applying the Maxwell Garnett model to gold nanoparticles in water we deduce a value of Im i (3) ϭ 1.1 ϫ 10 Ϫ7 esu for the imaginary part of the cubic susceptibility for gold corresponding to a Fermi smearing mechanism. We also demonstrate a sign reversal in the nonlinear absorption for gold particles in 1, 1Ј, 3, 3, 3Ј, 3Ј-hexamethylindotricarbocyanine iodide. Although the imaginary part of (3) is positive for each component by itself, remarkably the imaginary part of (3) is negative for the colloid as a whole. We show that the nonlinearity of the host must be considered and that the sign reversal in (3) is a result of the fact that at the surface plasmon resonance the local field factor has an imaginary component that arises from a phase shift between the applied field and the local field inside the particle.

Enhanced nonlinearities using plasmonic nanoantennas

“…At the plasmon resonance, multiphoton processes may be amplifi ed by the enhanced electric fi eld within or in proximity of metallic nanoparticles. For example, it has been observed that size-dependent third harmonic generation (THG) is feasible in gold nanoparticles [29,46,47] . It is interesting to note that THG is induced at the particle surface, with a nonlinear dipole proportional to the area of the sphere rather than to its volume [29] , due to the small skin depth of metals and the corresponding small fi eld penetration.…”

Gold nanoparticle assemblies: interplay between thermal effects and optical response

“…From Eq. (11) or (12) it is obvious that dielectric confinement induces a local field correction to the nonlinear response of metal nanoparticles, which has several significant consequences [44,56,57]. Since both f and (3) m χ are complex quantities, the medium third-order nonlinear response may present unexpected values.…”

“…58 59 After focusing on the effect of dielectric confinement on the third-order nonlinear optical response, let us glance at the intrinsic nanoparticle susceptibility. Surprisingly, very few theoretical works have been devoted to the value of (3) m χ in noble metal nanoparticles [57,58] after the pioneering studies of Flytzanis' group who identified and evaluated the different electronic contributions [47,48,56,59]. They first distinguished two pure nonlinear origins corresponding to intraband and interband transitions as in the linear case.…”

Cascading and local-field effects in non-linear optics revisited: A quantum-field picture based on exchange of photons

“…Local-field effects were included in off-resonant frequency domain susceptibilities to resolve discrepancies of the calculated absolute magnitude with experiment. [4][5][6][7] In the time domain, they were required when unexpected signals showed that the time ordering of short pulses is scrambled by molecules with long-lived polarization (slow dephasing). 8,9 Various other experimental observables that are altered by local-field effects, such as the transmission/reflection of a thin film 10 and the Rabi oscillations of a quantum dot 11 have been identified.…”