Nonlinear saturation spectroscopy of the degenerate electron gas in spherical metallic particles

Classical Theory of Optical Nonlinearity in Conducting Nanoparticles

“…Previously, the above two terms have been used interchangeably, and it is accepted that the small-size effects are quantum mechanical in origin. Thus, they can be understood by considering discrete electron states in a nanoparticle [4,5] or reduction of interband screening and electron spillover near the nanoparticle surface [6,7]. In this Letter, we demonstrate that there is an additional, purely classical mechanism that leads to finite-size effects and, in particular, to nonlinearity of the electromagnetic response of conducting nanoparticles.…”

“…[4,5] from first principles. A conducting nanosphere was modeled as a degenerate electron gas placed in an infinitely high confining potential and subjected to a timeharmonic external electric field.…”

“…Thus, for example, in Ref. [5], a Hamiltonian was used with the interaction term V er E where E fE ext , E ext being the external field and f 1 ÿ 1 =3 ÿ1 the Lorentz factor. In other words, it was assumed that the electrons move in an electric field that is obtained from the solution to the Laplace equation, which does not account for finite-size effects.…”

Gold nanoparticle assemblies: interplay between thermal effects and optical response

“…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.…”

Quantum theory of the electromagnetic response of metal nanofilms

“…Although the model is mathematically tractable, it yields an expression for the third-order nonlinear polarizability, which involves an eight-fold series. This expression can be evaluated only approximately 12 . Recently, we have reduced analytically this expression (without resorting to any additional approximations) to a five-fold series, which is amenable to direct numerical evaluation 14 .…”