We introduce an effect of metallization of dielectric nanofilms by strong, adiabatically varying electric fields. The metallization causes optical properties of a dielectric film to become similar to those of a plasmonic metal (strong absorption and negative permittivity at low optical frequencies). The is a quantum effect, which is exponentially size-dependent, occurring at fields on the order of 0.1 V/Å and pulse durations ranging from ∼ 1 fs to ∼ 10 ns for film thickness 3 − 10 nm. PACS numbers: 73.20.Mf 77.22.Jp 42.65.Re, 72.20.Ht Effects of strong electric fields on electron states in crystals have attracted a great deal of attention over many decades going back to Zener who predicted breakdown due to interband tunneling 1 . In insulators this requires electric fields on the order of atomic fields E ∼ 1 − 10 V/Å. Interest to strong-field condensed matter physics has recently greatly increased due to the availability of such strong electric fields in laser pulses of intensities I ∼ 10 13 − 10 15 W/cm 2 . Ultrashort laser pulses with a few optical oscillations2,3 open up a possibility to study ultrastrong field phenomena in solids during periods of time too short for the lattice ions to move significantly. Recent ab initio calculations 4 have reproduced the Zener breakdown in insulators induced by a laser pulse of intensity ∼ 10 15 W/cm 2 . Other strongfield phenomena that can be observable in crystals at a comparable field strength are the appearance of localized electron states, Wannier-Stark ladder in the energy spectrum 5,6 , and Bloch oscillations. 7 At orders of magnitude lower intensities, low-frequency optical fields cause a reduction of the band gap in semiconductors and insulators (Franz-Keldysh effect, FKE) 8,9 . The quantum confined FKE takes place in semiconductor quantum wells and is determined not by the field but by the total potential drop.10 It requires typical fields E ∼ 10 −3 V/Å.In this Letter we introduce an effect of metallization in insulator nanofilms, which is predicted to occur in applied electric fields E ∼ 0.1 V/Å. It is based on adiabatic electron transfer in space across the nanofilm. The minimum duration of the field pulse required for the adiabaticity exponentially depends on the crystal thickness varying from ∼ 1 fs for a 3 nm film to ∼ 10 ns for a 10 nm film thickness. This metallization effect manifests itself by a dramatic change in the optical properties of the system, which start to remind those of metals. In particular, plasmonic phenomena emerge.To demonstrate the metallization effect, we need to solve the one-electron Schrödinger equation for a periodic potential plus a uniform electric field very accurately. We will employ the widely used Kronig-Penney model for electrons in a film confined in the x direction by an infinite potential well. The corresponding potential energy (neglecting the electron-electron interaction) iswhere, and a is the lattice constant. Crystal thickness L is determined by the number of the lattice periods N in the x direction, L = N a. Thou...

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Here, for the first time we predict a giant surface-plasmon-induced drag-effect rectification (SPIDER), which exists under conditions of the extreme nanoplasmonic confinement. In nanowires, this giant SPIDER generates rectified THz potential differences up to 10 V and extremely strong electric fields up to approximately 10(5)-10(6) V/cm. The giant SPIDER is an ultrafast effect whose bandwidth for nanometric wires is approximately 20 THz. It opens up a new field of ultraintense THz nanooptics with wide potential applications in nanotechnology and nanoscience, including microelectronics, nanoplasmonics, and biomedicine.

We predict a dynamic metallization effect where an ultrafast (single-cycle) optical pulse with a ≲1 V/Å field causes plasmonic metal-like behavior of a dielectric film with a few-nm thickness. This manifests itself in plasmonic oscillations of polarization and a significant population of the conduction band evolving on a ~1 fs time scale. These phenomena are due to a combination of both adiabatic (reversible) and diabatic (for practical purposes irreversible) pathways.

Nanostructured plasmonic metal systems are known to enhance greatly variety of radiative and nonradiative optical processes, both linear and nonlinear, which are due to the interaction of an electron in a molecule or semiconductor with the enhanced local optical field of the surface plasmons. Among them are surface enhanced Raman scattering (SERS) 1,2,3,4,5,6 , surface plasmon enhanced fluorescence 5,7,8,9,10,11 , fluorescence quenching in the proximity of metal surfaces, 7,10,12 coherent anti-Stokes Raman scattering (CARS) 13 , surface enhanced hyper-Raman scattering (SEHRS) 14 , etc. Principally different are numerous many-body phenomena that are due to the Coulomb interaction between charged particles: carriers (electrons and holes) and ions. These include carrier-carrier or carrier-ion scattering, energy and momentum transfer (including the drag effect), thermal equilibration, exciton formation, impact ionization, Auger effects, 15 etc. It is not widely recognized that these and other many-body effects can also be modified and enhanced by the surface-plasmon local fields. A special but extremely important class of such many-body phenomena is constituted by chemical reactions at metal surfaces, including catalytic reactions. Here, we propose a general and powerful theory of the plasmonic enhancement of the many-body phenomena resulting in a closed expression for the surface plasmon-dressed Coulomb interaction. We illustrate this theory by computing this dressed interaction explicitly for an important example of metal-dielectric nanoshells, 16 which exhibits a reach resonant behavior in both the magnitude and phase. This interaction is used to describe the nanoplasmonic-enhanced Förster energy transfer between nanocrystal quantum dots in the proximity of a plasmonic nanoshell. This is of great interest for plasmonic-enhanced solar cells and light-emitting devices. 17 Catalysis at nanostructured metal surfaces, nonlocal carrier scattering, and surface-enhanced Raman scattering are discussed among other effects and applications where the nanoplasmonic renormalization of the Coulomb interaction may be of principal importance. PACS numbers: 78.67.-n, 71.45.Gm, 73.20.MfConsider a system of charged particles situated in the vicinity of a plasmonic metal nanosystem. For definiteness, we will assume that these particles are electrons, although they can also be holes or ions of the lattice. One of the examples of such systems is a semiconductor in the proximity of a nanostructured metal surface. When an electron undergoes a transition with some frequency ω, this transition is accompanied by local electric fields oscillating with the same frequency. These fields excite surface plasmon (SP) modes with the corresponding frequencies whose fields overlap in space with the transition fields. A property of these SP eigenmodes is that they can be delocalized over the entire nanostructure 18 . The local optical fields of the SPs can excite a resonant transition of another electron. This process, which in the quantum-mechanical l...