  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/A and pulse durations ranging from ~ 1 fs to ~ 10 ns for
film thickness 3 to 10 nm.
