  We report optical absorption and photoluminescence spectra of Au, Fe, Co and
Ni polycrystalline nanofilms in the UV-Vis-NIR range, featuring discrete bands
resulting from transverse quantum confinement. The film thickness ranged from
1.1 to 15.6 nm, depending on the material. The films were deposited on fused
silica substrates by sputtering and thermo-evaporation, with Fe, Co and Ni
protected by a SiO2 film deposited on top. The results are interpreted within
the particle-in-a-box model, with the box width equal to the mass thickness of
the nanofilm. The transverse-quantized energy levels and transition energies
scale as the inverse square of the film thickness. The calculated values of the
effective electron mass are 0.93 (Au), 0.027 (Fe), 0.21 (Co) and 0.16 (Ni), in
units of the mass of the free electron, being independent on the film
thickness. The uncertainties in the effective mass values are ca. 2.5%,
determined by the film thickness calibration. The second calculated model
parameter, the quantum number n of the HOMO, was thickness-independent in Au
(5) and Fe (6), and increased with the film thickness in Co (from 7 to 9) and
Ni (from 7 to 11). The transitions observed in absorbance all start at the
level n and correspond to {\Delta}n = +1, +2, +3, etc. The photoluminescence
bands exhibit large Stokes shifts, shifting to higher energies with the
increased excitation energy. The photoluminescence quantum yields grow linearly
with the excitation energy, showing evidence of multiple exciton generation. A
prototype Fe-SnO2 nanofilm photovoltaic cell demonstrated at least 90% quantum
yield of photoelectrons at 77K.
