  It was already experimentally demonstrated that high-energy electrons can be
generated using metal nanotips as active media. In addition, it has been
theoretically proven that the high-energy tail of the photoemitted electrons is
intrinsically linked to the recollision phenomenon. Through this recollision
process it is also possible to convert the energy gained by the laser-emitted
electron in the continuum in a coherent XUV photon. It means the emission of
harmonic radiation appears to be feasible, although it has not been
experimentally demonstrated hitherto till now. In this paper, we employ a
quantum mechanical approach to model the electron dipole moment including both
the laser experimental conditions and the bulk matter properties and predict is
possible to generate coherent UV and XUV radiation using metal nanotips as
sources. Our quantum mechanical results are fully supported by their classical
counterparts.
