  Hard diffractive electroproduction of longitudinally polarized vector mesons
is calculated within the leading $\alpha_s\ln{Q^2\over\Lambda_{QCD}^2}$
approximation of QCD using the leading order parton densities within the
nucleon. Novel QCD features of the production of excited states and of the
restoration of flavor symmetry are analyzed. At the onset of the asymptotic
regime, our analysis finds an important role of quark Fermi motion within the
diffractively produced vector mesons, and we suggest to use this effect to
measure the high momentum tail of the wave function of the vector mesons. We
deduce a kinematical boundary for the region of applicability of the
decomposition of the hard amplitudes over powers of $Q^2$ and/or a limit on the
increase of the cross sections of hard processes at small $x$, and briefly
analyze its consequences. We also estimate the nuclear attenuation of the
diffractive electroproduction of vector mesons and compare with estimates of
the shadowing of the longitudinal structure function.
