  In this work the production of vector mesons in diffractive DIS is analyzed,
with an emphasis on the impact of the internal spin structure of a vector meson
upon its virtual photoproduction rate. We derived the full sets of s-channel
helicity conserving and violating amplitudes for pure S and D wave vector
mesons and found a striking difference between S and D wave vector meson
production. First, in the case of helicity conserving amplitudes, D wave vector
mesons were found to exhibit dramatically different Q^2-behavior due to
abnormally large higher twist contributions. Besides, we found that helicity
conserving amplitudes for S and D states are numerically comparable, which
makes the physical rho meson very sensitive to D wave admixture. Second, the
helicity violating amplitudes turned out large both for S and D wave states of
light vector mesons and for D wave heavy vector mesons as well.
  Aiming at producing sort of a manual on the diffractive vector meson
production, we carried out all calculations in a pedagogical manner with
maximally full presentation of intermediate steps and accompanied them with
detailed qualitative discussion.
