  Within the k_t-factorization framework, we study diffractive production of
orbitally excited vector mesons and compare it with the production of radial
excitations, focusing on the rho(1450)/rho(1700) case. At small Q^2, orbital
excitation of light quarkonia is found to dominate over radial excitations in
diffractive production. We predict strong suppression of the production of
orbital excitations by longitudinal photons, which leads to very small
sigma_L/sigma_T ratio. At small Q^2, the s-channel helicity violating
transitions contribute \sim 10-15% of the transverse cross section and \sim 50%
of the longitudinal cross section. We also study mixing between radial and
orbital excitations and determine strategies towards clarification of
S-wave/D-wave assignment to rho(1450) and rho(1700) mesons. The results are
compared with the experimental data available, and predictions for future
experiments are given.
