  We present a detailed analysis of rho(0) electroproduction at intermediate
energy for quasi-elastic knockout kinematics. The approach is based on an
effective Lagrangian which generates exchanges of scalar, pseudoscalar,
axial-vector and tensor mesons. The specific role of mesons with different
values for J(PC) is analyzed. We show that the pi(0) exchange amplitude and its
interference terms with eta(eta') and f1 exchanges dominate in the transverse
part of the cross section sigmaT. The main role plays the pi(0) to rho(0) M1
spin transition when coupling the virtual photons to the nucleon. In contrast,
the longitudinal cross section sigmaL is generated by a series of scalar meson
exchanges. To extract the dominant term more detailed information on the inner
structure of scalar mesons is required. It turns out that recent data of the
CLAS Collaboration on sigmaL and sigmaT can be described with reasonable
accuracy if one proposes the quarkonium structure for the heavy scalar mesons
(M > 1.3 GeV). On this basis the differential cross sections dsigmaL/dt and
dsigmaT/dt are calculated and compared with the latest CLAS data.
