  The relation between the ratio Gamma_{ee}(psi')/Gamma_{ee}(J/psi) and
Gamma_{2gamma}(eta_{c}')/Gamma_{2gamma}(eta_{c}), expressed in terms of the
configuration mixing amplitudes induced by the contact spin-spin interaction of
quarks in the ground and radial excitation states, is shown to give, after the
inclusion of the newly derived relativistic corrections, the radiative
eta_{c}'- and \eta_c-width ratio in fair accord with recent experiments. The
dynamical model is proposed to derive the ratio of relative probability of the
ground (eta_{c}(2980))- and first radial excitation (eta_{c}'(3640))-state
formation in gamma-gamma collisions followed by their decay into the pi\bar{K}K
and p\bar{p} channels.
