A quantum-mechanical treatment of the angular motion in dinuclear systems (DNS) formed during fission is proposed. This motion determines the mechanism for generating the angular momentum of the fission products. Numerical diagonalization of the DNS Hamiltonian revealed that the fragment motion approximately corresponds to the independent vibrations around the pole-to-pole configuration, rather than to the bending and wriggling modes, as previously assumed. The proposed mechanism explains the recently discovered lack of correlations between the angular momenta of fission fragments and the sawtooth shape of the dependence of angular momentum on the fragment mass. Considering the angular motion in DNS formed at scission point allowed us to describe successfully new experimental data indicating a weak interdependence between the total kinetic energy and angular momentum of ¹⁴⁴Ba formed in the spontaneous fission of ²⁵²Cf.

(To be nominated for the JINR Prize 2025)