Influence of Three-Spin Groups on the Primary Echo in Linear Polymers with Free Ends

Abstract

Based on the previously developed theory of the free induction decay and spin echo, the theory of the primary echo in flexible-chain polymers with isolated groups of three spins with arbitrary constants of dipole-dipole interaction (DDI) is proposed. The possibility of using the general theory of spin echoes in multispin systems is shown. A method is proposed for assessing the effect of three-spin groups on the shape of the line (NMR) at different temperatures from the integrated signal intensity. It is shown that with increasing temperature, no difference in the effect of identical or arbitrary values of the DDI constants on the spectrum is observed.