In solid-state NMR, homonuclear dipolar couplings contribute greatly to the broadening of 1H spectral line shapes. Even at the fastest magic-angle spinning rates (MAS) available today [100-150kHz], the linewidths still extend over several hundred Hertz, limiting the 1H resolution. Reducing this contribution could provide rich structural information for organic solids. Recently, we demonstrated that the Anti-Z COSY experiment, in addition to MAS, is able to reduce the line broadening on organic solids by a factor of two, when compared to the MAS conventional spectra. To understand better the results obtained, theoretical studies with average hamiltonian theory (AHT) help to analyse the behaviour of the 1H spins under MAS, but also to open the way to design new experiments to reduce the linewidth. The AHT treatment has been developed to 3rd order for two and three spins and we were able to retrieve a fully analytical expression. The aim of this thesis is to develop further new experiments to obtain narrower linewidths in 1H NMR while simultaneously continuing the theory treatment explaining the results obtained.