14N and 35Cl double resonance study of the phase transition in the intercalated bilayer compound C10H21NH3Cl

The pure nuclear quadrupole (NQR) spectra of 14N, 35Cl, and 37Cl have been measured in C10H21NH3Cl as a function of temperature. The chlorine NQR frequency νQ (35Cl)=1215 kHz at 47 °C is determined by the N–H––Cl hydrogen bonds and is the lowest reported so far. The 14N quadrupole coupling data e2qQ/h=760 kHz. η=0 shows that the C–N–H––Cl backbone is practically rigid at this temperature. Above 53 °C the effects of the phase transition from an intercalated to a nonintercalated structure show up in the N–H––Cl backbone as a sharp drop of the NQR frequencies to ∼60% of their rigid lattice values. A model accounting for this effect has been proposed.