Multiple pulse response in pure NQR of spin I = [formula omitted] nuclei in single crystals: response to phase-alternated pulse sequence (PAPS)

Abstract

The response of spin I = 3 2 nuclei in a single crystal to phase-alternated pulse sequence (PAPS) t° wl –(τ– t 180° w2—2τ–t 0° w2–τ) N in pure NQR is theoretically investigated. Average Hamiltonian theory is employed to calculate the spin-space averaging of the line-broadening internal interactions. is employed to calculate the spin-space averaging of the line-broadening internal interactions. The criterion employed for spin-space averaging is that the average Hamiltonian during the cycle for the interaction under consideration should commute with the initial density matrix prepared by the pulse t 0° w1 before the first cycle. The average Hamiltonian during PAPS for the main line-broadening interactions, namely electric field gradient (efg) inhomogeneity, torsional oscillations and heteronuclear dipolar interactions, is found to commute with the initial density matrix of the system when 2 t w1 = t w2. It is concluded that during PAPS these internal interactions do not contribute to the linewidth of the pure NQR spectrum of physically equivalent spin I = 3 2 nuclei in a single crystal. These theoretical results are similar to those obtained earlier for spin I = 1 system by Osokin.