Pure nuclear quadrupole resonance determination of the electric field gradient asymmetry for broad lines

摘要

We present an angle dependent nuclear quadrupole resonance (ADNQR) method to determine the electric field gradient asymmetry parameter η in systems where the resonance line is so broad that the radio frequency field can excite only a portion of the nuclear spins. In this situation, the recently developed spectroscopic methods are not applicable. ADNQR is useful for single crystals and oriented powders, and, for small determines η~4. Therefore, it can be used to evaluate fluctuations in η due to inhomogeneities. We demonstrate the application of ADNQR experimentally to oriented superconducting YBa_2Cu_3O_7 powder.