Department of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland.
Solid State Nucl Magn Reson. 2011 Feb-Apr;39(1-2):1-6. doi: 10.1016/j.ssnmr.2011.02.002. Epub 2011 Mar 10.
The non-cyclic geometric phase of ¹⁴N and ³⁵Cl NQR signals induced by the character of trajectory of nuclear magnetization motion upon pulse r.f. excitation of powdered samples is studied. Analytical expressions for the geometric phases of NQR signals of the nuclei of spins I=1 and 3/2 upon nuclear magnetization rotation induced by means of r.f. pulses with frequency detuned from the resonance and for any impulse duration for a separate crystallite are obtained. It is shown that the geometric phase recorded for the signal from a powdered sample at Δω=0 can be different from zero and can oscillate upon changes in duration of the r.f. excitation pulse. An alternative variant of the nutation experiment aimed at obtaining the asymmetry parameter η from locations of frequency singularities in the nutation phase spectrum for nuclei of spin I=3/2 in powder substances is proposed.
研究了在粉末样品的射频激发下，核磁化运动轨迹的特征引起的¹⁴N 和 ³⁵Cl NQR 信号的非循环几何相位。推导出了在与共振频率失谐的射频脉冲作用下，通过核自旋 I=1 和 3/2 的核自旋核的核自旋磁化旋转诱导的 NQR 信号的几何相位的解析表达式，以及对于单个晶胞的任何脉冲持续时间的表达式。结果表明，在Δω=0 时从粉末样品记录的信号的几何相位可以不为零，并且可以在射频激发脉冲持续时间变化时发生振荡。提出了一种改进的章动实验的变体，旨在从粉末物质中自旋 I=3/2 的核的章动相位谱中的频率奇异点的位置获得不对称参数 η。
