论文标题
观察到时间依赖性磁场中CPMG序列的绝热和非绝热行为
Observation of adiabatic and non-adiabatic behavior for CPMG sequence in time-dependent magnetic fields
论文作者
论文摘要
我们通过实验研究时间依赖磁场对Carr -Purcell -Meiboom -Gill（CPMG）序列的自旋动力学的影响。在广泛的偏移场和坡道速率上，测得的响应与绝热行为完全一致。回声振幅表现出与理论预测非常吻合的特征调制。在不同的偏移量下观察到非绝热事件。通过这些偏移突然，实验结果偏离了理论绝热表达。这些非绝热事件恰好发生在理论上预测的现场抵消。证明在绝热状态下，场波动的影响是完全可逆的，而非绝热事件的发生导致滞后。可以通过修改CPMG序列中的重新聚焦脉冲来增加田间偏移的绝热范围。
We investigate experimentally the effect of time dependent magnetic fields on the spin dynamics of the Carr - Purcell - Meiboom - Gill (CPMG) sequence. Over a wide range of offset fields and ramp rates, the measured response is fully consistent with adiabatic behavior. The echo amplitudes exhibit characteristic modulations that are in excellent agreement with theoretical predictions. Non-adiabatic events are observed at distinct offsets. Abruptly after passing through these offsets, the experimental results deviate from the theoretical adiabatic expressions. These non-adiabatic events occur precisely at the field offsets predicted by theory. It is demonstrated that in the adiabatic regime the effects of field fluctuations are fully reversible, while the occurrence of non-adiabatic events leads to hysteresis. The adiabatic range of field offsets can be increased by modifying the refocusing pulses within the CPMG sequence.
