高转速下采用S-RESIDOR方法测量1H-27Al偶极偶合常数

摘要

提出利用S-RESIDOR(Symmetry-based Resonance Echo Saturation Irradiation DOuble Resonance)方法测量1 H-27 Al偶极偶合常数.通过理论模拟,讨论了四极作用常数、饱和照射脉冲功率、照射时间对1 H/27 Al S-RESIDOR实验的影响.发现四极作用常数对1H/27 Al SRESIDOR偶极去相曲线影响较小,中等强度的饱和照射功率即能满足实验要求.高转速下,在氢型丝光沸石上进行了1 H/27 Al S-RESIDOR实验,测量得到Bronsted酸位上的1H与骨架上27Al的偶极偶合常数为874 Hz.%A Symmetry-based Resonance Echo Saturation Irradiation DOuble Resonance (S-RESIDOR) method is proposed for measuring 1 H-27 Al dipolar coupling constant in zeolite. The influence of 27A1 Cq value, v1(27 Al) and the saturation pulse length of 27A1 channel on the 1H/27A1 S-RESIDOR experiment were discussed. Numerical simulations indicate that 1H/27A1 S-RESIDOR dephasing curves are insensitive to the 27A1 quadru-pole coupling constant, and moderate RF field can fulfill the experiment requirements. The 1H/27A1 S-RESIDOR experiment was performed on H-mordenite under fast spinning speed, and the measured 1H/27A1 dipolar coupling constant is 874 Hz.