Experimental aspects of ^(14)N overtone RESPDOR solid-state NMR spectroscopy under MAS beyond 60 kHz  

作　　者：Yutaro Ogaeri Yusuke Nishiyama 

机构地区：[1]JEOL Ltd.,Akishima,Tokyo,196-8558,Japan

出　　处：《Magnetic Resonance Letters》2024年第1期40-49,共10页磁共振快报（英文）

摘　　要：Nitrogen-14(^(14)N)overtone(OT)spectroscopy under fast magic angle spinning(MAS)conditions(>60 kHz)has emerged as a powerful technique for observing correlations and distances between ^(14)N and ^(1)H,owing to the absence of the first-order quadrupolar broadenings.In addition,^(14)N^(OT) allows selective manipulation of ^(14)N nuclei for each site.Despite extensive theoretical and experimental studies,the spin dynamics of ^(14)N^(OT) remains under debate.In this study,we conducted experimental investigations to assess the spin dynamics of ^(14)N^(OT) using the rotational-echo saturation-pulse double-resonance(RESPDOR)sequence,which monitors population transfer induced by a^(14)N^(OT) pulse.The ^(14)N^(OT) spin dynamics is well represented by a model of a two-energy-level system.Unlike spin-1/2,the maximum excitation efficiency of ^(14)N^(OT) coherences of powdered solids,denoted by p,depends on the radiofrequency field(rf-field)strength due to orientation dependence of effective nutation fields even when pulse lengths are optimized.It is also found that the p factor,contributing to the ^(14)N^(OT) spin dynamics,is nearly independent of the B0 field.Consequently,the filtering efficiency of RESPDOR experiments exhibits negligible dependence on B0 when the ^(14)N^(OT) pulse length is optimized.The study also identifies the optimal experimental conditions for ^(14)N^(OT)/^(1)H RESPDOR correlation experiments.

关 键 词：^(14)N OVERTONE RESPDOR ^(14)N/^(1)H correlation Solid-state NMR Fast MAS 

分 类 号：O482.532[理学—固体物理]