13C CP/MAS: Application to glycine

Abstract

AbstractIn a previous article (Concepts Magn Reson 22A(1) 37–49 (2004)), the initial setup of the 13C CP/MAS experiment was described. The advantages of the experiment over direct 13C excitation were also given. In this article, the experiment is applied to three polymorphic structures of glycine. Temperature calibration of the experiment to investigate molecular dynamics as a function of temperature is also described. Though the 13C CP/MAS experiment is widely applicable, it cannot be universally used. The 13C CP/MAS experiment works at ambient temperature for both the α and γ polymorphic structures of glycine. However, the cross‐polarization technique fails to provide a signal at low temperature from either polymorph. The failure of the technique for both polymorphs arises from the shortened 1H T1ρ at low temperatures. This shortened T1ρ results from the hindered rotation of the −NH3 group. The technique even fails at ambient temperature for β‐glycine. Again, the reason is a shortened 1H T1ρ. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson Part A 22A: 79–89, 2004