Temperature Distribution in a Solid State NMR Sample Rotor during MAS Experiments

Abstract

We investigated temperature distribution in a solid state nuclear magnetic resonance (NMR) sample rotor under magic angle spinning (MAS) experiments by analyzing the ²⁰⁷Pb chemical shift of solid lead nitrate (Pb(NO₃)₂). The analysis corrected a mismatch of the temperature dependence of ¹H spin-lattice relaxation time (T₁^H) obtained from different sample positions in the rotor. We prepared three rotors that consisted of Pb(NO₃)₂ partitioned into the three different parts with Teflon spacers, and measured the temperature distribution related to the placement using the prepared three rotors. The obtained temperature distribution showed a large gradient in the sample rotor. The temperature distribution was related to the placement in the rotor and successfully visualized. Finally, the divergent temperature dependence of T₁^H obtained at different placement positions in the sample rotor was successfully corrected to accurate temperature dependence.