Design and optimization of THz coupling in zirconia MAS rotors for dynamic nuclear polarization NMR.

ABSTRACT: We present 3D electromagnetic simulations of the coupling of a 250 GHz beam to the sample in a 380 MHz DNP NMR spectrometer. To obtain accurate results for magic angle spinning (MAS) geometries, we first measured the complex dielectric constants of zirconia, sapphire, and the sample matrix material (DNP juice) from room temperature down to cryogenic temperatures and from 220 to 325 GHz with a VNA and up to 1 THz with a THz TDS system. Simulations of the coupling to the sample were carried out with the ANSYS HFSS code as a function of the rotor wall material (zirconia or sapphire), the rotor wall thickness, and the THz beam focusing (lens or no lens). For a zirconia rotor, the B₁ field in the sample was found to be strongly dependent on the rotor wall thickness, which is attribut

SUBMITTER: Li G 

PROVIDER: S-EPMC11482594 | biostudies-literature | 2024 Jul

REPOSITORIES: biostudies-literature