Characterization and suppression techniques for degree of radiation damping in inversion recovery measurements

TL;DR

This paper investigates how radiation damping affects T1 measurements in inversion recovery experiments, demonstrating its dependence on T1, characterizing its severity with RADDSY, and suppressing it with GIR at high magnetic fields.

Contribution

It introduces the use of RADDSY and GIR techniques to characterize and suppress radiation damping effects in T1 measurements, highlighting the dependence on T1 and discrepancies in existing models.

Findings

RD effects become significant for T1 > 50 ms

Severe distortions occur for T1 > 150 ms

Discrepancy found in published RD characteristic time expressions

Abstract

Radiation damping (RD) has been shown to affect T1 measurement in inversion recovery experiments. In this work, we demonstrate that the extent of RD depends upon the T1 of the sample. RD difference spectroscopy (RADDSY) is used to characterize the severity of RD, while gradient inversion recovery (GIR) is used for RD suppression in T1 measurements. At 9.4 T, for the radiation damping characteristic time (Trd) of 50 ms, these investigations show non-negligible RD effects for T1 values greater than Trd, with severe distortions for T1 longer than about 150 ms, showing reasonable agreement with the predicted Trd. We also report a discrepancy between published expressions for the characteristic RD time.