Suppressing Background 13C NMR Signal From the Probe Head by Phase Incremented Pulses

Abstract

The background 13C NMR signal originated from the organic materials in the probe head cross-polarizes from 1H nucleus to 13C nucleus. This background 13C NMR signal is very broad (δC 20~250) and accumulates as the sample signal accumulating. Hartman-Hahn cross polarization with phase-incremented pulses in the S spin channel (denoted as PIPCP) is developed to suppress this background signal. The application of PIPCP results in severe phase distortion outside the radio frequency coil such that the background 13C NMR signal cannot cross polarize and thus be suppressed. In comparison, depending on the dipolar coupling constant between 1H and 13C nuclei, PIPCP induces only a small amount of Hartman-Hahn mismatch (1.4%) to the desired signals.

Keywords

• solid-state nuclear magnetic resonance
• background signal suppression
• phase incremented pulses
• cross polarization