Off-resonance effects and selectivity profiles in pulsed nitrogen-14 nuclear quadrupole resonance

Area of Science:

• Nuclear Quadrupole Resonance (NQR) Spectroscopy
• Physical Chemistry
• Spectroscopic Techniques

Background:

• Baseline distortions in nitrogen-14 NQR spectra can arise from pulse breakthrough.
• Standard radio-frequency (rf) pulse power in NQR is higher than necessary for certain applications.

Purpose of the Study:

• To investigate the application of low power radio-frequency (rf) pulses for alleviating baseline distortions in nitrogen-14 NQR spectra.
• To develop a theoretical framework explaining the efficacy of low power pulses in NQR.

Main Methods:

• Application of low power radio-frequency (rf) pulses in nitrogen-14 NQR experiments.
• Development of theoretical models to explain experimental observations.
• Comparison of rf power requirements and selectivity profiles between NQR and Nuclear Magnetic Resonance (NMR).

Main Results:

• Low power rf pulses significantly reduce baseline distortions caused by pulse breakthrough in nitrogen-14 NQR.
• NQR requires four times less power than equivalent NMR experiments due to active rf field amplitude differences.
• NQR exhibits a more favorable selectivity profile compared to NMR in most cases.

Conclusions:

• Low power NQR is a feasible and recommended technique for most applications.
• The effectiveness of low power NQR is dependent on the NQR signal's line-width.
• Theoretical validation supports the experimental findings on low power NQR.