Jul 29, 2025
Version 2
- Alexander L. Paterson1
- 1National Magnetic Resonance Facility at Madison (NMRFAM), University of Wisconsin-Madison, Madison, WI, United States
Protocol Citation: Alexander L. Paterson 2025. DEPTH. protocols.io https://dx.doi.org/10.17504/protocols.io.bp2l62xb1gqe/v2Version created by NMRFAM Facility
License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
We use this protocol and it's working
Created: May 30, 2025
Last Modified: July 29, 2025
Protocol Integer ID: 219200
Keywords: Background Suppression via Depth Pulses, direct polarization experiments on nuclei, background signals via the depth composite pulse, direct polarization experiment, depth composite pulse, quadrupolar nuclei, b1 field of the probe, nuclei, utilities for quadrupolar nuclei, spectrum, probe, significant background signal, probe material, intensities of the peak, peak, depth purpose, suppressing background signal
Funders Acknowledgements:
National Science Foundation
Grant ID: 1946970
Abstract
Purpose
To acquire a spectrum while suppressing background signals via the depth composite pulse.
Scope
This sequence is intended for direct polarization experiments on nuclei with significant background signals arising from probe materials, e.g., 1H, 19F, 13C, 29Si, 11B, among others. It will be most effective in spin-1/2 systems, and may have limited utilities for quadrupolar nuclei such as 11B. If the B1 field of the probe is not sufficiently homogeneous, this sequence can have an effect on the relative integrated intensities of the peaks in the spectrum.
Guidelines
Depth pulses will typically result in reduced sensitivity as compared to a conventional Bloch decay experiment. The exact reduction will depend on the B1 homogeneity of the probe being used.
Materials
Definitions:
- B1: Applied magnetic field
- T1: Spin-lattice relaxation time constant
Troubleshooting
Before start
The user should be familiar with optimizing 90° pulses, power limits, and the probe duty cycle.
Expected amount of time SOP will use: 1 hour or less
Procedure
Set the 90° pulse length, p1, and pulse power, plw1, to previously optimized values.
Set the recycle delay, d1, to either 1.3 × T1 for optimal sensitivity or 5 × T1 for accurate relative quantitation.
If heteronuclear decoupling is required:
Set zgoptns to -Ddec.
Set the decoupling program, cpdprg2, and pulse length, pcpd2, to previously optimized values.
If presaturation is required:
Set zgoptns to -Dpresat.
Set the presaturation comb delay, d20, to a previously optimized value. This value will depend on the system and nucleus under investigation. For 1H, 1 ms may be reasonable.
Set the number of presaturation pulses, l20, to a previously optimized value. A reasonable default value is 20.
Set the number of scans, ns, to a multiple of 16; this should be high enough to achieve adequate signal-to-noise ratio.
Acquire the spectrum.
Protocol references
Cory, D. G.; Ritchey, W. M. Suppression of signals from the probe in Bloch decay spectra. Journal of Magnetic Resonance (1969) 1988, 80 (1), 128-132. DOI: 10.1016/0022-2364(88)90064-9.
Example Data at 1.1 GHz: usnan.org/ark:/83454/e1579bc8d0-2578-4bab-823b-af67ed790fc5
Example Data at 900 MHz: usnan.org/ark:/83454/e121391eba-856d-4f55-9c57-d12bf20acd09
Example Data at 600 MHz: usnan.org/ark:/83454/e1e3628846-54b8-42d7-901e-cade3f72a037