Feb 17, 2025

Public workspaceDEPTH

This protocol is a draft, published without a DOI.
  • Alexander L. Paterson1
  • 1National Magnetic Resonance Facility at Madison (NMRFAM), University of Wisconsin-Madison, Madison, WI, United States
NMRFAM Facility
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Protocol Citation: Alexander L. Paterson 2025. DEPTH. protocols.io https://protocols.io/view/depth-dd7k29kw
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: In development
We are still developing and optimizing this protocol, but it should be functional. We hope to solicit feedback primarily on clarity and usability. We intend to publish it in June 2025.
Created: May 22, 2024
Last Modified: February 17, 2025
Protocol Integer ID: 100300
Keywords: Background Suppression via Depth Pulses
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:
  1. B1: Applied magnetic field
  2. T1: Spin-lattice relaxation time constant

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
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.


Protocol
Saturation Recovery with Half-Echo Acquisition
NAME

Saturation Recovery with Half-Echo Acquisition

CREATED BY
NMRFAM Facility