NMR

These notes include a general introduction to Bruker TopSpin software, and a step-by-step guide to the acquisition and processing of 1D spectra. It is by no mean a replacement for the short training course each user is obliged to take.

The nomenclature of parameters as described in Pulprog.info.

For a pulseprogram the first characters (usually up to 6, but sometimes more) specify the type of experiment, e.g. DEPT, COSY,NOESY etc..
Further properties of the pulseprogram are indicated by a two-character code, which is added to the name in alphabetical order.

• edc- edit current data set (can be used to copy current data set parameters into a new name)
• eda- edit acquisition parameters
• edp- edit processing parameters
• edo- edit output device (printer/plotter)
• edg- edit graphics, the plotting parameters
• acqu [a]- go to the acquisition menu
• ased- edit acquisition parameters relevant to the current pp
• edasp- edit the rf routing (the channels)

¹H hard pulse
¹H selective pulse (water Flip Back, FB, pulse)
¹⁵N hard pulse (inverse mode)
¹³C hard pulse (inverse mode)
¹³C selective 90 pulse (shaped pulse)
¹³C selective inversion (180) pulse (shaped pulse)
²H decoupling pulse
Calibrated Pulse-Length Values

Introduction
System Overview
Safety  &  Emergency
Controls on the CryoCooling Unit
Instructions for AVIII800/CryoProbe Users

Molecular Associations can lead to shifts in the NMR spectra. This effect is particularly strong, when hydrogen bonding is involved. The shifts are concentration dependent and temperature dependent. This fact is used when calibrating the actual temperatures in your sample with methanol (low temperature range, 178-330K) and/or ethylen glycol (high temperature range, 273-416K).

We have used neat methanol as our thermometer substance, and measured the frequency difference between its two peaks to calculate the actual sample temperature.

• Calibrated pulse lengths for NEO-1000 probes
• Calibrated pulse lengths for AVIII-800 probes
• Calibrated pulse lengths for NEO-600 probes
• Calibrated pulse lengths for AV-500 probes
• Calibrated pulse lengths for AVIII-400 probes
• Calibrated pulse lengths for AVIII-300 probes
• Pulse Calibration Procedures

In the context of NMR, the shims are small magnetic fields used to cancel out errors in the static magnetic field. These minor spatial inhomogeneities in the magnetic field could be caused by the magnet design, materials in the probe, variations in the thickness of the sample tube, sample permeability, and ferromagnetic materials around the magnet. A shim coil is thus designed to create a small magnetic field which will oppose and cancel out an inhomogeneity in the B o magnetic field.

Detection of the solute signal (typically proton concentration of 1-2 mM) in the presence of solvent signal (for water, proton concentration ~110M) presents a difficult problem since the dynamic range of the electronic components of the spectrometer is limited.
Three methods exist for suppressing unwanted signals of the solvent (dynamic range reduction):