Experiment Setup in NMR-SIM

The information that may be obtained from an NMR spectrum depends to some extent on the experimental parameters used to record the spectrum. Before recording an NMR spectrum a number of acquisition parameters have to be defined which depend on both the type of sample and the pulse sequence being used. Often the various parameters interact with each other making the optimization of the acquisition parameters difficult. Once the data has been acquired it may be processed and analysed in a number of different ways to extract the required information. 

NMR-SIM can be seen as a software tool to analyse separately the effects on a NMR spectrum of different experimental variables such as spin system, pulse sequence and experimental parameters. The simulation program reduces the number of experimental parameters to a minimum to resemble as closely as possible a real experiment. This reduction in the number of variable parameters is a basic principle of scientific research because often the relationship between only a limited number of parameters can be interpreted unambiguously. The parameter reduction also speeds up calculation time. As illustrated in Fig. 4.1 the NMR spectrometer, represented by the magnet and computer, can be replaced by a computer plus software and the NMR sample by a defined theoretical spin system. Such an ideal spectrometer is the basis of the NMR-SIM or NMR experiment simulator software tool. 

NMR Spectroscopy Data Acquisition, Second Edition. C. Schorn, B. Taylor Copyright 2004 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 3-527-31070-3 

Magnetic field inhomogenity, field drift or temperature fluctuation effects cannot be calculated but other experimental effects such as incorrectly set pulse lengths or phases that the NMR spectroscopist may come across can be easily simulated. 

In the first section of this chapter spin systems and pulse sequences are discussed. Starting with the definition of a spin system and a description of the various spin parameters used by NMR-SIM. Using suitable examples the correct definition of spin system parameters, how to reduce the number of spin system parameters and the application of variable spin system parameters is illustrated. Following on, pulse sequences are discussed in some detail and the difference between a pulse sequence and a pulse program is emphasized. The pulse program language of NMR-SIM should be familiar to users of Bruker NMR spectrometers as it uses the same syntax. However, because this is not covered in the NMR-SIM manual, pulse sequence elements such as pulses, phases and delays are explained in detail and illustrated using a variety of examples. 

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This section examines some of the general experiment parameters required to create a 2D data matrix and the special experiment setup in NMR-SIM. The most important experimental parameters are inO, NS, delays di and the type of quadrature detection in fl. The user-related entries for the experiment setup are ... 

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