Decoupling Software Parameters

Most Varian decoupling parameters start with the letter d to distinguish them from the transmitter parameters, which start with a t. Bruker uses a 1 (FI channel) to specify the transmitter channel and a 2 (F2 channel) to specify the decoupler channel. The following parameters can be examined by entering dg (Varian) or eda (Bruker)  

Bruker has no corresponding parameter for dm and homo because these options are written into each pulse program. 

The Varian parameter dmm determines whether the decoupler output is a simple continuous irradiation (dmm = c ) or a pulsed waltz-16 modulation (dmm = w ). For nonselective ( broadband ) decoupling such as that desired for a ID 13C spectrum, the waltz-16 mode is 

There are more advanced experiments such as DEPT (Chapter 7) that observe 13 C and use the decoupler to supply high power, short duration ( hard ) pulses at the XH frequency. This requires full power from the decoupler, but the parameters dpwr andpll7 are avoided for these pulses. Setting decoupler power to the maximum might lead to disastrous mistakes because the decoupler can only deliver full power for short ( 10 pis) periods of time without burning up the decoupler, the probe, and the sample. Instead, the parameters pp (Varian) and p3 (Bruker) are used for the 90° pulse width for decoupler hard pulses and pplvl (Varian) and pl2 (Bruker) indicate the power level for short-duration high-power decoupler pulses. 

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The spectrometer supports phase cycling, asynchronous sequence implementation, and parameter-array experiments. Thus, most standard solid-state NMR experiments are feasible, including CPMAS, multiple-pulse H decoupling such as TPPM, 2D experiments, multiple-quantum NMR, and so on. In addition, the focus of development is on its extension of, or modification to, the hardware and/or the software, in the spirit of enabling the users to put their own new ideas into practice. In this paper, several examples of such have been described. They include the compact NMR and MRI systems, active compensation of RF pulse transients, implementation of a network analyzer, dynamic receiver-gain increment,31 and so on. 

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