The incorporation of delays into NMR pulse sequences involving heteronuclear systems allow the free evolution of chemical shift and heteronuclear coupling constants similarly as the homonuclear case.

An example should be the variable evolution period in TROSY-type experiments. Thus, due to free evolution of any NMR parameter during this variable t₁ period, all homonuclear and heteronuclear information is present in the F₁ dimension of these spectra.

Alternatively, 180º pulses placed into heteronuclear pulse sequences can be used to refocus a desired chemical-shift, homo- or heteronuclear J-coupling information, depending of the position into the pulse sequence and on the nuclei that they are applied.

REQUIREMENTS

Easy implementation on AVANCE spectrometers.

EXPERIMENTAL DETAILS

There are 32 duration parameters, d0-d31,  to be specified in seconds. They are executed as delays without any further actions by the pulse program commands d0. They can be incremented or decremented using the pulse program commands id0-id31 or dd0-dd31, respectively. The changes are given by the parameters IN0-IN31. The pulse program commands rd0-rd31 reset a respective delay to its original value. The delays may also be changed by means of arithmetic expressions during pulse program execution.

 SYNTAX

The standard way to implement a variable evolution delay in a pulse program is:

... d0 ...

in which d0 is, in the BRUKER format, the variable evolution delay (in seconds) in multidimensional experiments.

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