Dwell Time and Pulse Interval

The sampling time during which FID data points must be collected in order to obtain the true NMR spectrum after Fourier transformation depends on the spectral width A. According to information theory [18], the sweep time per data point, called the dwell time faw, must satisfy the minimum given by the Nyquist equation (2.12). 

Following this relation, the spectral width of A = 5 kHz often used in 13C NMR requires a dwell time of 100 ps. Multiplying the dwell time with the number of data points N to be collected during the FID yields the acquisition time z required for recording the interferogram digitally. 

When several pulse interferograms must be accumulated in order to improve the signal noise ratio, x is the minimum repetition time between two pulses or the minimum pulse interval. 

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