Components: Acquisition Time [at]

After the radiofrequency pulse has been applied to the sample and turned off, the spins return to thermal equilibrium, and in the process induce a signal in the receiver coil. In Figure II-1, the decaying sine wave depicts this signal called the Free Induction Decay or FID. The FID is a plot of the intensity of the induced signal as a function of time, and is commonly referred to as the time-domain data. The time spent in acquiring the FID is called the acquisition time (at). The FID, which is an analog signal is digitized using an analog-to-digital converter which represents the FID by a series of points along the FID curve. The number of points thus used can be entered by setting np to the proper value on the Unity+300 and VXR-S 400 NMR spectrometers. As a general rule, more points result in higher resolution.