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  MONITORING PROGRESS
       
  Observe data acquisition.
Once your sample(s) have been locked and shimmed, and the receiver gain has been optimized, the actual acquisition of the NMR signal can be begun.
 
The icon shown at right blinks when data is being acquired. A few test scans are first run, then the pulse sequence specified by the selected experiment is repeated many times, specified by the parameter NS (number of scans). Before the run, the icon will be labeled "Acquire Data". During the experiment, it will read "ZG in Progress"; ZG stands for "zero and go". At the conclusion of the experiment, the message will say "ZG Done".

(Click on the icon to learn more about this step)
     
  It is often helpful to observe the NMR signal, and the resulting spectrum, during the course of the experiment. Clicking on the "i" button at the top of the sample entry screen (it is in the same row as the green "Go" button) brings up an online control window, shown below (a larger version is here):
   
  Note that this window provides much useful information about the acquisition in progress, including the name, time remaining, and experiment name. The command buttons in the bottom half allow you some control over what you see during the experiment. At any point, controls that are inactive are shown in gray. When data is being acquired, clicking on the "FID" button brings up a window like the one below (larger version here), which shows the time (x-axis) - voltage (y-axis) signal detected by the receiver: As time goes on, this signal will grow; position your mouse over the FID to see this effect.
   
       
    While the shape of the FID conveys some useful information, to most chemists, the NMR spectrum more helpful than the FID. Clicking on the "Spectrum" button in the online controls window executes a Fourier Transform, which converts the FID into a normal chemical shift (frequency) - intensity spectrum. The system first displays an unphased version, which usually exhibits a twisted baseline (larger version).
 
 
    However, this is quickly corrected to give a properly phased spectrum (roll your mouse over the image above to watch this happen).
       
    The remaining controls allow you to plot out the FID or spectrum as displayed, to temporarily halt execution of your experiment, or to terminate the acqusition. Be aware that, if you stop the experiment, the system will proceed to the next experiment in the queue.