NMR Panopticum: Lost Lock Signal

The response of the solvent deuterium signal is monitored to keep its frequency "locked" at a constant value. Loss of the lock signal during acquisition causes the spectrometer to go into a sweep mode, where the magnetic field is swept through a specified range in the hope to locate the deuterium resonance and to reestablish the field-frequency lock.

	Lost lock signal during acquisition, shown here for a proton spectrum.
	Here is another proton NMR example
	Here is a carbon NMR example