The Source temperature setting maybe found on the ES Source tab, the Extended tab or the Advanced tab on the Tune page, depending on the instrument. Replace the cartridge heater (part number depends on instrument type, see additional information below). As a safety precaution, set the source temperature to 20 C (the lowest allowable temperature in the SW). Temperature control is essential in spectroscopic experiments because it affects the physical and chemical properties of the. Nuclear magnetic resonance spectroscopy (NMR) is a widely used and powerful method that takes advantage of the magnetic properties of certain nuclei. NMR observes. NMR) Spectroscopy. The concepts implicit and fundamental to the operation of a modern NMR spectrometer, with generic illustrations where appropriate, will be described. Some basic understanding of NMR spect itic ular. Part of the book series: Techniques in Visible and Ultraviolet Spectometry ( (TVUS,volume 2)) The fluorescence efficiency of many compounds is very sensitive to temperature variations and for accurate work, temperature regulation is necessary [1, 2]. necessary, until the digestion is complete (generally indicated when the digestate is light in color or does not change in appearance with continued refluxing).