•For UV-vis absorption
spectrophotometry usually use H2 for UV and tungsten for visible
region (switching mid scan)
•Sometimes use D2 instead of H2
•For fluorescence
spectrophotometry use xenon arc lamp in scanning
instruments
•Can use He below 200
nm
•Hg at low pressure is
used in fixed wavelength (non scanning) fluorometers
•Can use mixture of Hg
and Xe