A deuterium lamp (D₂ lamp) is a low-pressure hot-cathode arc discharge ultraviolet light source widely adopted in analytical spectroscopy. Its emission spectrum originates from electric excitation of deuterium molecules inside the quartz envelope.
When high voltage is applied between electrodes, electrons collide with D₂ molecules to form excited-state deuterium molecules. The excited D₂ molecules dissociate rapidly, releasing energy in the form of photons and generating a continuous ultraviolet spectrum. The standard effective spectral range is 190 nm ~ 400 nm. If equipped with MgF₂ windows, the usable wavelength can extend down to approximately 160 nm vacuum ultraviolet region.
Spectral characteristics:
- Continuous smooth radiation within 190–400 nm, offering high radiant intensity in deep ultraviolet;
- Two prominent sharp emission lines exist at 486.0 nm and 656.1 nm in the visible band, which are commonly used for wavelength calibration of spectrophotometers;
- Light output below 190 nm is restricted by quartz window transmittance.
Compared with hydrogen lamps, deuterium lamps feature stronger UV radiation, longer service life and better stability. Tungsten halogen lamps only supply effective radiation above 350 nm and cannot replace deuterium lamps for ultraviolet testing.
Main applications: UV-Vis spectrophotometer, HPLC UV detector, atomic absorption spectrometer background correction, environmental gas monitoring, liquid sample ultraviolet quantitative analysis, fluorescence excitation light source.
Key precautions: Deuterium lamps require sufficient warm-up time to stabilize spectrum output; avoid frequent switching to extend service lifetime.