WAVELENGTHS: 320NM-265NM
Absorption spectroscopy relies on the wavelength-dependent attenuation of light for specific materials following the Beer-Lambert Law. This enables concentration measurements for applications such as gas-sensing. Several hazardous gases such as Ozone, NO2, SO2, and the BTEX (benzene, toluene, ethylbenzene and xylene) gases show an absorption peak in the UV range as shown in the figure and so absorption spectroscopy using UV light has been used in pollution monitoring and in industry applications to ensure worker safety by detecting the presence and concentration of such gases.
UV LEDs provide wavelength selectivity, narrow-band spectral output, directional emissions and a compact-form factor making them an ideal choice for spectroscopy.
While ultraviolet gas discharge lamps, specifically deuterium lamps, have been primarily used for spectroscopic applications, these lamps suffer from low lifetimes, high costs, bulky form-factors and complex electronics, which make them less than ideal candidates for this application.
Narrow bandwidths (<30nm) and portability, rapid response times along with a stable light-output and precision optics along with the continual efficiency and optical output improvements, and the ability to provide higher power densities (as compared to deuterium lamps) when coupled with fiber-optics, UV LEDs present themselves as an optimal choice for spectroscopy applications.
Commercially available in a number of different wavelengths, form-factors, and beam angles, and with controllable intensities and the ability to modulate at high frequencies provide UV LEDs a significant advantage over other the lamp sources.
References
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6929016/
[2] “III-Nitride Ultraviolet Emitters, Technology and Applications”, book
