https://doi.org/10.1351/goldbook.ET07372
Non-coherent source of @UT07492@ radiation capable of producing quasi-monochromatic radiation from the near UV (\(\lambda = 354\ \text{nm}\)) to the vacuum UV (\(\lambda = 126\ \text{nm}\)). The operation of the @E02242@ lamps relies on the radiative @D01547@ of excimers or exciplexes created by various types of discharges.
Notes:
- Using noble gas, halogen, or noble gas / halogen mixtures with fill pressure \(\sim 30\ \text{kPa}\), the radiative @D01547@ of the @E02242@ or the @E02246@ produces nearly monochromatic radiation. Some of the commercially available wavelengths for the particular excimers or exciplexes are \(126\ \text{nm}\) with Ar2, \(146\ \text{nm}\) with Kr2, \(172\ \text{nm}\) with Xe2, \(222\ \text{nm}\) with KrCl, and \(308\ \text{nm}\) with XeCl, obtained with efficiencies of \(5{-}15\,\%\). Pulsed Xe-@E02242@ (Xe2) lamps may have up to 40 % efficiency. Good efficiencies are also obtained with XeBr at \(291\ \text{nm}\) and with XeI at \(253\ \text{nm}\). Other wavelengths produced with much less efficiency are \(207\ \text{nm}\) (KrBr), \(253\ \text{nm}\) (XeI), \(259\ \text{nm}\) (Cl2), and \(341\ \text{nm}\) (I2) (see Table 1).
Table 1: Peak wavelengths (\(\text{nm}\)) obtained in dielectric-barrier discharges with mixtures of noble gas (Ng) and halogen (X2). Wavelengths of commercially available lamps are shown in boldface type. The molecular species indicated are excimers or exciplexes.
X2 Ne Ar Kr Xe Ng2 126 146 172 F 157 108 193 249 354 Cl 259 175 222 308 Br 291 165 207 283 I 341 190 253 - Phosphors are used to transform the UV radiation into @VT07496@ radiation. This is the basis of mercury-free fluorescent lamps and of flat plasma-display panels with a large screen.