The unfiltered medium pressure mercury lamp provides a broad radiant output of wavelengths between 220 nm and 600 nm. Vapourtec offer a range of 9 wavelength filters for use with the mercury pressure mercury lamp. These allow the selection of desired wavelengths, in addition to eliminating unwanted wavelengths that cause side reactions or the decomposition of products. Filters also have a key role in reducing the heating effect of the lamp.
Wavelength filters are positioned between the lamp and the reactor and can be quickly and easily changed by hand. Both long-pass and band-pass filters are available. A ‘blank’ filter allowing the full spectral output to be transmitted is also available.
Long-pass filters improve reaction selectivity by eliminating shorter wavelengths and transmitting longer wavelengths.
5 long-pass filters are available which are commonly made of Pyrex or quartz. The different materials possess different refractive indices allowing accurate wavelength filtering. This allows detailed exploration of wavelengths for reaction optimisation.
4 band-pass filters are available. These transmit only a specific wavelength band by eliminating both shorter and longer wavelengths.
Band-pass filters are used to provide a wavelength of interest whilst eliminating most of the heating effect of the lamp. This allows lower temperatures to be assessed even when using the high intensity medium pressure mercury lamp.