A photochemical reactor for studies of atmospheric kinetics and spectroscopy has been built at the
Copenhagen Center for Atmospheric Research. The reactor consists of a vacuum FTIR spectrometer
coupled to a 100 L quartz cylinder by multipass optics mounted on electropolished stainless steel end
flanges, surrounded by UV-A, UV-C and broadband sun lamps in a temperature-controlled housing. The
combination of a quartz vessel and UV-C lamps allows higher concentrations of O(1D) and OH than can
be generated by similar chambers. The reactor is able to produce radical concentrations of ca. 8 1011 cm
3 for OH, 3 106 cm3 for O(1D), 3.3 1010 cm3 for O(3P) and 1.6 1012 cm3 for Cl. The reactor can be
operated at pressures from 103 to 103 mbar and temperatures from 240 to 330 K. As a test of the system
we have studied the reaction CHCl3 þ Cl using the relative rate technique and find kCHCl3þCl/
kCH4þCl ¼ 1.03 0.11, in good agreement with the accepted value.