The vacuum ultraviolet beamline/endstations at NSRL dedicated to combustion research

An undulator-based vacuum ultraviolet (VUV) beamline (BL03U), intended for combustion chemistry studies, has been constructed at the National Synchrotron Radiation Laboratory (NSRL) in Hefei, China. The beamline is connected to the newly upgraded Hefei Light Source (HLS II), and could deliver photons in the 5-21 eV range, with a photon flux of 10¹³ photons s^-1 at 10 eV when the beam current is 300 mA. The monochromator of the beamline is equipped with two gratings (200 lines mm^-1 and 400 lines mm^-1) and its resolving power is 3900 at 7.3 eV for the 200 lines mm^-1 grating and 4200 at 14.6 eV for the 400 lines mm^-1 grating. The beamline serves three endstations which are designed for respective studies of premixed flame, fuel pyrolysis in flow reactor, and oxidation in jet-stirred reactor. Each endstation contains a reactor chamber, an ionization chamber where the molecular beam intersects with the VUV light, and a home-made reflectron time-of-flight mass spectrometer. The performance of the beamline and endstations with some preliminary results is presented here. The ability to detect reactive intermediates (e.g. H, O, OH and hydro­peroxides) is advantageous in combustion chemistry research.