In situ detection of atomic and molecular iodine using resonance and off-resonance fluorescence by lamp excitation: ROFLEX

J. C. Gómez Martín, J. Blahins, U. Gross, T. Ingham, A. Goddard, A. S. Mahajan, A. Ubelis, A. Saiz-Lopez
2010 Atmospheric Measurement Techniques Discussions  
We demonstrate a new instrument for in situ detection of atmospheric iodine atoms and molecules based on atomic and molecular resonance and off-resonance ultraviolet fluorescence excited by lamp emission. The instrument combines the robustness, light weight, low power consumption and efficient excitation of radio-frequency discharge light sources with the high sensitivity of the photon counting technique. Calibration of I 2 fluorescence is achieved via quantitative detection of the molecule by
more » ... of the molecule by Incoherent Broad Band Cavity-enhanced Absorption Spectroscopy. Atomic iodine fluorescence signal is calibrated by controlled broad band photolysis of known I 2 concentrations in the visible spectral range at atmospheric pressure. The instrument has been optimised in laboratory experiments to reach detection limits of 1.2 pptv for I atoms and 13 pptv for I 2 , for S/N = 1 and 10 min of integration time. The ROFLEX system has been deployed in a field campaign in northern Spain, representing the first concurrent observation of ambient mixing ratios of iodine atoms and molecules in the 1-350 pptv range.
doi:10.5194/amtd-3-3803-2010 fatcat:pwbareo52bbgtnuzfyjx5hmkwy