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@ARTICLE{Fuchs:15753,
      author       = {Fuchs, H. and Bohn, B. and Hofzumahaus, A. and Holland, F.
                      and Lu, K.D. and Nehr, S. and Rohrer, F. and Wahner, A.},
      title        = {{D}etection of {HO}2 by laser-induced fluorescence:
                      calibration and interferences from {RO}2 radicals},
      journal      = {Atmospheric measurement techniques},
      volume       = {4},
      issn         = {1867-1381},
      address      = {Katlenburg-Lindau},
      publisher    = {Copernicus},
      reportid     = {PreJuSER-15753},
      pages        = {1209 - 1225},
      year         = {2011},
      note         = {Record converted from VDB: 12.11.2012},
      abstract     = {HO2 concentration measurements are widely accomplished by
                      chemical conversion of HO2 to OH including reaction with NO
                      and subsequent detection of OH by laser-induced
                      fluorescence. RO2 radicals can be converted to OH via a
                      similar radical reaction sequence including reaction with
                      NO, so that they are potential interferences for HO2
                      measurements. Here, the conversion efficiency of various RO2
                      species to HO2 is investigated. Experiments were conducted
                      with a radical source that produces OH and HO2 by water
                      photolysis at 185 nm, which is frequently used for
                      calibration of LIF instruments. The ratio of HO2 and the sum
                      of OH and HO2 concentrations provided by the radical source
                      was investigated and was found to be 0.50 +/- 0.02. RO2
                      radicals are produced by the reaction of various organic
                      compounds with OH in the radical source. Interferences via
                      chemical conversion from RO2 radicals produced by the
                      reaction of OH with methane and ethane (H-atom abstraction)
                      are negligible consistent with measurements in the past.
                      However, RO2 radicals from OH plus alkene- and
                      aromatic-precursors including isoprene (mainly OH-addition)
                      are detected with a relative sensitivity larger than $80\%$
                      with respect to that for HO2 for the configuration of the
                      instrument with which it was operated during field
                      campaigns. Also RO2 from OH plus methyl vinyl ketone and
                      methacrolein exhibit a relative detection sensitivity of 60
                      $\%.$ Thus, previous measurements of HO2 radical
                      concentrations with this instrument were biased in the
                      presence of high RO2 radical concentrations from isoprene,
                      alkenes or aromatics, but were not affected by interferences
                      in remote clean environment with no significant emissions of
                      biogenic VOCs, when the OH reactivity was dominated by small
                      alkanes. By reducing the NO concentration and/or the
                      transport time between NO addition and OH detection,
                      interference from these RO2 species are suppressed to values
                      below $20\%$ relative to the HO2 detection sensitivity. The
                      HO2 conversion efficiency is also smaller by a factor of
                      four, but this is still sufficient for atmospheric HO2
                      concentration measurements for a wide range of conditions.},
      keywords     = {J (WoSType)},
      cin          = {IEK-8},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-8-20101013},
      pnm          = {Atmosphäre und Klima},
      pid          = {G:(DE-Juel1)FUEK491},
      shelfmark    = {Meteorology $\&$ Atmospheric Sciences},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000292248700003},
      doi          = {10.5194/amt-4-1209-2011},
      url          = {https://juser.fz-juelich.de/record/15753},
}