Institute for Atmospheric and Environmental Sciences, Goethe-University Frankfurt am Main, Altenhöferallee 1, 60438 Frankfurt am Main, Germany.
J Phys Chem A. 2012 Jun 21;116(24):6375-86. doi: 10.1021/jp212123n. Epub 2012 Mar 14.
The accurate measurement of the gaseous sulfuric acid concentration is crucial within many fields of atmospheric science. Instruments utilizing chemical ionization mass spectrometry (CIMS) measuring H(2)SO(4), therefore, require a careful calibration. We have set up a calibration source that can provide a stable and adjustable concentration of H(2)SO(4). The calibration system initiates the production of sulfuric acid through the oxidation of SO(2) by OH. The hydroxyl radical is produced by UV photolysis of water vapor. A numerical model calculates the H(2)SO(4) concentration provided at the outlet of the calibration source. From comparison of this concentration and the signals measured by CIMS, a calibration factor is derived. This factor is evaluated to be 1.1 × 10(10) cm(-3), which is in good agreement with values found in the literature for other CIMS instruments measuring H(2)SO(4). The calibration system is described in detail and the results are discussed. Because the setup is external to the CIMS instrument, it offers the possibility for future CIMS intercomparison measurements by providing defined and stable concentrations of sulfuric acid.
在许多大气科学领域，准确测量气态硫酸浓度至关重要。因此，利用化学电离质谱（CIMS）测量 H(2)SO(4)的仪器需要仔细校准。我们已经建立了一个校准源，可以提供稳定且可调的 H(2)SO(4)浓度。校准系统通过 OH 氧化 SO(2)来引发硫酸的产生。羟基自由基通过水蒸气的紫外线光解产生。数值模型计算校准源出口处提供的 H(2)SO(4)浓度。通过比较该浓度和 CIMS 测量的信号，得出校准因子。该因子评估为 1.1×10(10)cm(-3)，与其他用于测量 H(2)SO(4)的 CIMS 仪器的文献值非常吻合。详细描述了校准系统，并讨论了结果。由于该设置在 CIMS 仪器外部，因此通过提供定义和稳定的硫酸浓度，为未来的 CIMS 相互比较测量提供了可能性。
