School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.
J Phys Chem A. 2010 Jul 8;114(26):7077-84. doi: 10.1021/jp103246t.
We consider the impact of uncertainties in the refractive index and size of polystyrene beads on the retrieved optical properties of aerosol particles by aerosol cavity ring down spectroscopy (A-CRDS). Polystyrene beads are frequently used to verify and calibrate light extinction measurements by cavity ring down instruments. Any uncertainties in either the polymer particle size or the refractive index can contribute to systematic errors in properties retrieved for any subsequent measurements on other aerosol types. We demonstrate that the tolerances on bead size reported by the manufacturers can lead to a range in the real part of the refractive index of the polymer beads retrieved from A-CRDS measurements of as large as 2.9%. Further, we show that the current uncertainty in the refractive index of polystyrene beads in the visible part of the electromagnetic spectrum limits the accuracy with which the real part of the refractive index of other aerosol types can be retrieved to uncertainties of -0.5% and +0.3% at a minimum. This error should be included in any subsequent retrieval of aerosol optical properties from aerosol cavity ring down instruments that are dependent on polystyrene bead calibration. It is expected that such calibrations could lead to significantly larger uncertainties if the complex part of the refractive index is to be retrieved.
我们考虑了聚苯乙烯珠粒的折射率和尺寸的不确定性对气溶胶腔衰荡光谱（A-CRDS）反演气溶胶粒子光学性质的影响。聚苯乙烯珠粒常用于验证和校准腔衰荡仪器的光消光测量。聚合物颗粒尺寸或折射率的任何不确定性都会导致对任何后续气溶胶类型测量的反演性质产生系统误差。我们证明，制造商报告的珠粒尺寸容差可能导致 A-CRDS 测量中反演的聚合物珠粒真实折射率的范围高达 2.9%。此外，我们表明，目前在电磁光谱可见光部分的聚苯乙烯珠粒的折射率不确定度限制了从气溶胶腔衰荡仪器反演其他气溶胶类型真实折射率的精度，最小不确定度为-0.5%和+0.3%。如果依赖于聚苯乙烯珠粒校准，从气溶胶腔衰荡仪器反演气溶胶光学性质时，应包括此误差。如果要反演折射率的复数部分，则此类校准预计会导致更大的不确定性。
