Abstract. Chemical characterization of organic coatings is important to advance our understanding of the physio-chemical properties and environmental fate of black carbon (BC) particles. The soot-particle aerosol mass spectrometer (SP-AMS) has been utilized for this purpose in recent field studies. The laser vaporization (LV) scheme of SP-AMS can heat BC cores gradually until they are completely vaporized, during which organic coatings can be vaporized at temperatures lower than that of the thermal vaporizer (TV) used in a standard high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) that employs flash vaporization. This work investigates the effects of vaporization schemes on fragmentation and elemental analysis of known oxygenated organic species using three SP-AMS instruments. We show that LV can reduce fragmentation of organic molecules. Substantial enhancement of C2H3O⁺/CO2⁺ and C2H4O2⁺ signals was observed for most of the tested species when the LV scheme was used, suggesting that the observational frameworks based using HR-ToF-AMS field data may not be directly applicable for evaluating the chemical evolution of oxygenated organic aerosol (OOA) components coated on ambient BC particles. The uncertainties of H:C and O:C determined by the improved-ambient (I-A) method for both LV and TV approaches were similar, with scaling factors of 1.10 for H:C and 0.89 for O:C were determined to facilitate more direct comparisons between observations from the two vaporization schemes. Furthermore, the I-A method was updated based on the multilinear regression model for the LV scheme measurements. The updated parameters can reduce the relative errors of O:C from −26.3 % to 5.8 %, whereas the relative errors of H:C remain roughly the same. Applying the scaling factors and the updated parameters for the I-A method to ambient data, we found that even though the time series of OOA components determined by the LV and TV schemes are strongly correlated at the same location, OOA coatings were likely less oxygenated compared to those externally mixed with BC.

中文翻译：

---

烟尘颗粒气溶胶质谱仪对黑碳颗粒上的氧化有机涂层进行元素分析

摘要。有机涂层的化学表征对于增进我们对黑碳（BC）颗粒的理化性质和环境命运的理解至关重要。烟尘颗粒气溶胶质谱仪（SP-AMS）已在最近的现场研究中用于此目的。SP-AMS的激光汽化（LV）方案可以逐步加热BC磁芯，直到其完全汽化，在此期间，有机涂层可以在低于标准高分辨率时间段中使用的热汽化器（TV）的温度下汽化。飞行中的气溶胶质谱仪（HR-ToF-AMS），采用了闪蒸技术。这项工作使用三种SP-AMS仪器研究了汽化方案对已知含氧有机物的裂解和元素分析的影响。我们表明，LV可以减少有机分子的碎片。大量增强C2H3O⁺ / CO2 ⁺和C2H4O2 ⁺当使用LV方案时，对于大多数被测物种都观察到信号，这表明基于HR-ToF-AMS现场数据的观测框架可能不直接适用于评估涂在表面的含氧有机气溶胶（OOA）组分的化学演化。环境BC粒子。LV和TV方法的改进环境（IA）方法确定的H：C和O：C的不确定度相似，确定H：C的比例因子为1.10，O：C的比例因子为0.89，以促进更直接两种蒸发方案的观测值之间的比较。此外，基于多线性回归模型的LV方案测量，更新了IA方法。更新的参数可以将O：C的相对误差从−26.3％降低到5.8％，而H：C的相对误差则保持大致相同。