使用粒径测量的方法,对气溶胶颗粒密度进行探索研究。利用静电分级器(DMA)选出不同迁 移粒径的单分散气溶胶颗粒;将所得的颗粒通入气溶胶飞行时间质谱仪(ATOFMS), 根据双光束粒径测量区的 飞行时间测定单颗粒对应的空气动力学粒径；由迁移粒径和空气动力学粒径间的定量关系得到球形 颗粒密度或者非球形颗粒的有效密度。在对已知化学成分和密度的邻苯二甲酸二辛酯(DOP)气溶胶颗 粒进行标定实验后,运用该方法对非球形的硫酸铵、氯化钠、硝酸铵颗粒进行测量,有效密度测量结果分别为1.211 g/cm3、 1.333 g/cm3、1.039 g/cm3; 球形的橄榄油颗粒密度测量结果为0.914 g/cm3。

The density of aerosol particles was explored by using particles size measurement. A differential mobility analyzer (DMA) was used to select a monodisperse particle population with specific mobility diameter. The monodisperse particles beam enter aerosol time-of-flight mass spectrometer (ATOFMS). According to the time of flights between the two optical detection stages individual particle vacuum aerodynamic diameter was measured. Together with the mobility and aerodynamic diameters the quantitative relationship between them was yielded. Then the particle density for spherical, ρp, or particle effective density for aspherical, ρeff, was obtained. A calibration experiment was carried out by using dioctyl phthalate (DOP), with known chemical composition and density, on the system. Then the system was used to measure the particle effective densities of ammonium sulfate, sodium chloride, ammonium nitrate. The results are 1.211 g/cm3, 1.333 g/cm3, 1.039 g/cm3, respectively. The particle density for spherical olive oil is 0.914 g/cm3.