Abstract：
We developed a single-particle optical particle counter with polarization detection (SOPC) for the real-time measurement of the optical size and depolarization ratio (defined as the ratio of the vertical component to the parallel component of backward scattering) of atmospheric particles, the polarization ratio (DR) value can reflect the irregularity of the particles. The SOPC can detect aerosol particles with size larger than 500 nm and the maximum particle count rate reaches ∼1.8 × 105 particles per liter. The SOPC uses a modulated polarization laser to measure the optical size of particles according to forward scattering signal and the DR value of the particles by backward S and P signal components. The sampling rate of the SOPC was 106 #/(sec·channel), and all the raw data were processed online. The calibration curve was obtained by polystyrene latex spheres with sizes of 0.5-10 µm, and the average relative deviation of measurement was 3.96% for sub 3 µm particles. T-matrix method calculations showed that the DR value of backscatter light at 120° could describe the variations in the aspect ratio of particles in the above size range. We performed insitu observations for the evaluation of the SOPC, the mass concentration constructed by the SOPC showed good agreement with the PM2.5 measurements in a nearby state-controlled monitoring site. This instrument could provide useful data for source appointment and regulations against air pollution.
摘要：
我们开发了一种带有偏振检测（SOPC）的单粒子光学粒子计数器，用于实时测量大气粒子的光学尺寸和去偏振比（定义为向后散射的垂直分量与平行分量之比），极化比(DR)值可以反映颗粒的不规则性。SOPC可以检测尺寸大于500nm的气溶胶颗粒，最大颗粒计数率达到约1.8×105颗粒/升。SOPC使用调制偏振激光根据前向散射信号和由后向S和P信号分量的颗粒DR值测量颗粒的光学尺寸。SOPC的采样率为106#/(sec·channel),所有的原始数据都是在线处理的。校准曲线是通过尺寸为0.5-10μm的聚苯乙烯乳胶球获得的，亚3μm颗粒的平均测量相对偏差为3.96%。T矩阵法计算表明，背向散射光在120°处的DR值可以描述上述尺寸范围内颗粒纵横比的变化。我们对SOPC进行了原位观察，SOPC构建的质量浓度与附近国家控制的监测站点的PM2.5测量值吻合良好。该工具可以为来源指定和防止空气污染的法规提供有用的数据。
