适用于测量大气气溶胶吸收系数的光声光谱系统的研究

摘要

外部噪声和环境温湿度变化对光声池性能的影响是光声光谱技术在实际大气气溶胶吸收测量应用中遇到的主要问题.详细分析了环境温湿度变化引起的共振频率漂移对光声信号的影响,提出了抑制流动噪声和采样泵振动噪声的方法,研制完成了一套测量大气气溶胶吸收的光声光谱系统,探测极限为1.4×10-8w·cm-1·Hz-1/2.利用NO2气体在532 nm的吸收对光声池进行了标定,并对实际大气气溶胶的吸收特性进行了测量,结果表明光声光谱测量系统可以满足自然悬浮状态下的气溶胶吸收系数的实时测量.%In the present paper,the authors focus on the effect of the resonance frequency shift due to the changes in temperature and humidity on the PA signal,present several methods to control the noise derived form gas flow and vibration from the sam pling pump.Based on the efforts mentioned above,a detection limit of 1.4 × 10-8 W · cm-1 · Hz-1/2 was achieved for the meas urement of atmospheric aerosols absorption coefficient.During the experiments,the PA cell was calibrated with the absorption of standard NO2 gas at 532 nm and the atmospheric aerosols were measured continuously.The measurement results show tha the PAS is suitable for the real-time measurement of the absorption coefficient of atmospheric aerosols in their natural suspended state.