Dada Oluwatosin O, Bialkowski Stephen E
Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300, USA.
Appl Spectrosc. 2008 Dec;62(12):1336-43. doi: 10.1366/000370208786822340.
The potential of mid-infrared photothermal deflection spectrometry for aerosol analysis is demonstrated. Ammonium nitrate aerosols are deposited on a flat substrate using a micro-orifice uniform deposit impactor (MOUDI). Photothermal spectroscopy with optical beam deflection (mirage effect) is used to detect deposited aerosols. Photothermal deflection from aerosols is measured by using pulsed infrared laser light to heat up aerosols collected on the substrate. The deflection signal is obtained by measuring the position of a spot from a beam of light as it passes near the heated surface. The results indicate non-rotating impaction as the preferred MOUDI impaction method. Energy-dependent photothermal measurement shows a linear relationship between signal and laser intensity, and no loss of signal with time is observed. The detection limit from the signal-mass curve is 7.31 ng. For 30 minutes collection time and 30 L/min flow rate of the impactor, the limit of detection in terms of aerosol mass concentration is 0.65 microg m(-3).
展示了中红外光热偏转光谱法在气溶胶分析中的潜力。使用微孔均匀沉积冲击器（MOUDI）将硝酸铵气溶胶沉积在平坦的基底上。采用光束偏转光热光谱法（海市蜃楼效应）来检测沉积的气溶胶。通过使用脉冲红外激光加热收集在基底上的气溶胶来测量气溶胶的光热偏转。通过测量一束光在经过加热表面附近时光斑的位置来获得偏转信号。结果表明，非旋转撞击是首选的MOUDI撞击方法。能量相关的光热测量显示信号与激光强度之间呈线性关系，并且未观察到信号随时间的损失。根据信号-质量曲线得出的检测限为7.31 ng。对于30分钟的收集时间和冲击器30 L/min的流速，以气溶胶质量浓度计的检测限为0.65 μg m⁻³。
