Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary AB T2N 1N4, Canada.
Anal Chem. 2010 Aug 1;82(15):6695-703. doi: 10.1021/ac101441z.
Peroxycarboxylic nitric anhydrides (PANs) have long been recognized as important trace gas constituents of the troposphere. Here, we describe a blue diode laser thermal dissociation cavity ring-down spectrometer for rapid and absolute measurements of total peroxyacyl nitrate (SigmaPAN) abundances at ambient concentration levels. The PANs are thermally dissociated and detected as NO2, whose mixing ratios are quantified by optical absorption at 405 nm relative to a reference channel kept at ambient temperature. The effective NO2 absorption cross-section at the diode laser emission wavelength was measured to be 6.1 x 10(-19) cm2 molecule(-1), in excellent agreement with a prediction based on a projection of a high-resolution literature absorption spectrum onto the laser line width. The performance, i.e., accuracy and precision of measurement and matrix effects, of the new 405 nm thermal dissociation cavity ring-down spectrometer was evaluated and compared to that of a 532 nm thermal dissociation cavity ring-down spectrometer using laboratory-generated air samples. The new 405 nm spectrometer was considerably more sensitive and compact than the previously constructed version. The key advantage of laser thermal dissociation cavity ring-down spectroscopy is that the measurement can be considered absolute and does not need to rely on external calibration.
过氧羧酸硝酸酯（PANs）长期以来一直被认为是对流层中重要的痕量气体成分。在这里，我们描述了一种用于快速和绝对测量环境浓度水平下总过氧酰基硝酸盐（SigmaPAN）丰度的蓝色二极管激光热解离腔衰减光谱仪。PANs 被热解离并检测为 NO2，其混合比通过相对于保持在环境温度的参考通道在 405nm 处的光吸收来定量。在二极管激光发射波长处测量到有效 NO2 吸收截面为 6.1 x 10(-19) cm2 分子(-1)，与基于高分辨率文献吸收光谱投影到激光线宽的预测非常吻合。使用实验室产生的空气样品评估了新的 405nm 热解离腔衰减光谱仪的性能，即测量的准确性和精密度以及基质效应，并与 532nm 热解离腔衰减光谱仪进行了比较。新的 405nm 光谱仪比以前构建的版本灵敏得多，而且更紧凑。激光热解离腔衰减光谱学的主要优势在于测量可以被认为是绝对的，不需要依赖外部校准。
