A UV-Vis photoacoustic spectrophotometer.
A UV-Vis photoacoustic spectrophotometer.
复制标题
紫外-可见光声分光光度计。
DOI：
10.1021/ac501196u
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发表时间：
2014
影响因子：
7.4
通讯作者：
Geoffrey D Smith
中科院分区：
文献类型：
--
作者：
Joseph R. Wiegand;L. Mathews;Geoffrey D Smith
介绍了一种新型光声分光光度计(PAS)，用于测量紫外可见光谱范围内的气相和气溶胶吸收。来自宽带汞弧灯的光通过带通干涉滤光片(以301 nm、314 nm、364 nm、405 nm、436 nm、546 nm、578和687 nm为中心)在300到700 nm的8个不同波段中过滤，并在进入光声电池之前用光斩波器进行调制。除较低强度的687 nm波段的检测下限为10.2 mm(-1)外，所有波长波段的20-S检测下限均优于3.0 mm(-1)。对几个波长的气相丙酮和黑松香气溶胶吸收截面的验证测量表明，与先前测量的(丙酮)和Mie理论(黑松)预测的结果在10%以内一致。使用PAS仪器测量了环境气溶胶的紫外-可见吸收光谱，结果表明，在紫外区有显著的增加，吸收从405 nm增加到301 nm，增加了300%。这种类型的测量覆盖了整个UV-可见区域，并且没有与基于滤光片的方法相关的伪影，这是以前不可能的，我们展示了它对不同类型的光吸收环境颗粒进行分类和量化的前景。
A novel photoacoustic spectrophotometer (PAS) for the measurement of gas-phase and aerosol absorption over the UV-visible region of the spectrum is described. Light from a broadband Hg arc lamp is filtered in eight separate bands from 300 to 700 nm using bandpass interference filters (centered at 301 nm, 314 nm, 364 nm, 405 nm, 436 nm, 546 nm, 578 and 687 nm) and modulated with an optical chopper before entering the photoacoustic cell. All wavelength bands feature a 20-s detection limit of better than 3.0 Mm(-1) with the exception of the lower-intensity 687 nm band for which it is 10.2 Mm(-1). Validation measurements of gas-phase acetone and nigrosin aerosol absorption cross sections at several wavelengths demonstrate agreement to within 10% with those measured previously (for acetone) and those predicted by Mie theory (for nigrosin). The PAS instrument is used to measure the UV-visible absorption spectrum of ambient aerosol demonstrating a dramatic increase in the UV region with absorption increasing by 300% from 405 to 301 nm. This type of measurement throughout the UV-visible region and free from artifacts associated with filter-based methods has not been possible previously, and we demonstrate its promise for classifying and quantifying different types of light-absorbing ambient particles.