Simultaneous Optical Photothermal Infrared (O-PTIR) and Raman Spectroscopy of Submicrometer Atmospheric Particles
Simultaneous Optical Photothermal Infrared (O-PTIR) and Raman Spectroscopy of Submicrometer Atmospheric Particles
复制标题
DOI：
10.1017/s1431927620022679
复制
发表时间：
2020-06
影响因子：
2.8
通讯作者：
Nicole E. Olson;Yao Xiao;Ziying Lei;A. Ault
中科院分区：
文献类型：
--
作者：
Nicole E. Olson;Yao Xiao;Ziying Lei;A. Ault
对大气中含量最多的单个大气气溶胶进行物理化学分析（约10微米，与气溶胶健康和气候影响的相关性较小）。光学光热红外（O-PTIR）光谱是一种非接触式方法，其通过使用连续波可见激光（532 nm）的散射强度的变化来检测当振动模式被可调谐IR激光（QCL：800-1800 cm-1或OPO：2600-3600 cm-1）激发时的光热膨胀，从而规避衍射限制。本文中，我们通过还收集用于拉曼光谱的非弹性散射可见光子，在环境温度和压力下在单个点处同时收集空气动力学直径<400 nm（在撞击和扩散之前）的单个颗粒的O-PTIR光谱和拉曼光谱。收集具有不同基底、颗粒化学组成和形态（即，核-壳），以及具有亚微米空间分辨率的IR映射。环境大气颗粒物的初始O-PTIR分析确定了单个亚微米和超微米颗粒物中的无机和有机模式。本文所述的具有亚微米空间分辨率的同时IR和拉曼显微术在大气化学和许多其他领域（例如，材料和生物研究）。
Physicochemical analysis of individual atmospheric aerosols at the most abundant sizes in the atmosphere ( ~10 µm, which have less relevance to aerosol health and climate impacts. Optical photothermal infrared (O-PTIR) spectroscopy is a contactless method that circumvents diffraction limitations by using changes in the scattering intensity of a continuous wave visible laser (532 nm) to detect the photothermal expansion when a vibrational mode is excited by a tunable IR laser (QCL: 800-1800 cm-1 or OPO: 2600-3600 cm-1). Herein, we simultaneously collect O-PTIR spectra with Raman spectra at a single point for individual particles with aerodynamic diameters <400 nm (prior to impaction and spreading) at ambient temperature and pressure, by also collecting the inelastically scattered visible photons for Raman spectra. O-PTIR and Raman spectra were collected for submicrometer particles with different substrates, particle chemical compositions, and morphologies (i.e., core-shell), as well as IR mapping with submicron spatial resolution. Initial O-PTIR analysis of ambient atmospheric particles identified both inorganic and organic modes in individual sub- and super-micrometer particles. The simultaneous IR and Raman microscopy with submicron spatial resolution described herein has considerable potential both in atmospheric chemistry and numerous others fields (e.g., materials and biological research).