FT‐IR Imaging in ATR and Transmission Modes: Practical Considerations and Emerging Applications

A range of approaches and applications of Fourier transform infrared (FT‐IR) imaging have been developed in both attenuated total reflection (ATR) and transmission modes for a broad range of materials and chemical systems. This chapter describes some general principles and applications of FT‐IR imaging in ATR and transmission mode with a focus on technical considerations, new developments, and emerging applications. It discusses the advantages and limitations of the two imaging approaches (transmission and ATR) in terms of spatial resolution, image field of view (FOV), and possible artifacts. The chapter also discusses the novel developments including a new diamond ATR accessory specifically designed for imaging applications, an inverted‐prism expanded FOV (ZnSe) ATR accessory with expanding lenses, ATR imaging with variable angles of incidence ATR accessory. The different FOVs and spatial resolutions of different ATR accessories are also summarized and described in the chapter.