Hyperspectral and time-resolved IR laser polarimetry

Contactless and destruction-free polarimetric IR methods allow for structural and chemical thin-film analyses in catalysis, environmental, biomedical, material and space applications. The adaption of pulsed brilliant light sources can provide high spatial and temporal resolution. Usage of a handy IR laser (e.g., a quantum cascade laser, QCL) in combination with a single-shot measurement scheme enables new polarimetric applications in laboratory and field analysis as well as industrial process control. With such single-shot IR laser spectroscopies, the limits of classical FTIR techniques can be overcome, making available new measurement opportunities that offer short acquisition times at high optical throughputs and high spectral resolutions. Notably, hyperspectral IR laser ellipsometry can measure time-dependent phase and amplitude images in the minute range but can also perform selected single measurements from the μs scale upwards. In this work, we introduce possibilities for the study of solid–liquid interfaces, starting with an example performed with classical FTIR ellipsometry; then we display the advantages of IR laser polarimetry in hyperspectral studies of the solid–liquid phase transition of a myristic acid film, and finally discuss future applications.