Photothermal Polarimetric Nanoscopy: An Emerging Technique for Fingerprinting Minerals of Extraterrestrial Origin

Nanospectroscopic investigations of the mineralogical composition of materials returned via sample-return missions are crucial for our understanding of the origin and evolution of planetary objects in our Solar System. Here, we show that the emerging technique of photothermal polarimetric nanoscopy, a variant of atomic force microscopy-based infrared spectroscopy, enables one to derive infrared fingerprint spectra of minerals noninvasively on the nanoscale. Besides the spatially resolved identification of specific minerals and mineral phases, the evaluation of the polarization dependence of the photoinduced nanomechanical response, in combination with optical reference data, may allow the deduction of valuable structural information on individual nanocrystallites or grains embedded in solid matrices.