<p>In situ measurements of
the chemical compositions and mechanical properties of kerogen help understand
the formation, transformation, and utilization of organic matter in the oil
shale at the nanoscale. However, the optical diffraction limit prevents attainment
of nanoscale resolution using conventional spectroscopy and microscopy. Here, we
utilize peak force infrared (PFIR) microscopy for multimodal characterization
of kerogen in oil shale. The PFIR provides correlative infrared imaging, mechanical
mapping, and broadband infrared spectroscopy capability with 6 nm spatial
resolution. We observed nanoscale heterogeneity in the chemical composition,
aromaticity, and maturity of the kerogens from oil shales from Eagle Ford shale
play in Texas. The kerogen aromaticity positively correlates with
the local mechanical moduli of the surrounding inorganic matrix, manifesting
the Le Chatelier’s principle. In situ spectro-mechanical characterization of oil
shale will yield valuable insight for geochemical and geomechanical modeling on
the origin and transformation of kerogen in the oil shale.</p>