Mid-IR HSI

External reflection IR spectroscopy is widely used in heritage science for the characterization and identification of organic and inorganic materials. As a vibrational molecular spectroscopic technique, it provides unique fingerprint ultimately aiding in the molecular identification of an unlimited variety of materials under examination. The mid-IR range is particularly well-suited for recognizing inorganic materials (with some limitations for metal oxides) as well as synthetic and natural organic materials. This technique can provide insights not only into the materials and painting techniques used but also into surface contaminants, alterations, and degradation products or processes. Mid-IR hyperspectral imaging enhances the highly diagnostic capabilities of external IR spectroscopy by transitioning from discrete single-point measurements to comprehensive hyperspectral imaging. Indeed the exploration of the mid-infrared spectral range (4000–800 cm⁻¹) delivers compositional images of great value for the understanding and preservation of artworks. Hyperspectral imaging in this spectral range is highly diagnostic, enabling not only the identification of pigments and their distribution but also revealing the nature and distribution of organic materials and degradation products. It basically works in external reflection mode, please refer to External reflection IR spectroscopy Methods for detail about this acquisition mode), even if possible unpredictable contribution from sample emission in the mid-IR cannot be excluded.

Fourier transform infrared spectroscopy

External reflection IR spectroscopy

Hyperspectral Imaging

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