Integrated Vibrational and X-Ray Spectroscopy in Cultural Heritage Materials: Recent Advances and Analytical Challenges.

This review presents recent advances in integrated vibrational and x-ray spectroscopic approaches for the characterization of cultural heritage materials. Vibrational techniques, including Raman, Fourier transform infrared (FT-IR), and optical photothermal infrared (O-PTIR) spectroscopy, together with x-ray fluorescence, diffraction, and absorption methods, provide complementary molecular, elemental, and structural information for the analysis of pigments, binders, and degradation products. Emphasis is placed on analytical capabilities, limitations, and the synergistic use of these techniques within multimodal workflows. Vibrational spectroscopy plays a central role in molecular identification and monitoring chemical transformations, whereas x-ray methods provide insight into elemental composition, crystallography, and pigment alteration mechanisms. Their integration establishes a robust framework for materials identification, stratigraphic interpretation, and investigation of degradation pathways in historical objects. Representative case studies discussed in this review illustrate how integrated vibrational and x-ray spectroscopic strategies address key analytical challenges in cultural heritage research, including the characterization of lead-based materials in works attributed to Leonardo da Vinci, compositional layering in paintings by Pablo Picasso, and cadmium yellow degradation in masterpieces by Edvard Munch and Vincent van Gogh. O-PTIR is highlighted as an emerging tool for submicron analysis, while combined Raman and X-Ray spectroscopic methods resolve environmentally driven pigment transformations. This review outlines current advances, practical challenges, and future directions in spectroscopy-driven research on complex materials.