Experimental Raman spectra analysis of selected PFAS compounds: Comparison with DFT predictions

Abstract

PFAS are persistent environmental pollutants with significant health implications, necessitating precise detection and characterization methods. This study employs Raman spectroscopy, supplemented by density functional theory (DFT) calculations, to investigate the vibrational spectroscopic properties of nine PFAS compounds with varying chain lengths and functional groups. Experimental Raman spectra revealed distinct vibrational peaks across low, medium, high, and ultra-high wavenumber regions, enabling differentiation based on molecular structure. DFT calculations provided detailed mode assignments and validated experimental observations, highlighting chain length and functional group-dependent spectral shifts. Additionally, using principal component analysis (PCA) and t-distributed stochastic neighbor embedding (t-SNE), the Raman spectra of 9 PFAS compounds can be clustered and separated well, revealing both structural similarities and unique functional group influences. The integration of experimental, computational, and data-driven methodologies demonstrates the potential of Raman spectroscopy as a robust tool for PFAS detection and differentiation. These findings enhance the spectral database for PFAS compounds and offer valuable insights for environmental monitoring and contamination analysis.

Keywords: Density function theory calculation; PCA and t-SNE; Perfluoroalkyl substances; Raman spectroscopy.