This paper summarizes the progress achieved over the past fifteen years in applying vibrational (Raman and IR) spectroscopy to problems of medical diagnostics and cellular biology. During this time, a number of research groups have verified the enormous information content of vibrational spectra; in fact, genomic, proteomic, and metabolomic information can be deduced by decoding the observed vibrational spectra. This decoding process is aided enormously by the availability of high-power computer workstations and advanced algorithms for data analysis. Furthermore, commercial instrumentation for the fast collection of both Raman and infrared microspectral data has rendered practical the collection of images based solely on spectral data. The progress in the field has been manifested by a steady increase in the number and quality of publications submitted by established and new research groups in vibrational biological and biomedical arenas.

The time‐dependent IR spectra during dehydration of fully hydrated Nafion show the reversible disappearance of the 1061 cm−1 and 969 cm−1 concurrent with the emergence of peaks at ∼928 cm−1 and ∼1408 cm−1. The first pair of group modes is associated with a dissociated exchange group (sulfonate) with a local C3V symmetry. The C3V group modes shift with state‐of‐hydration: The 969 cm−1 peak completely vanishes and the 1061 cm−1 is reduced to a small shoulder at 1070 cm−1 at end of dehydration. The C3V group modes are replaced by the pair of group modes of an associated exchange group (sulfonic acid) with C1 local symmetry. The density functional theory normal mode analysis confirms that the sulfonic acid/sulfonate site plays a dominant role in the C1 and C3V group modes, respectively. This work clarifies the importance of assigning fluoropolymers peaks as group modes rather than traditional single functional group assignments as is often the case with the ∼1061 cm−1 and ∼969 cm−1 C3V group modes. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1329–1334

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The dehydration of SPEEK-[H] (protonated sulfonated poly(ether ether ketone)) converts 3-fold symmetric (C 3V) hydrated sulfonate sites to sulfonic acid sites with no local symmetry (C 1). Like Nafion-[H], SPEEK-[H] C 3V and C 1 environments afford IR group modes (C 3V,HF (1087 cm-1); C 3V,LF (1026 cm-1) and C 1,HF (1362 cm-1); C 1,LF (904 cm-1)) due to the mechanical coupling of vibrational internal coordinates of an ether link with those of the sulfonate or sulfonic acid exchange site. C 3V and C 1 bands are inversely correlated during membrane hydration/dehydration. Hydrated SPEEK-[M] (M: Cu 2+ , Ni 2+ , Cd 2+ , Pb 2+ , Sr 2+ or Ba 2+) exhibits SPEEK-[H] C 3V bands because cation waters of hydration preclude binding to the hydrated exchange site. When cation hydration spheres are thermally stripped at high vacuum, SPEEK-[M] C 3V bands supplant SPEEK-[H] C 3V bands, inducing SPEEK cross-linking. Incomplete cross-linking is evidenced by low intensities of SPEEK-[M] C 1,HF bands. The 1362 cm-1 band intensities are inversely correlated with cation hydration enthalpies.