The aggregation of dihydrogen phosphate ion has been studied by Raman spectroscopy during serial dilution of highly concentrated (>5 M) solutions. Factor analysis has been used to recover monomer and aggregate spectra from families of 600–2000 spectra obtained during dilution to about 0.1 M. Spectra of the free aquated dihydrogen phosphate ion and its dimer, trimer, and tetramer have been obtained. There is some evidence for the existence of longer chain aggregates. The serial dilution procedure has been verified by dilution of 2.3 M glycine solution. Only spectra of monomer and dimer ions are recovered. For the well-understood glycine system, the band positions and intensities and the dimerization concentration-dependence are in agreement with previously reported values.

The crystallinity of syndiotactic polystyrene (sPS) is studied by hyperspectral Raman line imaging. Images of a 140 × 1200 μm region of an sPS test piece containing 39 200 pixels/image were generated from spectra taken over the wavenumber interval between 300 and 875 cm−1. The spectral region includes the moderate-intensity crystallinity-sensitive bands in the 770 800 cm−1 region, as well as other useful but weaker marker bands. Factor analysis was used to extract structure information from the set of spectra. Four non-noise factors were extracted; two were assigned to crystalline and amorphous sPS and the other two to background. Score images of the crystalline and amorphous sPS factors were used to visualize distribution of those species. The results were compared to the integrated Raman intensity image for the 773 cm−1 band of crystalline sPS.

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