Fig. 4.

Raman difference spectra of HDV crystals [HDV + 20 mM Mg²⁺] minus [HDV no Mg²⁺] pH 6.0. Vertical bar represents photon events. (a) Partial Raman spectrum showing PO₂⁻ symmetric stretch of phosphate groups bound innersphere to Mg²⁺ at 1117 cm⁻¹; the negative differential at 1100 cm⁻¹ is due to phosphate symmetric stretch of metal-free groups. (b) Raman signatures of Mg hydrate (pentahydrate and tetrahydrate are both possible) bound innersphere to PO₂⁻ oxygen. Adapted with permission from [25]. (Copyright, American Chemical Society.)