Pressure-induced phase transitions in crystalline l-serine studied by single-crystal and high-resolution powder X-ray diffraction

Pressure induces two isosymmetric reversible polymorphic transitions in l-serine related to a jumpwise change in the hydrogen bond networks and the conformation of the zwitter-ions. Single-crystal X-ray diffraction in situ allowed to find the structure of l-serine III at 8.0 GPa (the phase was previously reported based on Raman spectra [Kolesnik et al., Doklady Chem. 404 (2005) 169]). High-resolution X-ray powder diffraction data with a synchrotron radiation source suggest the formation of a superstructure with a and c parameters tripled as compared with the single-crystal model.