The use of Raman and infrared spectroscopy in determining the space symmetry group among the groups with the same rules of systematic absence in the diffraction patterns: Some basic principles and applications

Abstract

AbstractRaman spectroscopy and infrared (IR) spectroscopy can be used in the determination of the structural organization of crystals from the short‐range order (IR) to the mid‐ and far‐range orders (Raman). Among the 230 possible crystal space groups, only 61 can unambiguously be determined by X‐ray diffraction. In other cases, from two to five space groups are characterized by unified diffraction extinction rules. The symmetry of the active irreducible representations of vibrations in IR, Raman, and hyper‐Raman (HR) spectra for all crystallographic systems are systematized, and cases are indicated where the ambiguity in the assignment of crystal structures to the space groups with unified diffraction extinction rules can be overcome. The refinement of a space group of a mineral by analyzing the selection rules from IR and Raman spectra is discussed, and some examples are considered, including nontronite, kladnoite, and ugrandite.