Raman Spectroscopy of Rhombohedral P₄O₁₀

A complete Raman vibrational analysis has been performed on phase-pure rhombohedral phosphorus pentoxide (P 4 O 10 ) at room temperature. The “molecular” T d symmetry is reduced to C 3 v symmetry when bound in the rhombohedral crystalline lattice. Therefore, the 15 fundamental modes of vibration irreducibly represented as Γ vib = 3A 1 + 3E + 3T 1 + 6T 2 reduce to 21 fundamental modes with a factor group analysis resulting in Γ vib = 9A 1 + 12E for the irreducible representation, all of which are Raman active. Complete vibrational assignments and relative intensities, including all T 2 to E and A 1 splittings, are reported. Five new E fundamentals (262, 329, 419, 829, and 846 cm -1 ) in the C 3 v symmetry were observed. All peaks show good agreement with theoretical calculations.