“…The band at 960 cm À1 is assigned to n 1 (A 1 ), the bands around 426 cm À1 and 443 cm À1 are characteristic of n 2 (E 2 ) [17]. These four vibrations are denoted as n 1 (A 1 ), n 2 (E 2 ), n 3 (F 2 ) and n 4 (F 2 ), respectively, and are all Raman active.…”