“…In the range 2700e3100 cm À1 , several weak lines (which correspond to overtones [9,20]) and four strong and broad bands at 2853, 2894, 2945 and 2968 cm À1 appear. The first corresponds to the first overtone of the normal mode 10E 1u (2 Â 1425 cm À1 ) and the latter to n s CH 3 , n as CH 3 and n as CH 3 , respectively.…”