Question

a.) How many vibrational modes exist for CS2? Sketch these.

b.) How many unique (i.e., different) vibrational frequencies can be observed in CS2

c.) Which of the vibrational modes will show up in an infrared spectrum, and which in a Raman spectrum?

Answer 1

CS2 Carbon disulphide is a linear molecule, (linear) S-LES Total no. of vibreations - 30-5 - 3x3-5 = 4 Bending strekking Turusting sxc - s (symmetric Sixelching Berement) Sac S=C - s Wagging (a symmetric stretching (Molecular inbrations of CS2) CS2 has longer bonds and lower vibrational frequencies them ca Three characterised ubrahonal frequencies: 2 = 658 cm 4 Two bending Modes are degenerate 2 - 397 con D=1535cm? 23 Symmeteuk asymmetric stretching stretches D) bending,

of symmetry infrared inachine Rule of Mutual exclusion pounciple: If a molecule has centre then Ramen active modes are and vice-versa. IR LS2 Mods of rubl Raman Achio Inactive Inactive Irachines Active Sym stretchy Active Bend Acym strakly I