3.3 The equilibrium vibration frequency of the iodine molecule 12 is 215 cm-', and the anharmonicity constant x is 0.003; what, at 300 K, is the intensity of the 'hot band' (u=1=2 transition) relative to that of the fundamental (v=0v=1)? 34 An infra-red spectrum of OCS is obtained in which the rotational fine structure is not resolved. Using data from Table 2.2, calculate the separation between the P and R branch maxima at T = 300 K. 3.5 How many normal modes of vibration are possible for the following molecules: HBr, O2, OCS (linear), SO₂ (bent), BC, HC CH, CH4 CH3I, C6H6? 3.6 Estimate, using data from Table 3.4, the vibrational wavenumber of (a) CD, (b) -OD, (c) C-S-. (Relative atomic masses are: H 1, D2, C12, O=16, S = 32.) 3.7 The vibration frequency of 'HCl is 2990.6 cm; without calculating the bond force constant, estimate the frequency for 'H37CI, 2D3Cl, and 2D37Cl.