The following data is obtained for a light diatomic (AB) molecule from its rotational Raman spectrum. $\left(\mathrm{B}=2 \mathrm{cm}^{-1} ; \mathrm{x}_{\mathrm{e}}=0.01 ; \overline{\mathrm{v}}_{\mathrm{e}}=1600 \mathrm{cm}^{-1}\right)$ If the molecule is irradiated by a laser of $20,000 \mathrm{cm}^{-1}$, the expected Stokes lines (in $c m-1$ ) for this molecule are
(a)18348, 18356, 18368, 18380, 18388
(b)18412, 18420, 18432, 18444, 18452
(c)18380, 18388, 18400, 18412, 18420
(d)18416, 18424, 18430, 18440, 18452
Answer
Answer: B ✓ checked by 4AB · confidence high
Explanation
The vibrational Raman band centre is 20 000 − 1600(1 − 2x_e) = 20 000 − 1568 = 18 432 cm⁻¹. The O and S branch lines sit at ±6B and ±10B (12, 20 cm⁻¹): 18412, 18420, 18432, 18444, 18452 (b).