The rotational constant for CO in the ground and the first excited vibrational states are 1.9 and $1.6\,\mathrm{cm^{-1}}$, respectively. The % change in the internuclear distance due to vibrational excitation is
(a)9
(b)30
(c)16
(d)0
Answer
Answer: A ✓ checked by 4AB · confidence high
The source book printed no answer; this one was worked out and checked — see the explanation.
Explanation
B ∝ 1/r²: r₁/r₀ = √(B₀/B₁) = √(1.9/1.6) = 1.09, a 9 % increase in bond length on vibrational excitation.