If the bond length of a heteronuclear diatomic molecule is greater in the upper vibrational state, the gap between the successive absorption lines of P-branch
(a)Increases non-linearly
(b)Decreases non-linearly
(c)Increases linearly
(d)Decreases linearly
Answer
Answer: A ✓ checked by 4AB · confidence medium
Explanation
A longer bond in v = 1 means B₁ < B₀; the P-branch spacing 2B₀ + 2(B₁ − B₀)... grows with J through the (B₁ − B₀)J² term, so the gaps increase non-linearly.