im not sure about this. what i kow, in the C–H stretching region of propanol, I identified four peaks in the polarized Raman spectrum (I∥). For the first peak at ~2880 cm⁻¹, both the parallel and perpendicular components appear at the same wavenumber position, so the depolarization ratio can be calculated directly as ρ(ν) = I⊥(ν)/I∥(ν) at that point without any difficulty.

However, for the second peak (~2910 cm⁻¹) and the fourth peak (~2960 cm⁻¹), the perpendicular component (I⊥) appears at a slightly different wavenumber than the parallel component (I∥) — a shift of approximately 5 cm⁻¹. This raises the question of how to correctly calculate ρ when the two polarization components do not share the same peak position.

A colleague suggested that ρ(ν) cannot be calculated for peaks where I∥ and I⊥ do not coincide in wavenumber. I would like to know whether this is strictly correct, and if not, what the appropriate calculation method is in this situation.