Hi all,
As far as I know, to distinguish the core-mechanism of UV-Vis spectrum and Raman spectrum, we can attach UV-Vis spectrum with Oscillation and Raman spectrum with Rovibronic State (Rotational - Vibrational - Electronic State) word.
However, I am having a vague distinction between Oscillation in the UV-Vis spectrum and Vibration in the Raman spectrum.
Can you clarify this for me?
I am not sure what you mean by "oscillation".
The core mechanism of UV-Vis absorbance is the induction of electric dipole transitions between the electronic states of an atom/molecule/solid by photons of appropriate energy/frequency. The selection rules include a change in dipole moment during the transition.
The core mechanism of Raman is inelastic scattering of photons by coupling to vibrations of bonds in a molecule/solid, or also rotations in the case of a molecule (although less commonly studied). The coupling causes transitions between vibrational/rotational states. The selection rules include a change in bond polarisability during the transition.
UV-Vis the energy is causing electrons to move between energy levels. The selection rules are complicated and not always observed in practice.
Raman is mainly studying changes in vibrational energy (like a normal IR spectrum would).
Oscillation?
UV-VIS absorption has nothing to do with this concept
It is the absorption of light by an electron going from the ground electronic state of an atom/molecule to a higher energy state, called excited state.
Superposed on this transition are changes in the vibrational state and rotational state
In small molecules in the gas-phase, specifically at low temperatures, all these transitions are resolved in an absorption spectrum
https://pubs.rsc.org/en/content/articlelanding/2021/CP/D0CP06170K#!divAbstract
FIG 3 provides this detail by zooming in
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