- #1
DanAbnormal
- 23
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Can anybody tell me the significance of the band origin for a P(Q)R structure in the ultraviolet region of a molecules spectrum?
In standard vibrational spectra, I understand that its roughly the harmonic frequency of the oscillator, and that the rotational constant can also be found from separations.
Now say I am looking at vibration-rotation transitions between the ground state and the excited state. What is the significance of the band origin and rotational constant?
If the internuclear separations of the ground state and excited state are equal, then the spectral structure should be like that for ordinary vib-rotational spectra, is that right? Therefore the ground state and first excited states have the same rotational constant B (becuase it depends on R, internuclear distance) but what doe the band origin signify, because obviously its positioned somewhere in the UV, whereas the band origin for normal vibration spectra is centred in the infrared...
Can someone enlighten me please?!
Cheers
In standard vibrational spectra, I understand that its roughly the harmonic frequency of the oscillator, and that the rotational constant can also be found from separations.
Now say I am looking at vibration-rotation transitions between the ground state and the excited state. What is the significance of the band origin and rotational constant?
If the internuclear separations of the ground state and excited state are equal, then the spectral structure should be like that for ordinary vib-rotational spectra, is that right? Therefore the ground state and first excited states have the same rotational constant B (becuase it depends on R, internuclear distance) but what doe the band origin signify, because obviously its positioned somewhere in the UV, whereas the band origin for normal vibration spectra is centred in the infrared...
Can someone enlighten me please?!
Cheers