- #1
fsonnichsen
- 62
- 5
I have read from time to time (e.g. Lakowicz) that the fluorescence spectrum of a substance is not generally influenced by the wavelength excitation source. On the other had there is a correlation as exemplified in excitation-emission matrix spectra for example.
The obvious case is for fluorescence at wavelengths higher that the excitation. Omitting Raman phenomenon this should not happen-the excitation cannot promote electrons at an energy higher than the stimulus.
For excitation wavelengths greater than the energy levels of an atom, I would not expect much correlation-the energy can overcome the promotion barrier, the electron moves to the higher state, and fluorescence ensues. That said, clearly fluorescence analysis is done using the excitation correlation as a parameter so there must be a strong effect.
Does anyone know of an elaboration on this process? I have a few texts (Ingle) and articles here but little is said. The interactions with vibrational/rotational modes, analyte and solvent etc clearly play into this and I expect this is where the conversation begins.
Thanks
Fritz
The obvious case is for fluorescence at wavelengths higher that the excitation. Omitting Raman phenomenon this should not happen-the excitation cannot promote electrons at an energy higher than the stimulus.
For excitation wavelengths greater than the energy levels of an atom, I would not expect much correlation-the energy can overcome the promotion barrier, the electron moves to the higher state, and fluorescence ensues. That said, clearly fluorescence analysis is done using the excitation correlation as a parameter so there must be a strong effect.
Does anyone know of an elaboration on this process? I have a few texts (Ingle) and articles here but little is said. The interactions with vibrational/rotational modes, analyte and solvent etc clearly play into this and I expect this is where the conversation begins.
Thanks
Fritz