Question

How does the changing wavelength affect the emission spectrum in fluorescence spectroscopy? How does this compare to UV‐Vis?

Answer 1

Increase in wavelength means a decrease in energy. If the excitation wavelength is increases, the molecules will not be excited to lower energy excited states. As a result, they will emit low energy low frequency light.

In UV-vis spectroscopy, the molecule absorbs at a perticular wavelength. The intensity of absorption depends on the concentration of the solution. So, even if you change the wavelength , the molecule will still absorb at the perticular wavelnght where it is suppose to do.