Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Difference between an absorbance, emission, and excitation spectrum for uv-visible spectroscopy Ask Question.
Asked 7 years, 7 months ago. Active 6 months ago. Viewed 38k times. Improve this question. Safdar Faisal 6, 4 4 gold badges 19 19 silver badges 46 46 bronze badges. Add a comment. Active Oldest Votes. Improve this answer. There might be another peak in the absorbency spectrum that is greater, but you would have to have the spectrum to tell. Sign up or log in Sign up using Google. Sign up using Facebook. The wavelength of emission monochromator is set to a wavelength of known fluorescence emission by the sample, and the wavelength of the excitation monochromator is scanned across the desired excitation range and the intensity of fluorescence recorded on the detector as a function of excitation wavelength.
Excitation spectra can therefore be thought of as fluorescence detected absorption spectra. Figure 4: Schematic of the measurement of excitation spectra in a spectrofluorometer. Figure 5: Fluorescence emission spectrum of anthracene in cyclohexane measured using the FS5 Spectrofluorometer. Fluorescence emission spectra show the change in fluorescence intensity as a function of the wavelength of the emission light Figure 5 , and are measured using a spectrofluorometer.
The wavelength of excitation monochromator is set to a wavelength of known absorption by the sample, and the wavelength of the emission monochromator is scanned across the desired emission range and the intensity of the fluorescence recorded on the detector as a function of emission wavelength. Figure 6: Schematic of the measurement of emission spectra in a spectrofluorometer. For more information on the theory of absorption and fluorescence spectroscopy, please check out the frequently asked questions section on our blog.
What is Absorption 4. Excitation is the transfer of a system that is at a low energy state to a state of high energy. Thus, this term can be discussed regarding an electron bound to the nucleus at the ground state. Quantum mechanics suggests that an electron can only take specific energy states.
Furthermore, the probability of finding an electron in between these stationary states is zero. Therefore, the energy differences between the two stages are discrete values.
That means; an electron can absorb or emit energies corresponding to any difference between stationary states, but not in between. Excitation is the process of absorbing such a photon to go up to a higher energy level. The opposite process of excitation is emitting a photon to come down to a lower energy level. If the energy of the incident photon is sufficiently large enough, the electron will move to a very large energy state, thus removing itself from the atom. Absorption is a term we generally use to identify some quantity becoming a part of another quantity.
In chemistry, we mainly use the term absorption in the sense of electromagnetic waves.
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