Carbon material doped with hetro atoms; when excited at 546 nm light (green)- they emit pink color? but when Emission spectrum was measured it show three peaks in red, blue and green region?
I want to know that how light (546 nm) of lower energy give higher energy emission?
can you please provide some more information like the emission spectra and the scan range etc.
You shouldn't and can't record spectra above excitation energy. Secondly there is no wavelength for pink color in electromagnetic spectrum, it's a mixture of two colors.
Is it laser excitation? If not, and if it is monochromator based without long-pass filters, the excitation light will also have the 2nd order diffraction at 273 nm (half 546 nm).
If it is laser excitation, then I would suggest that you measure the lifetimes for the different emission peaks. I would also suggest that you look at the wavelengths to see if it could be sum-frequency generation, and consider other nonlinear optical phenomena. Assuming of course that you are not using other sources of energy to pump the carbon material at higher energy state.
As in the case of Raman spectroscopy, where the observed spectra contain Stokes and anti-Stokes components, in fluorescence spectroscopy one similarly observes components shifted in energy: red-shifted (Stokes - recall the Jablonski diagram) and blue shifted. Consult [1], which is the standard text on fluorescence spectroscopy. In the case of the Raman spectra, the Stokes component corresponds to emission of phonons and the anti-Stokes component to absorption of phonons. Mathematically, and also physically, to appreciate the appearance of side-bands in spectroscopic spectra, I recommend you to consider the Rabi problem in quantum optics, where the main peak and the side-bands directly follow from the solution of the Bloch equations [2] (Sec. 15.6 of this reference is devoted to the problem of resonance fluorescence).
[1] JR Lakowicz, Principles of Fluorescence Spectroscopy, 3rd edition (Springer, New York, 2006).
[2] L Mandel, and E Wolf, Optical Coherence and Quantum Optics (Cambridge University Press, 1995).
First thing I used fluorescence microscope- it has four tunable wavelength: light source was (Hg 100W) 280, 365, 420, 546 nm.
Emission spectrum recorded from 200-1000 nm
280 ex. emission color blue
365 ex emission color aqua (same seen under UV 365)
420 (blue)(ex) emission color green
546 (green) emission color pink
At first three wavelength emission spectrum was following the typical higher wavelength emissions. But at 546 nm the emission color was appeared as Pink (Blue+Red mixing@) and emission peak recorded in whole visible spectrum?
I want to get insights why this happened only at 546 nm and how lower wavelength emission originated from higher excitation.
Majid Basharat : For insight, consult the book by Lakowicz to which I referred earlier. It is a very readable book in almost 1000 pages, replete with many theoretical and real experimental examples.
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