Polyaromatic hydrocarbons usually show emission spectra in UV range when excited with less then 300 nm range. But what if they show emission spectra in visible range after excitation with green pump? I am not sure why there is spectra in visible region at RT? I have not seen any literature except for two publications where they said resonance frequency is responsible for this transition in their setup and in another paper, they were using very high temperature which might shift the spectra towards red wavelength.
Check my paper in Anal.Bioanal.Chem. 2011 on PAHs.
Fluorescence is a specific property od each PAH - one excitation wavelenght and one for emission. That is all.
Regards
GB
resonance frequency of cause may be responsible for this transition
Article Sample preparation procedure for the determination of polycy...
It is the normal feature for PAHs that they absorb over a very wide wavelength range. Those are transitions to the 1st 2d and 3d excited electronic states
Emission is from the lowest excited state known as
Tee emissions wavelength depends on the number of conjugated benzene entities
You should study the absoprtion and emission spectra in basic handbooks of spectroscopy
What PAH do YOU have by the way
as a start here
via google "fluorescence spectra PAH" images
and here for free
https://books.google.nl/books?id=7eI3AVl4dDsC&pg=PA80&lpg=PA80&dq=spectra+PAH&source=bl&ots=0c_GJIyYc_&sig=ACfU3U1_r0_F54d9UaX60fpWMt8RsxQBew&hl=nl&sa=X&ved=2ahUKEwiChOmclr3nAhULaVAKHYHzDL0Q6AEwEHoECAgQAQ#v=onepage&q=spectra%20PAH&f=false
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