If you want to know the integrated emission at a certain excitation wavelength, just take the fluorescence emission using a fluorescence spectrophotometer, you will get emission intensity for different wavelengths. if you add those intensities between two selected points, you will get the integrated fluorescent intensity. Remember it will depend on many factors like

1) The range you are considering for addition

2) excitation and emission slit width

3) Concentration of the dye

Would something like this work?

http://www.sciencedirect.com/science/article/pii/S0022231305000402

If you specified your question, that would help greatly with answering it ;) What exactly are you dealing with, a single dot or an ensemble? Do you want to calculate or measure? What do you measure, how, and with what goal?

It would be difficult to give a correct answer with out knowing what you are specifically looking for. Probably you are looking for an integrating sphere to collect all the emission and calculate the quantum yield.

If you want to know the integrated emission at a certain excitation wavelength, just take the fluorescence emission using a fluorescence spectrophotometer, you will get emission intensity for different wavelengths. if you add those intensities between two selected points, you will get the integrated fluorescent intensity. Remember it will depend on many factors like

1) The range you are considering for addition

2) excitation and emission slit width

3) Concentration of the dye

Thanks Anil Chandra for your answer

Thanks for the paper Roman Kubrin

It really helped me a lot.