Do you have the UV-vis spectra for both the cis and trans isomers?  If you do, I suggest that you photolyze the sample using a wavelength where one isomer has more absorbance than the other to observe if there are spectral changes on going from one isomer to the other.  Calibrate the number of photons from the light source using an actinometer, and repeat the experiment to determine the quantum yield for isomerization.  The actinometer should absorb in the same spectral region as your sample.  The procedure outlined here is experimentally straight forward and does not require a emission spectrometer or laser flash instrumentation. 

To obtain the lifetime and quantum yields for emission require different instrumentation, what instruments are available to you.  Let me know and I will elaborate on the lifetime and quantum yields for the fluorophore.

Hi Sumit.

I think the above mentioned answers are correct and will help you a lot. In addition, if you are asking for fluorescence properties in a photo-isomeric molecule, I suggest you to use a solvatochromic analysis in order to have more information about solvent polarity, polarizability, acidity and bacisity on the fluorescence caracteristics, in particular, the shape and energy of emission spectra. This kind of information is highly valuable in photo-isomeric fluorophore photophysics and more important, helps you to better understand the effect of the media and the nature of the isomerism in the excited state of the molecule.

Best wishes!

Thanks lot for  valuable suggestion. Really I am benefited fro these suggestion.

Presently I am facing the problem with highly photochromic material: 1) When I measure The UV-Vis spectra CIS isomer is convered to trans isomer during UV-Vis specral scan. Further there is significant change of fluorescence spectra with measurement with time (1 min interval). How do you measure the UV-Vis, Fluorescence and life time prperty of that molecules ????????????????????????????????