If both forms emit florescence, then one can apply a model of two-state excited-state reactions, see e.g.:

Article Analysis of two-state excited-state reactions. The fluoresce...

Therefore one may expect a bi-exponential fluorescence decay in the case of excited-state cis-trans (or vice versa) isomerisation..

Hi Koushik,

When ye have conformation change in a fluorophore, the excited sate conformation and inter system crossing is changing as well. Lifetime acts as finger print of those configurations. Any king of change in micro-environment inducing different lifetime. When you are modifying energy levels, you are manipulating lifetime that electron spending in excited sate.

Thank you so much Prof. Balter for the article.

Thank you Prof. Hamid for your valuable explanation.