what do you mean by 'Mirror effect'

i know that MEF occurs when the distance between the metal particles and fluorophore

i never heard about this effect. what i know about MEF that for distances less than 5 nm the fluorescence is quenched event the field enhancement is big. what you can do is to perform FDTD simulation and calculate the field enhacement at 30nm for your the structures at the exciation wavelength. you will see if realy the amont of enhancement. FDTD simulation is a very powerful method. il will read the paper that you talk about and i will give you my opinion soon.

Thank Soroya,but unfortunately i am not a physicist,so i dont do simulations,but i would like to know more abt it.

unfortunately, my licence expired, otherwise I'll do it for you. sorry. for FDTD look at this website www.lumerical.com

Here, it is a historical article, Chance, Prock, Silbey, Please, use this link:

http://web.mit.edu/robertsilbey/research/papers/index.html

and read nr 34 and 35 (Lifetime of an Excited Molecule Near a Metal Mirror: Energy Transfer in the Eu3+/Silver System)

..there is a few another effect i.e. Rabbi oscilations, when you have resonator (two parallel mirrors)