Hi Debabrata

I'm not sure how you do it in Origin 8, but I can guide you to another (free) software which does it for you:

http://www.fluortools.com/software/anifit

Best,

Søren

Hi Soren its quite easy by using origin take the raw data than apply r(t) equation with known g factor and we will get the anisotropy and fit it.

Soren,

May I suggest using tail matching, rather than messing around with the g factor. As long as the rotational correlation time is shorter than the fluorescence decay time, than you will not have the nontrivial hassles associated with determining g factors.

The basic idea is that at long times, t, after excitation the curves I(t)-parallel and I(t)-perpendicular will become identical. Using this information you can scale the two curves, and then determine r(t).

Reference (text): "Time Correlated Single Photon Counting" by Desmond O'Connor & David Philips

Best

John

Please answer some of my questions regarding the data fitting of anisotropy decays..

1) How do we choose the value of g factor while giving it manually not automatically?

2) can rotation time of the molecule be larger than its fluorescence lifetime?? I think rotations should be complete before the molecule comes down to the ground state??

3) is there any significance of the value of initial residual anisotropy for the lifetime values??

Thanks Dr. Peter Kapusta for your answer