What do you mean by raw data? The individual photons hitting the detector?

yes. I have saved the data in excel. But can't create the plot.

What are you wanting to plot?

I like to plot the intensity vs diameter.

I usually like to use igor program for my analyses.

When I try igor, it is not giving me the plot I want.

Madam the raw data in origin, intensity (y-axis) and diameter (x-axis), then plot it, you will get a peak or peaks may be different places from there most probable particle size ....calculate it

Thanks. I tried with origin too. It does not do it.

That's why I am curious to know.