Dear Chandra,

penetration depth  is about 1 to 5 µm.

Please see page 2 of the paper at the attached 1st link,

page 7 of the 2nd link,

and page 19 to 24 of the 3rd link.

In the 4 th link you will find details on the Kanaya-Okayama Formula; see ref [2] therein.

Good luck

http://cfamm.ucr.edu/documents/sem-intro.pdf

http://academic.uprm.edu/pcaceres/Courses/CHAMINA/HO5.pdf

http://www.fhi-berlin.mpg.de/acnew/department/pages/teaching/pages/teaching__wintersemester__2013_2014/marc_willinger__scanning_methods_in_electron_microscopy__131122.pdf

http://www.globalsino.com/EM/page4795.html

• penetration depth  is about 1 to 7 µm

It will be totally depend on the applied electron beam energy.As the beam energy is increased, the electron beam can penetrate to greater depths.

It depends on electron beam energy and sample material. You may try simulating your experiment on CASINO software (it's free, if I'm not mistaken)

http://www.gel.usherbrooke.ca/casino/

It strongly depend on electrons energy

Yes. It strongly depend on electrons energy.

…

What ever the depth of penetration may be but the resulting EDS spectrum will only represent surface composition and for detailed and bulk specimen XRD or XRF should be used.

Dear Muhammad Kashif Samoon , everything you have said in your post is wrong.

Kindly explain it breifly so that wrong perceptions may be correctly solved and understood.

Which analysis gives bulk elemental composition from EDX, XRD or XRF and which one is reliable and widely used?

Dear Muhammad Kashif Samoon , you have written "What ever the depth of penetration may be but the resulting EDS spectrum will only represent surface composition". But actually EDS is not a surface technique. In many cases it's not a problem for EDS to determine a bulk composition.

Next you have written "for detailed and bulk specimen XRD or XRF should be used". But XRD in most cases is useless for composition. XRF for bulk analysis could be better than EDS, but it does not mean that EDS cannot be used. By the way there other means than XRF for bulk analysis.

And finally there was nothing about bulk analysis in the original question.

Thank you for elaborating. It will help alot many of us. Regards