If I understood correctly, you mean the mass transfer over surface due to diffusion. In this case the natural way to quantify mass transfer is to determine the diffusion coefficient. Can you please specify the question. I can also suggest reading of the following articles:

1) Theory of ripple topography induced by ion bombardment, J. Vac. Sci. Technol. A 6, 2390 (1988)

http://scitation.aip.org/content/avs/journal/jvsta/6/4/10.1116/1.575561

2) Ion‐beam‐induced topography and surface diffusion, J. Vac. Sci. Technol. 21, 790 (1982) 

http://scitation.aip.org/content/avs/journal/jvst/21/3/10.1116/1.571826?ver=pdfcov

I suggest you look at the attached paper, in particular Eqs. (7)-(14) and the related text. References [38-40] in that paper also have information on mass transfer.

Article Theory of nanoscale pattern formation produced by oblique-in...

Pearson Sir,

Can you suggest me some way to measure that mass transfer?

I have gone through these papers of Bradley Sir But the method given is not experimentally accessible?

The strength of the mass transfer effect is characterized by \mu_A and \mu_B in their theory. The Appendix in the following paper provides a detailed description of an experimental method to measure \mu_A and \mu_B. To the best of my knowledge, nobody has measured \mu_A and \mu_B for any binary material and ion species yet.

Article Theory of nanoscale pattern formation induced by normal-inci...

Sir ,

Actually the method given is tough to access. Plz suggest something easy.

I'm not aware of a simple method.  Perhaps you can come up with an easier one.

Note that there have been efforts to compute the mass redistribution coefficients from simulations --- see, for example, the work of H. Hofsass.

J.E. Greene (Ilinois) and L. Hultman (Linköping) have some nice papers too on these adatom mobilities.