Dear Joko,

I suppose you are talking about ns or fs laser ablation.

The problem is quite complex and, as far as I know, there is no simple expression correlating the laser fluence to the ampunt of ablated materials.

By the way, some researcher have applied modeling techiques to extimate the ablated materials. I have attached a review reference as starting point.

Also these other references can be of help.

Pulsed-laser evaporation technique for deposition of thin films: Physics and theoretical model

RK Singh, J Narayan - Physical Review B, 1990 - APS

Pulsed laser vaporization and deposition

PR Willmott, JR Huber - Reviews of Modern Physics, 2000 - APS

R. Kelly, R.W. Dreyfus, Reconsidering the mechanisms of laser sputtering with Knudsen-layer formation taken into account, Nucl. Instrum. Methods Phys. Res. B 32 (1988) 341–348.

The evaporation model consists in considering the energy of the laser puls as an heat flux to the surface, than the Fourier equation is solved inside the solid, accounting also for the evaporation from the surface. The limit of this approach is that can consider only thermal evaporation while

there exist other mechanisms of matter emission from a laser hitted surface. The surface can melt, with the emission of droplets, esfoliation with the emission of solid particles to cite a few. In ns laser pulse, at sufficiently high pressure, there is the formation of a Knudsen layer that partially thermalize the emitted matter, loosing the memory of the emission mechanisms. These mechanisms can be put in evidence with a fs laser pulse and at very low pressure.

In my group we have followed a different approach, modeling the plasma expansion and changing the evaporation parameters to best fit experimental time of flights.

I hope it helps

Dear Gianpiero,

thanks for your answer and references, its very useful.

What is difficult for modelling is not so bad for experiments :) You can simply weigh a sample before and after irradiation. If the weight loss is too small to be precisely detected, you can do profilometry to calculate the volume and convert it to weight and then the number of atoms.