Dear all,

I would like to use a thickness monitor (TM) to estimate the mass of unkown
 material's we evaporated.
(As you may know well, the density and Z ratio should be known to measure
 the thickness.)
The TM can detect the change of resonance frequency with a relationship
 between the mass and the stiffness.
Therefore, I think the mass change could be taken simply without measuring
 resonator's initial mass.
Could you please advice me about this work?
Thank you in advance.

Lee