Dear Timofey,

Can you please specify the brand and model of your QCM System, and which kind of crystal are you using?

Please check the 1st paragraph of Experimental Section of this paper: https://www.researchgate.net/publication/278673930_Study_of_in_situ_adsorption_kinetics_of_polyelectrolytes_and_liposomes_using_quartz_crystal_microbalance_Influence_of_experimental_layout

Sometimes the type of crystal cut and electrodes may have influence in the operation in certain conditions/materials!

Best regards,

Luis

Article Study of in situ adsorption kinetics of polyelectrolytes and...

Hi,

first and foremost is, of course, to check the settings. Are the density and the tooling factor correct? You may also use one trick: decrease the density 10 times, so you'll gain some more sensitivity (this would make your reading less accurate of course). Are you sure that your Sn atomic beam hits the QCM? Is the shutter open, if you have it? You may want to try to cover the quartz crystal with W again, in order to increase the sticking coefficient of the surface. Upon deposition of tungsten you would also double-check that you QCM is working correctly.

Personally I have somewhat contradictory experience with films thickness estimation from QCM reading... for monolayer and sub-monolayer coverages it was simply disastrous, but for fairly thick layers e.g. 150-200 ML of iron, the results were pretty accurate.

Hope that helps

Best

Nikolay

Hello,

Luis, thank you for the useful information. The crystal is AT-cut with resonant frequency of 60MHz. Currently the frequency is at ~59.8MHz and crystal life used is only 2%. The monitoring system is Prevac TM13 which has 0.1Hz resolution. The QCM is water cooled with the water in the lines at ~20C.

Nikolay, thank you for the useful suggestions. I will try to cover the crystal with W again.

Best Regards,

Timofey

Please, tell about the results: would it help covering the crystal with some active metal?

Hello,

It did not help to cover the crystal with W but it did verify that the QCM works for W since I reproduced previous readings. When I tried Sn deposition again (also reducing the density 10 times), there was no reading for thickness and the frequency remained constant. I am suspecting that either there is an alignment issue or that the radiative heating from the Sn beam results in a crystal frequency increase which cancels out the frequency decrease due to deposition. I will try to find the proper evaporation parameters without the QCM by depositing onto my substrate and checking the results in STM.

Timofey