[Spm] Re: Spm Digest, Vol 43, Issue 7

[Ille Gebeshuber]

Betreff:
[Spm] Re: Spm Digest, Vol 43, Issue 4 drift in setpoint during friction 
measurement
Von:
Torbjorn Pettersson <torbjorn.pettersson at surfchem.kth.se>
Datum:
Mon, 11 Feb 2008 18:52:20 +0100
An:
spm at spmlist.di.com
An:
spm at spmlist.di.com

Dear Muriel Beauvais,
The source of the drift can origin in thermal drift. But it is hard to 
tell without more precise details.
For how long time have the instrument been switched on?
What is the temperature on the solution when injecting in the liquid cell?
How long time do you wait after the injection until measurement?
How stable is the temperature in the room where the AFM is located?
Are you using old or new type of the o-rings?

How large is the drift? (approximately X mV / 10 minutes)

I will also highlight the fact that the friction deflection sensitivity 
is varying when using liquid compared to air. See for example /Review of 
Scientific Instruments/ *78*(2007), 093702. /

/Best regards,
Torbjörn
 > Message: 2
 > Date: Tue, 5 Feb 2008 15:28:06 +0100
 > From: "Beauvais, Muriel" <Muriel.Beauvais at saint-gobain.com>
 > Subject: [Spm] setpoint drift
 >
 > Dear Colleagues
 >
 > When doing friction experiments in water with a Nanoscope 3a (Digital 
Instrument), I adjust the setpoint with the force calibration command 
before increasing the contact force of the tip (silica sphere of 5µm in 
diameter) on the sample (hard oxide). A continual drift in the setpoint 
value appears during the measurement. How could you explain this drift?  
How can I be sure that for each experiment, same loads are applied to 
the surface?
 >
 > Thank you very much
 >  
 > Muriel Beauvais