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Hi, All,
I calculated deflection sensitivity using two force curves from the same probe under the same conditions except for the trigger threshold. One force curve was obtained with a trigger threshold of 0.1 v, the other was obtained at 1 v. The deflection sensitivity data were different. The latter one should be more accurate. However, when I actually measure forces using the probe, I intended to set at a low trigger force, and the forces to be measured are also going to be low (20 - 150 pN). Shall I still use the deflection sensitivity obtained from the 1 v force curve?
If I should use the 1 v force curve. I am going to face a problem. The tip is functionalized with molecules. If I use a strong force to obtain the deflection sensitivity, the molecules might be damaged. Is there any solution?
Thanks a lot,
Shiyue
Dear Shiyue,
This is a very simiar problem to http://nanoscaleworld.bruker-axs.com/nanoscaleworld/forums/p/1411/3942.aspx#3942. It would be interesting to know by how much the two deflection sensitivities differ from each other, which one of the two is higher and especially how high they are.
What you need is a fairly linear curve; as long as you can obtain such a curve, you might be better off using the same magnitude of forces as in your measurements. One reason why your measured deflection sensitivities differ might be that you actually do damage your molecules already, leading to some additional deformation.
Best regards, Dietmar Haba
Dear Dietmar,
Thanks a lot. Your information including those in the link is very helpful. Later, when I paid more attention on getting a linear force curve, the values actually did not vary too much. They were within 5% variation. So, I will use the value obtained under similar conditions used for actual force measurements.
Thanks again,