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PeakForce QNM Probe Selection

It is important to choose a probe that can cause enough deformation of the sample and still retain high force sensitivity. Therefore cantilever stiffness should be selected based on the sample stiffness. Bruker's recommendations are shown in Table 1.

Sample Modulus (E)	Probe	Nominal Spring Constant (k)
1 MPa < E < 20 MPa	ScanAsyst-Air	0.5 N/m
5 MPa < E < 500 MPa	Tap150A, P/N MPP-12120-10	5 N/m
200 MPa < E < 2000 MPa	Tap300A (RTESPA), P/N MPP-11120-10	40 N/m
1 GPa < E < 20 GPa	Tap525A, P/N MPP-13120-10	200 N/m
10 GPa < E < 100 GPa	DNISP-HS	350 N/m

Table 1: Recommended Probes

NOTE: The recommended spring constants are general guidelines that reflect a compromise between image resolution and modulus accuracy. E.g. a stiff cantilever will improve modulus accuracy at the expense of damaging the sample.

To reduce optical interference, probes should be coated on their back side.

You may purchase these probes from Bruker AFM Probes at http://www.brukerafmprobes.com.

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