Forums
Bruker Media
Community Media
Bruker AFM Probes
SPM Digest
Application Notes
NanoTheater
Website
中文
Brochures & Datasheets
Publications
Probes Catalog
Events
Manuals & Documentation
Presentations
Guide to AFM Modes
News
Journal Club
Webinars & Video
Nanovations
Other
for Peak Force QNM, and modulus meas, how do you reduce contribution from underlying substrate for soft and thin films, in other words what is the limit in sample thickness, does it depend on the hardness of the film?
With regular force volume, you were clearly dependent on the 200-300 nm below the probe (whatever the trigger treshold you selected). With HarmoniX, the influence of the underlying substrate was not so obvious (it was reduced to a few tens of nanometers). With peak Force QNM, it's in theory a couple of nanometers. The best test would be to image emulsions or Langmuir-Blodgett monolayers, and this is what I will try out in a few weeks... If you use ScanAsyst autocontrols, it should be fine. Now, if you turn them off and tap really hard, of course, you will have a strong influence of the sublayers.
Hi Sean,
Same rules will apply as with classical nano-indentation. If the penetration depth gets relatively larger, the more effect of the underlying substrate will be influencing the modulus measurement. For this reason you have to keep the penetration depth (deformation channel with the PFQNM mode) low. A good rule is to keep the deformation only a few percent of the entire sample thickness. In general it should not exceed 8 to 10% of the total thickness of the measured sample