In this article, I’m going to talk about what not to do in AFM. I’ll list 4 mistakes that are common in AFM use, which if you avoid, will certainly improve your results!
Using standard settings.This is possibly the worst mistake you can make. AFM imaging is a highly adaptable technique. It’s able to image very large samples of tens of microns with extremely rough topography, or make tiny images of extremely smooth samples with subnanometer features. There is no standard setting which will get good images of all samples. You need to be able to adapt the imaging settings based on the response from the instrument. Optimal AFM imaging is attained through an iterative process! If you don’t know how to optimise imaging of the AFM, I highly recommend revising chapter 4 of my book, “Atomic Force Microscopy”.
Interpreting image artifacts as image features. It’s important to know which features in your image come from your sample, and which are image artifacts. Learning this can save you some major embarrassment, and a lot of time!
|Example of image showing imaging artifacts. being able to spot and correct these artifacts is a crucial skill for an AFM operator.
- Trying to image dirty or contaminated samples. Sample preparation is the first, and most important part of an AFM experiment. If your sample has a layer of contaminant covering the the part you are interested in imaging, it will make your job almost impossible. Prepare your sample so that it only contains things you want to image.
- “Optimising” your imaging for a nice-looking amplitude (or deflection) image. I was amazed to find people do this. Amplitude and deflection images are made up of the error signal in AFM. The less contrast here is in the error signal, the more accurate your height image is. So, if you optimise imaging to produce a nice-looking high-contrast image in amplitude, you are decreasing the accuracy of your height image!
Avoid these pitfalls and your AFM work should be hassle-free! For help avoiding them I recommend reading my book, “Atomic Force Microscopy”, soon to be released in paperback!
All text and images copyright 2018 Peter Eaton, AFMHelp.com