AFM/SPM Training

Thank you for your interest in AFM/SPM training in the Characterization Facility of the University of Minnesota!

If you wish to initiate training at this time, please email charfac@umn.edu and request placement on the training list (assuming you are a registered user of the charfac, via the same email address). You do not need to contact the staff member who will be training you in order to be placed on the training list. It is essential, however, to answer the ensuing questions from charfac@umn.edu in sufficient detail; you may alternatively email cfac-spm@umn.edu with replies to the following:

  1. Describe your research questions (to address the appropriateness of AFM).
  2. Describe any previous experience you have with AFM, including the vendor/model and the modes of operation you explored in your work (including more detailed subtopics such as attractive versus repulsive regime in AC/dynamic/"tapping" mode, phase/friction/adhesion imaging, force curves/volume, etc.).

Preliminary important points:

  • Please visit our General Policies web page, which is confirmed during user registration. Proceeding with AFM training and usage implies a full understanding of these policies. Staff effort attendant to violations of policy will be charged at the top tier staff rate (minimum ½ hour, >$50).
  • Training (call this option 1) is appropriate for those who will engage in a significant amount of usage, meaning months or years of frequent use. Short-term analysis of a small number of samples should be performed by the CharFac staff as an analytical service (option 2) if simple in method and information (i.e., user provides a few samples, we provide data). More substantial analytical jobs (in size or difficulty and/or because of advanced measurement methodology and/or advanced data analysis) should be performed by the CharFac staff in collaboration (option 3, in which case co-authorship is implied per scientific norms and journal guidelines).
  • Two decades of usage data demonstrates that many who have sought training have not followed up with significant usage. This is a waste of University and publicly-funded resources (at the expense of other work not getting done). As such, training not followed by significant usage will be back-surcharged to cover the overhead of training (which is otherwise covered by ensuing user fees) as well as opportunity costs for the staff.
  • Beyond the initial training sessions, additional assisted session(s) are very often needed even for basic AFM methods (especially if your sample is difficult), or even basic image processing, and should be sought without hesitation. -- Our mission statement mandates that we train people to perform excellent analytical research (as part of the University's general theme of excellence).
  • Beyond basic training there is much more one can, and usually should, learn to do with AFM (i.e., more advanced, and more correct, measurement methodology and/or data analysis) and thus we encourage further training. Experts can advise on and help you develop higher methods in the context of a research problem, usually within a scientific collaboration (option 3 above).
  • How much usage is "significant"? Given that basic training (meaning all of components I-IV below) costs over $700, a subsequent total usage (over months and years) that accrues to far less than this amount does not make sense. This would be equivalent to say <20 hours on the instrument. (And any avid AFM user would say, "well, DUH!")
  • Please arrive well-rested and ready to wear your thinking cap for 3-4 hours. You will be learning a lot of details, anchored by a wealth of materials and measurement science.

Training Description:

Training consists of four components. NOTE: Trainee must be able to allocate ample time for all of the below - accommodating staff calendars -- otherwise training should be postponed. It is unacceptable to cram in training just to "get it done". (This will result in the need for retraining with further delay and charges on top of wasted early efforts.

I. Self-study of principal conceptual elements of AFM (pdf and excel docs to be emailed to trainee; 0.5-1 day of effort):

a. Read AFM Conceptual Guide (pdf of ppt in notes view);

b. Run cartoon programs (download from SPM dropbox where prompted in the Conceptual Guide... this is not optional!) to understand fundamental concepts;

c. Submit completed prelim exam (excel file) to cfac-spm@umn.edu.

II. Group demo session on spm1-2 AND spm3-4 (87 Shepherd and 1-214 Nils Hasselmo), introduction to the hardware/software (2 sessions of 2 hours each) of basic modes, plus brief description of certain advanced methods.

III. Individual hands-on sessions with trainer (87 Shepherd OR 1-214 Nils Hasselmo) with trainee’s sample of greatest research pertinence (3 hours)

IV. Mandatory solo sessions (time charged whether or not used) with optional assistance (87 Shepherd OR 1-214 Nils Hasselmo; 10 hours in no more than three weeks but beginning within a day or two of part III.) Reporting results.

In detail:

I. Principles of the technique in AFM Conceptual Guide: tip/cantilever, force measurement, Z dependence of forces, XY scanning, topographic imaging under feedback, three fundamental surface tracking modes (contact, force-curve mapping, AC/"tapping"), compositional imaging and measurements via friction force, adhesion, stiffness/compliance and phase, attractive/repulsive regimes and dynamic bistability in AC/"tapping" mode. Quantitative issues in resolution, height measurement, roughness, grain size, and the representation/analysis of data.

II. Setup of sample/cantilever/laser/photodiode/video/software, approach to tip-sample engagement (optical and thermal artifacts), force curve acquisition, set point adjustment and tip state diagnostics, image acquisition details in multiple modes, zooming/translation (piezocreep artifacts), core software procedures for post processing (issues of raw versus modified data, nonlinearity, masking), image rendering, quantitative software analysis routines.

III. Hands-on using trainee's sample of greatest pertinence to the research project, usually concentrating on one tracking mode following the performance assessment of 2-3 modes, in turn a function of the nature of the trainee's sample and research questions. Repeat of introduction to software in acquisition and post processing (this time hands-on).

IV. Minimal time on instrument to (i) master hardware and software and (ii) connect these hands-on aspects to the information in the AFM Conceptual Guide. Mandatory check of data quality (submit at least one raw and processed image file by end of 3-week period, justify mode selection), as insisted by faculty advisory group.

Your sample: (i.e., Session III and beyond)

  • Firstly, note that "material" is not the same as "sample" in the context of microscopy. In AFM, by "sample" we mean something in a form that is ready to be engaged and imaged by an AFM tip. In particular, if your material is in a vial, it is most likely not yet an AFM sample!
  • If a solution or suspension, your material will need to be dried; or, conversely, imaged while immersed in the AFM liquid cell (after you have undergone more advanced training), but necessarily adsorbed to a substrate.
  • If a powder, then you need to come up with a scheme to make a sample appropriate to AFM. Our standard scanners have a Z range of 5-8 microns, limiting the ruggedness of the surface you are able to track and image (e.g., after compressing a powder into a tablet, or sprinkling powder grains onto a substrate, or dissolving/suspending powder in liquid and casting at low concentration on a very flat substrate and drying). The more rugged is your final surface, the more difficult to characterize the small (perhaps nanoscale) structures of interest to you. If you can visually see features on your surface (i.e., within light microscopy resolution), the surface is quite likely a mountain range on the AFM scale.
  • The visual positioning of the cantilever and laser via a video microscope will be aided by a reflective sample and hindered by a non-reflective sample. That is, the less mirror-like your sample is in appearance, the more difficult will be this visualization, and more so if using spm's 3-4. (White samples such as pharma tablets or compressed powders may be difficult in this regard.)
  • Difficult samples do not excuse a lack of usage following training. (i.e, a waste of trainer's effort). If concerned about this issue, allow the staff do initial work to determine feasibility.

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