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AFM/SPM training

Why you are here:


You are reading this web page because of your interest in AFM/SPM training in the Characterization Facility of the University of Minnesota. If you indeed seek to be trained, you need to email charfac@umn.edu and request placement on the training list (provided you have registered as a user of the charfac, via the same email address; thank you if you have completed these steps). You do not need to contact the staff member who will be training you in order to be placed on the training list; you must, however, immediately send an email to cfac-spm@umn.edu describing your research and the questions you wish to address with AFM. This will help to decide whether in fact you should be trained in AFM (i.e., note second bullet below), and on which instrument. (If pertinent, please provide a description of any previous experience you have with AFM, certainly the type/make of AFM and, importantly, the modes of operation you explored in your work including subtopics such as attractive versus repulsive regime in AC/dynamic/"tapping" mode, phase/friction/adhesion imaging, force curves/volume, etc. Most of our trainees opt for our full basic training sequence even if previously a user.) Finally, you need to state your scheduling constraints for the next two weeks. (Minor items on you calendar like "group meeting" or reschedulable appointments should be considered available time for training, per the recommendations of our advisory committees.)

Preliminary important points:

  • Please visit our General Policies web page, which is confirmed during user registration. All AFM trainees, by completing AFM training and proceeding to use the AFM labs, have thereby re-confirmed a full understanding of these policies. Any future staff time that is needed to reiterate/re-explain these policies or attend to violations of policy will be charged at our middle tier staff rate for both the time directly spent and for opportunity costs (minimum ½ hour).
  • Training (call this option 1) is suitable for those who will engage in a significant amount of usage, typically 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., you provide samples, we give you data). More substantial analytical jobs (in size 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).
  • Long-term usage data post-training has demonstrated that far too many people have sought training (at least HALF of those nominally trained in the past ~10 years). Wasted staff effort in training is no longer acceptable per the University's mantras on operational and scientific excellence. In particular, if you are from a research group with a track record of insisting on training then not following up with significant (or even any) usage, we will be skeptical of your claimed need for AFM training. Conversely if you are from a group that has generated "power users" in the past, we will hasten and cheer the process of training. In any case, please note that staff time spent training is always at the expense of months-overdue troubleshooting/repairs/improvement/development, funded research, service work, web development, marketing and more. As such, training that is not followed by substantial usage will be back-surcharged to cover the overhead of training (which is otherwise covered by subsequent user fees) as well as opportunity costs.
  • Beyond the initial training sessions, additional assisted session(s) are very often needed even for basic AFM methods (especially if your sample is difficult), and should be sought without hesitation. -- Our mission statement mandates that we train people to perform excellent analytical research (again, as part of the University's general mantra on 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 your research problem, usually within a scientific collaboration (option 3 above).
  • How much usage is "substantial"? Given that training (all of elements I-IV below) costs over $550, a subsequent total usage (again over months and years) that accrues to significantly 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!")
  • Get plenty of sleep and wear your thinking cap. If you think you are entitled to doze during training and yet be cleared to use $200,000 worth of sensitive equipment (and publish results in top journals), we reserve the right to cancel your training.

Training Description:

Training consists of four components:

    1. Self-study of principal conceptual elements of AFM (pdf and excel docs to be emailed to trainee; 0.5-1 day of effort):
      1. Read AFM Conceptual Guide (pdf of ppt in notes view);
      2. Run cartoon programs (download from SPM dropbox when prompted) to understand fundamental concepts;
      3. Submit completed prelim exam (excel file) to cfac-spm@umn.edu.
    2. Group demo session on spm1-2 OR spm3-4 (87 Shepherd OR 1-214 Nils Hasselmo), introduction to hardware/software (3 hours)
    3. Individual hands-on sessions with trainer (87 Shepherd OR 1-214 Nils Hasselmo) with trainee’s sample (3 hours)
    4. Mandatory prescheduled solo sessions 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:

    1. 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 (energy dissipation), 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.
    2. 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 analysis software routines.
    3. Hands-on using trainee's sample of greatest interest and relevance 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 (best seen twice, this time hands-on).
    4. 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 recommended 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 5-6 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 (i.e., rugged).
  • 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, particularly if using spm’s 3-4.
  • Difficult samples do not excuse a lack of subsequent usage following training. (Revisit the third Preliminary important point. There is no acceptable excuse for "punting".)

Document downloads:


Mandatory:
Brief SPM training overview  [  PDF 24kB]

Optional:
Full introduction to AFM (18pp)  [  PDF 1.3MB]
Clarification of "tapping" and non-contact  [  PDF 17kB]
Dissipation interpretation of phase  [  PDF 53kB]

Only for SPM1-2:
   SPM1-2 setup document  [  PDF 456kB]

Only for SPM3-4:
   SPM3-4 hardware  [  PDF 11MB]