i have graphene mixed with ethanol and deposited onto metal substrate and subjected below AFM cantilever, but i'm getting unusually high noises in the image recorded, whereas when the same was tried with graphene mixed with polymer i was able to record some decent images.
Params in both cases
Setpoint: 20nN
Time:1.0s
Image size: 62.5um
Points/line:256
P-gain: 10000
I-gain:1000
D-gain:0
Could anyone find out my mistake and point it out, so that i may be able to correct it.
Dear.Lokesh Murali,
What kind of modes did you use? Tapping mode( non-contact) or contact? The tips are crucial to obtain a good quality of images.
Reduce the scan size, reduce the scan speed, and reduced the contact force. Adjust the P I D. Usually, one need to optimize those parameters. Use separate tip for polymer and graphene.
completely evaporate ethanol. reduce scan size and speed. also change the scan type. either tapping or non tapping. also calibrate the laser every-time before the beginning of test.
Xuhua Wang thank you for your reply, i'm using non-contact mode.
@Shashank i've tried all of those sir, but still i'm unable to get a good quality image.
@Fayzan the sample was heated to 70C before subjecting to AFM, i did reduce size and speed but could not get better results, as of now i'm currently using non-contact mode, i'm yet to try contact mode.
Thank you all for your replies. It means a lot. Excuse me for delayed response.
@Lokesh Murali,
You should use a new tip. From my experience, the tips are easily damaged.
The kind of horizontal striation that can be seen in the "graphene ethanol" image would suggest a poor or even repulsive tip-sample interaction. For instance, such condition can occur if the AFM tip surface shows hydrophobic behaviour while the sample surface is more on the hydrophilic side. Cantilever cleaning could help resolve the problem, eg by UV / ozone treatment to remove any non-polar residues sticking to the tip surface. Usually, UV / ozone exposure over 5 to 10 min does the job. Hope this helps. Best wishes, Martin
Dear Lokesh Murali ,
From your images it looks to me some low frequency noise is present, although it is difficult to say as the color bar scale is not visible in both images. It could be due to environemental noise or high adhesion between tip and surface. Environmental noise can be easily addressed with a freshly cleaved mica or HOPG sample. If you get a clear image with the same tip of atomic terraces, then you can discard it.
To check adhesion, best procedure is to make a Force vs distance curve in contact mode, with that you can check if there is a significant adhesion force difference that can explain your troubles. If that is so, then you would need to increase the setpoint force in the ethanol sample or change to a cantilever with higher spring constant.
Lokesh Murali I recommend you try to reduce the scan size, contact force, and scan speed, Adjust the P I D. Also, try changing the tip.
Dear Lokesh Murali
I second the suggestion from Nicolas F. Martinez
You may be getting disturbances from the substrate beneath. The substrates generally used to capture AFM for graphitic samples (like graphene, graphene oxide or reduced one) needs be absolutely clean with minimal surface roughness.
You will get a complete procedure to obtain apt surface for imaging graphitic samples in :Article Metal-Free, Graphene Oxide-Based Tunable Soliton and Plasmon...
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