In my study, I developed two membrane materials: one without a ZnO coating and another with a ZnO coating. The diameter of the ZnO-NPs is approximately 30 nm. Using atomic force microscopy, I measured the average surface roughness (Ra) of both materials and found that the difference in Ra values between the coated and uncoated membranes is approximately 30 nm. This Ra difference closely matches the diameter of the ZnO-NPs.
Does this observation imply that the ZnO-NPs are arranged in a single layer on the membrane surface? If so, what additional characterization techniques would be most suitable to confirm this single-layer arrangement? Are there any potential exceptions or considerations. Thanks in advance
Indeed Ra does relate to the surface imperfection, since you immobilized ZnO-NP in/on a membrane matrix. However, it does not relate to single layer (directly). Let's say, assuming your particle are arranged on monolayer order, then you could do particle distribution analysis to the AFM images (use NanoScope Analysis software), and make several points of stacks from the histogram. If you have similar numbers (or almost similar numbers), then it means you have monolayer. Otherwise, if lower point gives you more numbers than the highest peak, indeed you have multilayer. Or you can compare with cross-section SEM.
Hope it works...
Dear Wisnu Sudjarwo
Thank you for the quick response! I will check the particle distribution histogram in Nanoscope and cross section SEM. It really helps
Dear Dr. Yumeng Guo
I agree with Dr. Wisnu Sudjarwo in that measuring the average surface roughness (Ra) for coated and uncoated membranes with no change in(Ra) value doesn't related the deposition of monolayer nanoparticles.
The lower the Ra value,the less variation between the peaks and troughs on a surface, making the surface smoother.
On the other hand ,The higher the Ra value, the higher variation between the peaks and troughs on a surface, making the surface rougher.
Now, when no change in(Ra) value, in this case , it should be no variation between the peaks and troughs on a surface,and also for many very different surfaces ,some uniform roughness, some with deep valleys or sharp peaks may all have the exact same Ra value. This is the background that has been drawn to many of the quality and warranty issues that we see as stemming from this shortcoming in micro scale Ra.
Best regards
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