I have nanorods grown by oblique angle deposition at 85 degree tilt angle, annealed in oxygen at 550°. The rods are approximately 50nm to 100nm wide by 400nm long, and primarily in the anatase phase, although I suspect a portion of them are amorphous. I would like to look at portions of the rods (inside compared to towards the edge) to see how annealing effects crystal growth. I need to transfer the rods to a TEM grid (which I have holey Carbon 400mesh) and get them to lay on their side. Has anyone done this or know of the best technique?
Dear
for single nano rod with altered structure,
Consider 1 micro gram sample with one litre insoluble so that they are disperded finely subject with high rpm or high say 1 lac.
Then take carbon or graphite rod dip it and remove so that very few will be settled on the carbon/graphite rod and subject to TEM to get desired
If single nano rod is not obtained repeat process with high amount of solute.
Hope it will serve the purpose
Post if any further queries exist
All the best
I would suggest to do a FIB preparation of your tubes. You could make a nice TEM cross-sectional preparation by FIB of your tubes and then also transfer this FIB lamella to a TEM grid in-situ using a nanomanipulator, which is typically available on any FIB system. Good luck! Best regards, Thomas
Out of curiosity, are these amorphous/crystalline nanorods photocatalytic? If they are, how do they rate against standard P25? thanks
These are anatase phase primarily, although we recently confirmed better performance with partially amorphous rods. The publication describing the activity compared to 25nm anatase particles is below, although we haven't compared directly with P25 mixed phase yet. We haven't yet optimized the rods, but have shown comparable results. One of the big reasons for imaging the rods (and gathering crystal info) is to answer the question you pose more deeply by understanding how the mixed phase results in better performance. I hope to correlate the crystalline structure to charge carrier lifetime and diffusion behavior. The publication below only covers high degree of conversion to anatase, so doesn't get into the mixed phase improvements. So, the short answer to your question is that it will be comparable once we get our results published. The benefit of this form is that as a thin film less about a micron thick, we can control the UV absorption, prevent light from escaping, and it is more mechanically stable than particles. There is a provisional patent.
Riley, M. J., Williams, B., Condon, G. Y., Borja, J., Lu, T.-M., Gill, W. N., & Plawsky, J. L. (2012). Photocatalytic Properties of Porous Titania Grown by Oblique Angle Deposition. Journal of Applied Physics, 111(7), 8.
Some questions for you (which will determine the answer to your question):
1) Do you have a FIB?
2) Are the nanorods somewhat attached to a substrate at deposition?
3) Your tubes measure 50nm wide x 100nm thick x 400nm long. Which cross-section(s) do you want to image?
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If no FIB, then go with Dr. Kumar's advice. Disperse the nanorods and you will get a random distribution of rods on your grid. The problem is that you will not have much choice as to what you can image. Most likely you will image the length of the rods with this method. Pros: quick, cheap. Cons: dirty, random.
If FIB, and substrate (I assume with that deposition method there will be a preferred orientation of growth for your nanorods), coat the finished nanorods with a low-Z material (a thick carbon coat will do). FIB any nanorod, any section you'd like. This is done all the time. Pros: Image what you like how you like it, high success rate on first try Cons. Expensive, time consuming.
If FIB and no substrate, you still want to embed the nanorods. You still have quite a lot of control with the FIB to find which tube to image and how to section it. However, it will take a little more time due to the lack of preferred growth direction.
I hope this helps.
Thank you for the response. I have no access to a FIB, and also don't think it provides any info on crystallinity or even bonding information (please correct me if I'm wrong), which is really what I'm after. It does provide concentration information for VERY low levels of material, but I'm afraid that info is less useful to me especially for the cost. I would like to get a cross section along the length of the rods. They are adhered strongly to the substrate
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