Use Acetone or IPA. I do not recommend the ultrasoud since it could break the nonorods. I think the best way is that using plasma ash or using O2- plasma.

Unless you use a clean-room, you always should have particles flying around, including much much human skin, yucky!. Then a good practice is to store immediately on individual containers. I like this one:

http://mtixtl.com/one55mmx55mm217x217gelstickycarrierbox-transparancecover-sp1-5510tbk-lh-p33.aspx

You may start ultra-sonicating your sample first in acetone or methanol, if you see that they will not damage or peel off your thin film. Then you can sonicate it in DI water and finally blown the sample with nitrogen or argon gas.

You can try this dust remover: http://www.photoniccleaning.com/

We use it to remove dust particles trapped in formed glass, and works very well. Of course I don't know how it would work with your nanorods, but it can be worth trying. Hope this helps. Regards,

In addition to Enrique's suggestion, It maybe related to the quality of the solution (viz. high molarity or the ratio of substances), the way to clean the substrate (use the soft surfactants), the drying/annealing conditions and so on. If you say more about the preparation details maybe more helps will be possible

Use Acetone or IPA. I do not recommend the ultrasoud since it could break the nonorods. I think the best way is that using plasma ash or using O2- plasma.

Exactly .. just immerse your film in acetone and IPA then wash it with DI water and dry it with Nitrogen or Just use the spinner and ofcourse all of that should be done in clean room.

if you will perform sonication make sure that your film "sample" is floating in the water bath to avoid the localized heat points in the base which will damage the nanorods. and make sure not to leave it over a min. as it is only for washing away the sticky particles and i'm not sure of the exact effect of long sonication time on ZnO nanorods.

There are several options. A simple sonication in IPA in clean room would help. If your thin-film coating is robust on substrate another option would be to use CO2 Snow-jet gun. I have used even IPA soaked cotton bud to rub physically the dust speck from thin-films and that also has worked. There are some soft lint-free wipes available for cleaning digital camera sensors, they also could be used after soaking in ethanol or methanol.

Thank you very much for the suggestions.

I ll try to sonicate in methanol and DI, for les than a minute, if it damages the nanorods then I ll try other method as you are all suggested. I ll let you know whichever method is working good.

sonication of nanorods films would not be great idea. it may be effective for a sample or two but cannot ensure nanorod adherence to the substrate. as i used to prepare nanorod solution in methanol using ultra sonication for TEM analysis.

There are several method to clean this dust. You mus wash samples with distilled water in sonication for one hour and then dry them in glow discharge box at 50 C for 3 hours.

Yes, most of the good tips are already offered and hopefully a combination of few would result in clean film. I just want to add one more tip that I found very useful in many such situations and that is to use ChloroBenzne [http://www.epa.gov/chemfact/chlor-sd.pdf]. It is now a days not easily found in labs due to its carcinogenic nature, but having said that, it is excellent cleaner for such situations. It may not work for your film as I never have experienced this problem so please try every thing else and if nothing work try this one too.

Good luck and let me know how you get on.

Thermophoresis force is widely applied in many aerosol related fields such as dust sampling or even collection of nano-particles.

I assume that the dust will deposit over your prepared nano-face by a thermophoresis force. Thermophoresis force means to create a temperature gradient between surface of your sample and the surrounding. If you can keep your sample at a lower temperature than the surrounding, it will prevent deposition of dust on your sample.

To prevent deposition of dust on the sample, the sample*s temperature should be higher than the surrounding temperature in order to creat thermophoresis force (temperature gradient)

Lightly pass air from air blow

Use ultrasuond with some mild etchant. Use can also use CO2 gun afterwards

Since all of the above did not work I suggest a dirty and easy way, if your film is strongly sticking to your substrate, is under a loop use a scotch tape on a q tip and press and remove the dust particles on your contaminated region of the sample. It is just a suggestion. Frankly there is no standard recipe for removing dust particles that is what clean rooms are for.

Also you can use paper for optics

Dear Millind

I did that too, but that doesnt help.

Dear Ahmed

I did try that, It looks clean (by eyes and optical microscope), however, when I checked the surface with SEM there are many sticky particles from the tape.

Dear Mehri

Actually I am thinking the same as you, that ll probably reduce the dust/precipitate and enhance the synthesis.

However, I ve never heard about the thermophoresis force theory before. This is interesting. It comes up with a new idea for me. Thanx.

Dear Enrique

Would you give me some information regarding the optics paper that you suggested pls?

The best method I can find so far is by sonicating it for 20 sec in IPA and then N2 gas gun afterwards (as Hojjat, Vibbu and other suggested).

The surface is clean, but I am not sure bout the internal structure (as far as I see from SEM image everything on the surface looks fine).

I am still looking forward to new comment or suggestion if any.

Thank you very much for all of your response.

I think the way of passing a slightly air is the best way, but if you think the films adhesion is very good you can use the washing by distled water

If they are carbon like dust you could think the possibility to heat it under vacuum in a O2 atmosphere. That works most of the time.

While thermophoresis and some other methods can work, I am afraid these dust-like particles might stick again when condition gets back to its stable state after the 'cleaning' process. I would suggest you carry out characterisation once again to determine exactly what these particles might be. This knowledge can help to come up with solutions to prevent this growth/sticking on production or cleaning method possible. That is my contribution.

Dust particles could be the impurities, please try to purify all chemicals before fabrication.

I will suggest you to share the SEM image first. So that one can have a look at it and tell whether its dust particles or growth contaminants like extra growth etc. (which are highly possible) Do share the image.

My group has been using FIrst Contact cleaning solution to clean contaminants from optics that cannot be removed with streaming nitrogen. After the solution is painted onto a surface, it dries into a thin plastic film. You then peel the film off with a slip of special paper. Our results for smooth glass surfaces have been excellent. The process has proven safe even for delicate (and expensive) coating. It might be worth trying for your system as well.

from my experience in ceramic membranes, I would suggest boiling DI water and washing thoroughly and consecutively in ethanol and acetone and store in a clean atmosphere. But I do not have experience in nanorods.

Alcohol can be used ... Or dm water ..but better to do all the experiments in clean room ...

@Mohammed AbdulWahhab Razooqi

Thank you for the suggestion. I did try that, however it doesnt solve the problem in our sample.

@Abner De Siervo

Thank you for the comment. We suppose they aren't carbon-like dust, besides we avoid too high heat treatment since we need to keep its defects concentration.