I found these particles in summer season and identified it such as organic particles called brochosomes, which are produced by leafhoppers if approx. 0,5 µm in diameter (see e.g. G.S. Casuccio et al. / Fuel Processing Technology 85 (2004) 763–779) or as Pollen if approx. 10 µm in diameter (see US EPA Guidelines for the Application of SEM/EDX Analytical Techniques to Particulate Matter Samples, 2002)

Pollen

Thanks for your answer, but pollen under 0.5 micrometer in diameter? Is that possible?

I am sorry, was not paying due attention to important "details"...

I hope EDS can help you. You have a lot non identified peaks on your spectrum, including the major one. You may want to try to acquire spectra from the single particle (it looks like the spectrum from your picture was acquired from some area, not from particle; too many peaks). Two spectra - even better. One at 15 kV (for heavier elements, but a lot of radiation will come from outside of your particle) and another at 5 kV (most of radiation will come from a particle).

Thanks! A friend is suggesting that these may be diatomaceous earth, de to the high amount of Si.

I found these particles in summer season and identified it such as organic particles called brochosomes, which are produced by leafhoppers if approx. 0,5 µm in diameter (see e.g. G.S. Casuccio et al. / Fuel Processing Technology 85 (2004) 763–779) or as Pollen if approx. 10 µm in diameter (see US EPA Guidelines for the Application of SEM/EDX Analytical Techniques to Particulate Matter Samples, 2002)

Thanks, Roman! Good idea. My only concierne is the largue amount of Si. What do you think about it?

It could come from the other particles you captured on the filter because of the interaction area of the electron beam and the sample. The other particles are sharped edged, containing Si, Al, Mg, Ca that indicates soil particles.

Great! Thanks for your help!!!

Dear Mr. Alfaro-Moreno

To identify crystal structure/phase structure of that material, X-ray diffraction analyze can be used, if it is available in your location.

P.S. If this material is polymer, your SEM equiptment's accelaration voltage (15 kV, writing under the picture as HV) is too high. It may be destroy also your sample's morphology.

Best Regards,

Fatih.

Thanks!

Roman Licbinsky - what an apt ID:

https://en.wikipedia.org/wiki/Brochosome

It had me stumped. I agee that the Si is probably coming from somewhee else.