Morpho Butterfly - Scanning Electron Microscope Images

[Ecki]

I managed to get hold of a Morpho sp. butterfly to "investigate" the scales. Morpho sp. butterflies produce the iridescent blue not through pigments but through nanostructures (structural color).


These are the two types of scales (called ground and top scales) that make the blue color. The difference between the ground and the top scales is the width between the ridges: large for the top and small for the ground scales. Nobody really knows why there are 2 different scale types that produce the same color.


Parallel ridge pattern of a ground scale


Ridge details of a top scale


Ridge details of a ground scale

The ridges are made of a layered shelf structure that is able to produce the blue color. The effect used is called Bragg reflection where light waves are reflected by a grid. The shelf structure resembles a grid. The light waves are reflected by different layers of the grid and the reflected light interferes thus giving us the beautiful iridescent blue color.

Best regards,
Ecki

[rjlittlefield]

Very very nice!

I am curious... In the first image the interior of the scales is dark, while around the edges there are areas that otherwise look similar but are much lighter. Do you know what causes the difference?

--Rik

[carlos.uruguay]

Wonderful photos and wonderful explanation!
Thank you for sharing these miracles of microscopic life

[pwnell]

Insane! Thanks for sharing. It is almost christmas.... I accept SEM donations

[Jacek]

revelation, love it

[Ecki]

Rick,

In the first image the interior of the scales is dark, while around the edges there are areas that otherwise look similar but are much lighter. Do you know what causes the difference?

This is a preparation artifact. I put some vacuum resilient resin on a stub and heated it to approx. 150°C. The resin melts and builds a sticky coating on the stub. Then I put the scales on the resin so when the resin gets cold and becomes solid, the scales are firmly attached to the stub and stabilized by the resin. Some of the resin penetrated the scales causing the lighter grey at the edges of the scale.

Without this "trick" the scales where so delicate that even at 0.5 kV acceleration voltage they startet to shake - causing "milky" images.

Best regards,
Ecki

[rjlittlefield]

Great -- thanks for the explanation!

Are these coated also?

--Rik

[Ecki]

Yes, they are. My earlier preparations were coated to granular but now with the help of a steal hose between the sputter coater and the vacuum pump, I reach 0.003 mbar so the platinum coating is very thin.

regards
Ecki

[piermicro]

very interesting indeed.

[Charles Krebs]

Stunning...!
Amazing to see this level of detail.

[discomorphella]

Really beautiful. What SEM conditions are you using (Vacc, deacceleration if any, beam current etc)? At some point I'll have some free time and I'd like to try putting a few scales into my SEM... Have you tried Ir instead of Pt or Pd for your conductive coating? I find it helps on really delicate samples that are likely to charge (and move...).
This is great.

David

[Ecki]

What SEM conditions are you using

These were made with 1 and 0.5 kV EHT, 3.5 mm working distance, 30 µm aperture in high vacuum at approximately 8 * 10^-6 mbar.

The beam of 1 kV is boosted to 9 kV in the column and slowed down to 1 kV in the final electrostatic lens (for details, google Zeiss Gemini column).

Best regards
Eckhard

[RogelioMoreno]

I always enjoy your SEM images.

Rogelio