Back-lit Gold Nanoparticles

[ATB510]

Hi all! Wanted to share this recent photo I took of some gold nanoparticles, and explain how it was done. First off, the photography:

Camera: D3100
Lens: 18-55 VR II
ISO: 100
Shutter speed: 1/125th @ f/9.0

All light was supplied by a SB-700 placed beneath the stage on which the vials are sitting, bounced off the white background (A4 sheets of paper). Strobe is @ 1/32 power, triggered by on-camera flash (-3 EV) bounced toward the ceiling so as to prevent reflections. I found it tricky to balance getting a perfectly white background, and not drowning out of the detail in the edge of the glass.

Secondly, the science:
These are nanoparticles of gold suspended in water, each vial contains a different size (red being the smallest, blue the biggest) ranging from 5nm to 25nm. They are really simple to make, in fact they were made by school kids spending the day in our lab, and as you can see they produce really neat colours. For the nerds out there, the colours are created as light interacts with surface electron resonance brought about by their small size.

What would I do differently?: I would add a glass pane underneath the vials to bring out the reflections, and add black card to the sides to bring out the edge detail.

Hope you like!

[asp7yxia]

I'd love to see the one with reflections off glass pane, that would be interesting.

While the photograph is amazing, I find the science behind it more fascinating