How to turn chlorophyll red

What colour is chlorophyll? Obviously its green. After all chlorophyll is the pigment in leaves that absorbs the Sun's rays in the first step of photosynthesis. It reflects the green light which is why the leaves are that colour. But what colour is chlorophyll under UV light?

You'll need.

• Some green leaves, spinach works well.
• A pestle and mortar
• A clear spirit like gin or vodka (best to ask an adult before using this)
• An ultra violet torch 
• A glass 
• Some kitchen roll

What to do.

1. Put a few leaves in the mortar.
2. Pour in about 20ml of gin
   
   
   
3. Gently mash it all up with the pestle until the chlorophyll dissolves in the alcohol and the liquid goes green.
4. Filter the bits out of the chlorophyll extract by pouring it through some kitchen roll and into a glass.
   
   
   
5. Now shine the UV light through your green liquid. You'll notice that where the UV light passes through the chlorophyll extract a reddish light is emitted. 
   
   
   
   
   
   
   
   
   
   What's going on?
   Chlorophyll fluoresces, this means that it absorbs light of one colour and emits it as another. So in this case the UV light gets converted into red light by the chlorophyll. You wouldn't notice this effect in leaves because the chlorophyll is bound up with a huge amount of protein machinery that the plant needs for photosynthesis. These proteins take the energy emitted by the chlorophyll and pipe it into complex pathways that result in the plants using the suns energy to grow. But strip away the proteins, using some alcohol, and that energy gets emitted as red light instead.

Fancy some uranium?

Now, how about that uranium!

You can get hold of it really quite easily and better still it really does glow in the dark!

I'm actually talking about uranium oxide, not the metal itself. And you find it in some green glassware, were it gives a lovely minty colour. You might even have some at home without realising it.

Its easy to check if green glass contains uranium oxide because it fluoresces under UV light. Here's a bowl I bought for £5 under normal light and then under UV.

If you want to hunt some of this really cool (and slightly radioactive) glassware out then get yourself an ultra violet keyring torch and check out  green glass you come across in carboot sales, charity shops and antique markets.

Safety:
Fear not, uranium glass is safe. In fact when I ran a Geiger counter over this piece I couldn't measure anything above background radiation levels.

There may be a mild concern if you happen to have a large collection. But a small number of pieces is certainly nothing to worry about.

P.S. The ratio of uranium and oxygen in uranium oxides follows Fibonacci ratios i.e.  U₂O₅, U₃O₈, U₅O₁₃, U₈O₂₁, U₁₃O₃₄ ! Anyone care to explain why?