I had my own experience of Triboluminescence experience back in 2003 when I was defrosting a freezer with a hair dryer and blunt knife.   I must point out that the heat exchanger inside freezers are often made of aluminium and if you use a knife in the defrosting process, then you are quite likely to damage the freezer by puncturing the heat exchanger which basically means go out and buy another freezer. You have been warned and I know someone who this happened to!

Anyway, while I was defrosting, I thought I caught a glimpse of a little flash of pale green light in the freezer but managed to convince myself that it was just a reflection of the kitchen light on the silver case of the hairdryer. But then it happened again and I became convinced that light was being generated within the ice as I scrapped the knife over the ice and in particular, if I tried to lever the ice away from the roof of the freezer. I had only seen a few flashes by this time and thought I wouldn’t see any more, but just in case, I set up my camcorder which was an old VHS-C type on a tripod looking up at the area where the lights were occurring.

To my amazement, there were several more flashes during defrosting and I managed to capture them on the camcorder, so I frame captured one of the flashes and e-mailed it as a JPEG image to the MARA members then showed them the video at the next group meeting. A single frame from the video is shown below with the anomalous pale green light flash in the top left part of the freezer compartment.  To view the video of the flashes on MARA's Myspace site click here then click on view my videos, then click on Triboluminesence.  Click back on your browser twice to return here.

Ice flash (triboluminescence) shown as a pale green light in the upper left of the freezer compartment

I have since defrosted the freezer in the same way on two further occasions without any further ice flash, so I don't know what was different on the occasion that the ice flash occurred.  The web reference describing Triboluminescence is inadequate from a scientific point of view so I would like to hear from anyone else who has produced ice flash or any other form of triboluminescence, especially if they can do it repeatedly.  You can send your report to me billbimson1@yahoo.co.uk for it to be pasted on this page and you will receive full credit for it.

I don't know how Ice Flash works, but my hunch is that the crystal absorbs energy from the mechanical vibration of the bond breaking which raises an electron state in either the hydrogen or oxygen atoms (which make water molecules) and then re-emits the energy as light on return to equilibrium. I have no proof of this of course, it is just a shot in the dark. If the wavelength of the light emitted could be measured and found to be monochromatic, that would lend weight to my theory, because it would suggest a quantum change of fixed magnitude such as we have in different electron shells. If this were the case, we would be able to tell if the wavelength corresponded to a particular quantum change that was evident in either hydrogen or oxygen.

It is interesting to note that the Aurora Borealis or Northern Lights are produced when oxygen and nitrogen atoms are excited in the upper atmosphere and then return to equilibrium.  The colours produced are pink and green with the green being produced by the oxygen atoms and ice (water H₂O) of course does contain oxygen.  Have a look at the 2 pictures below of the Aurora Borealis and compare the green in them with the green in the freezer compartment.

Pictures of the Aurora Borealis taken from Shetland on the 20/11/2003.  The picture on the right is a whole sky image taken with a fish eye lens.  Both pictures are courtesy of Chris Brown.  Chris is a physiological measurement technician based in Shetland and writes a monthly astronomy article for the local newspaper.  For more spectacular pictures of the Aurora Borealis taken from Shetland by Chris Brown go to http://www.paddles.shetland.co.uk/Aurora%20images.htm