Biodiesel fluorescence with medium powered green laser

[Tony]

Thought this might be of some interest - this is biodiesel with 70-100mW of 532nm green.  Attached are pictures of the beautiful orange/yellow fluorescence produced and a comparative photo of the beam brightness in free air (visible thanks to Rayleigh scattering). The fluorescence I did not expect and is surprisingly intense.

I've yet to try 405nm (the beam is a colour that can't be reproduced by a digital camera's colourspace, a mix of blue/violet) but it will be interesting to see if there is a similar effect.

[Tony]

A couple of other shots from tonight



What I found interesting about this is that there were flecks of green amongst the orange of the beam - this must be from impurities in the biodiesel.

And a night "breath shot" just for good measure

[julesandtash]

Somedbody has a new toy

Very interesting that the bio glows though - I would not have expected that

[Tony]

A new toy, ahem, scientific instrument for sure

Apparently both organic and mineral oils glow.  According to the wikipedia "Crude oil (petroleum) fluoresces in a range of colors, from dull-brown for heavy oils and tars through to bright-yellowish and bluish-white for very light oils and condensates. This phenomenon is used in oil exploration drilling to identify very small amounts of oil in drill cuttings and core samples."

It must be some property of hydrocarbon chains.

Apparently 405nm (blue/violet) causes peanut butter to glow for a short while after illumination.  Certainly for bio this wavelength is just absorbed with no obvious effect.

[Tony]

Some new photos:







Even 5mW 532nm produces this fluorescence.

Add a little Methanol and the whole mix turns green.

I'm a little disappointed that 405nm does very little (quickly absorbed producing a lilac colour).

[greasemonkey]

That is quite fascinating.
Is the laser some kind of pen, that you are shining into the bio, in the dark?

Is there some kind of horizontal layering in the last pic?
Wonder what that is, or is it just the way the container was dried, with a cloth?

I guess with enough experimentation, some useful data about the makeup of the bio must in there somewhere, for testing purposes, and that.

[Manfred]

I know Christmas has gone, but I need a new scientific instrument.
 Seriously though. How are you changing the wavelength and are these what you can shine through to check for soap dissipation.

[Tony]

If you want a green one, this is where I got the one above:

http://www.ecrater.co.uk/p/21614059/burning-laser-301-green-pointer-flashlight

It's quite the bargain.  The seller is chap in Greece called Chris who is happy to chat about them.  These are overspec so considerably over the 5mW limit - probably about the 70mW mark and easily capable of causing instantaneous permanent eye damage.  Because they use Nd:YVO4 to convert pumped 808nm to 532nm and are quite cheap, there is a good chance of infrared leakage too (no IR filter like expensive green lasers) which is also an invisible eye hazard.

You'll also need a Lithium Ion cell in 18650 form factor (mine are salvaged from laptop batteries) and a suitable charger.  It's best not to skimp on the charger as these cells are very picky about how they are charged (and like to explode if over-charged, or over-discharged).

I have a small collection of these lasers at different wavelengths and powers.

The last photo was a long exposure, moving the beam through the biodiesel.

There are little green flecks which show up in the otherwise yellow beam which I assume are dust or soap molecules.

[greasemonkey]

Ahh, I can understand the bit about moving the laser.
The rest, I tried running it through google translate, but it wouldn't convert it into HillBilly language.
I think I'll let you do the brains bit, and I'll just look at the nice pictures. 

[Julian]

Impressive stuff, but I'm working on a much easier way of going blind and it doesn't involve methanol.

[K.H]

Impressive stuff, but I'm working on a much easier way of going blind and it doesn't involve methanol.

Tosser!

BTW Tony didnt you have a play with a red pen laser, i remember seeing pics?

[Jamesrl]

Impressive stuff, but I'm working on a much easier way of going blind and it doesn't involve methanol.

Do you have to do that 'cause the tri nostriled one has banned you from the nether regions?

[Tony]

Impressive stuff, but I'm working on a much easier way of going blind and it doesn't involve methanol.

Tosser!

BTW Tony didnt you have a play with a red pen laser, i remember seeing pics?

Yes!  I still do for assessing soap in the water layer of a 50:50

Though now I've got a much more powerful red laser - not quite suited for the task

[Tony]

Diffraction grating arrived today