Naked Science Forum
Non Life Sciences => Chemistry => Topic started by: matt katzenstein on 12/03/2011 01:30:04
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matt katzenstein asked the Naked Scientists:
Dear Chris,
A while ago I ordered some blue lasers online, I got them a few weeks later and was having a blast lasing things around the house to see if they do anything strange, like fluoresce or something, I happened to hit a bag of cashews with the laser and i noticed something very strange, the cashews actually showed some phosphorescence, they glowed a orangy green for about a second after I stopped shining the laser on them, they were actually showing weak BUT VISIBLE phosphorescent properties, I was very excited and started trying other organic things with the laser, I also found out that cashews, peanuts, and almonds all had the same effect to a limited degree, it turns out that peanuts has the longest and brightest glow of the different nuts I tested, also wasabi glows but very poorly. then i tested peanut butter and low and behold it glowed as well and better than all the others better than plain peanuts, (skippy brand) then I went on the internet and didn't find even a hint of a reason why this happens.
If you are stumped do i get a prize?
Cheers,
Matthew Katzenstein (Summit, NJ, USA)
What do you think?
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It's an oily, rather than specifically nutty, phenomenon ...
Fluorescence spectra measurement of olive oil and other vegetable oils.
Kyriakidis NB, Skarkalis P.
Agricultural University of Athens, Department of Food Science and Technology, Greece.
Abstract
Fluorescence spectra of some common vegetable oils, including olive oil, olive residue oil, refined olive oil, corn oil, soybean oil, sunflower oil, and cotton oil, were examined in their natural state, with a wavelength of 360 nm used as excitation radiation. All oils studied, except extra virgin olive oil, exhibited a strong fluorescence band at 430-450 nm. Extra virgin olive oil gave a different by interesting fluorescence spectrum, composed of 3 bands: one low intensity doublet at 440 and 455 nm, one strong at 525 nm, and one of medium intensity at 681 nm. The band at 681 nm was identified as the chlorophyll band. The band at 525 nm was at least partly derived from vitamin E. The low intensity doublet at 440 and 455 nm correlated with the absorption intensity at 232 and 270 nm of olive oil. The measurements of these fluorescence spectra were quick (about 5 min) and easy and could possibly be used for authentification of virgin olive oil.
http://www.ncbi.nlm.nih.gov/pubmed/11128149
BTW some of those laser pens available via the internet are dangerously powerful and could cause blindness.
http://www.thesun.co.uk/sol/homepage/news/2139862/Lunatic-tries-to-blind-pilot.html
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Ooohhhh... I'll have to try that! Peanut butter (yummy) and blue light...
I would re-iterate that you should be very careful with blue lasers. For the same laser power, the higher-energy photons can make them inherently more damaging, but for eyes the real danger is that the eye is relatively insensitive to blue so the blue laser appears far less "bright" than it really is (or than a green laser of the same power would look). This means that it won't generate the same degree of aversion (look-away / blink) response of other colours. Given my experience with high-power (1-3 watt) blue LEDs, I would guess that even if you only look at the laser spot as shone on a surface, you'll probably see temporary spots in your vision for a few 10's seconds. Take care.
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I must try that with the UV torches I use for leak detection. I have not tried food yet, but a lot of household stuff glows under UV light, the best being the laundry detergent.
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Yeah these were the cheapo blue lasers >2mW and i was trying to describe that they glowed after i removed the light source like glow in the dark paint and such, sadly we have no peanut oil in the house that I can try it on but I am going the store with my mom soon so I can try it there, don't worry I am being careful :)
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... sadly we have no peanut oil in the house that I can try it on
The fluorescence is not exclusive to nuts (http://www.thenakedscientists.com/forum/index.php?topic=37865.msg347245#msg347245).
NB:
The UK Health Protection Agency warns against the high-power (over 1 milliwatt) typically-green laser pointers available over the Internet, with laser beam powers up to a few hundred milliwatts, since they are "extremely dangerous and not suitable for sale to the public."
http://en.wikipedia.org/wiki/Laser_pointer#Hazards
The power and wavelengths output by "cheapo" lasers may be different from specified: the label may falsely say "<2mW" to get around legislation to prevent the sale of more powerful laser pointers to the public. I would be concerned your “cheapo” blue laser’s output may include invisible UV light (which it shouldn't) if it is capable of making things fluoresce. With invisible light which could damage your eyesight (UV or IR) the only way to be "careful" is to use filters which block it, e.g. in goggles.