Tuesday, May 27, 2008


Raman spectrometers tell scientists what almost any substance - solid, liquid or gas - is made of, eg. paint pigments on ancient temples on land but it also goes well under water.
The spectrometer works by focusing a laser on a target object. Most of the beam scatters off the object at the same wavelength as the laser. A small part of the beam (one in 100,000,000 photons) interacts with the chemical bonds of the molecules inside the target area and scatters at different wavelengths. Reading these wavelengths scientists can distinguish the composition of any samples collected.

Sheri White has helped develop the Deep-Ocean Laser Raman In-Situ Spectrometer (DORISS). This is a precision laboratory instrument in a pressure-proof container designed to work on the seafloor where many materials exist only in unusual conditions and can't be brought to the surface to study. She had already helped build and test ALISS (Ambient Light Imaging and Spectral System) to measure the light emanating from hydrothermal vents on the ocean floor. White was able to determine that the energy from this vent glow came from thermal radiation produced by extremely high-temperature (approx 350 degrees C) vent fluids.

A major problem with DORISS is the fact that spectrometers only see the precise point where their laser beam focuses, an area smaller than a pinhead and then it has to be held absolutely still for minutes at a time, something impossible to do from a ship at sea level to a ROV aat the end of a 4,000 metre tether on the ocean floor. White's answer was to build a 3-legged lab bench - Precision Underwater Positioner (PUP). This device complete with rigid legs, camera, light and crossing lasers helps to position the laser probe precisely and stably on the small targets in the deep ocean.

Chip Brier is a postdoctoral fellow who developed the Suspended Particulate Rosette (SuPR) to collect samples from the deep ocean vents. SuPR can collect 24 separate 100 litre samples where other samplers collect a single 2,000 litre one.

White and Brier are working to integrate a raman spectrometer into the SuPR for a trial run through a hydrothermal vent plume effectively analysing the chemical and trace elements as they emerge before combining and transforming as they interact with sea water. Then by taking a succession of samples they hope to record what happens as the chemicals and particles (eg. iron, manganese) interact with sea water elements (eg. vanadium, chromium) forming new minerals.


Brian Hughes said...

"Raman spectrometers tell scientists what almost any substance - solid, liquid or gas - is made of."

Ah...but could it work out the composition of Sedgwick's beard?

Anonymous said...

I like this post but I have found something that makes more money than I could do as a scientist with ideas that no one understood!!!!~ 600 an hour to dead shit rich men. Should have a house by next Xmas!

What makes the world go round I ask myself, with my profound scientific education? And new clients who hand over money like it's nothing.

The world is a strange place and most don't understand or value what means most in life.


JahTeh said...

I've been near Sedgwick's beard, it has a life of its own quite independant of the face it's grafted to. I wouldn't analyse it with less than 6 scientists and 4 lasers.

You have me worried anonymous, it sounds as though you've gone over to the dark side.

Lad Litter said...

Another great sci-porn post JahTeh! Let's hope it's used for niceness and goodness instead of meanness and rottenness.

JahTeh said...

Ladlitter, at the moment they can't make money out of it so we're safe. There was a scheme way back where they tried to scoop up the manganese nodules lying on the sea bed but I think the cost was too great.

Ann O'Dyne said...

That final photo is a lovely BLUE colour - sapphire blue ... haunting me.
while we are being scifientific can I recommend the blog onscreen-scientist.com
He is Bob Estes writing DNA software and a lovely man I found via normblog.
My new houseguest I found via normblog also: Thats So Pants ... from Hackney to Noosa via Mumbai and now in The Otways, god knows where she will end up next.

JahTeh said...

Annie, any man who loves a hamster that much deserves to be read. I hope Pants doesn't freeze to death, I've been awatching the night temperatures...icy.