RELAX is an instrument used to measure xenon isotope ratios. Contrary to popular believe, this does not mean we sit around the lab with our feet up all day!
RELAX stands for Refrigerator Enhanced Laser Analyser for Xenon. It is a unique instrument originally designed in the 1980’s, which is continually being improved. It is the world’s most sensitive instrument for measuring xenon isotope ratios. RELAX can detects just a couple of thousand atoms of xenon, a tiny amount when compared to approximately 1,000,000,000,000,000,000 atoms of sodium and chlorine in a single grain of salt.
2 important features contribute to the high sensitivity of RELAX:
- Xenon ions are made by a process know as resonance ionisation. This is a selective ionisation process which uses a laser tuned to a very specific wavelength so that only xenon atoms will be efficiently ionised. This allows for the detection of very small quantities of xenon in the presence of much larger quantities of other species.
- There is a cold spot in the spectrometer, held at -193 oC (80 K). Xenon in
the mass spectrometer condenses on the cold spot before
being released by a pulse from a heating laser. This has the effect of concentrating the xenon, and the ionization laser is then fired through the resulting plume.
RELAX is a time of flight mass spectrometer – the isotopes are separated out according to mass because the lighter isotopes travel faster and reach the deterctors before the heavier isotopes.
- Identification of the most ancient water, which formed within 2 millions years of the formation of the Solar System, trapped in tiny bubbles inside salt crystals in the Zag meteorite.
- Demonstrating that the oldest samples of the Earth’s crust incorporated 244Pu as they formed 4.3 billion years ago.
- The first xenon isotopic analysis of material from NASA’s Genesis solar wind sample return mission.
- Analysis of samples returned to Earth by NASA’s Stardust mission.