Oxygen-17 (17O) is a low-abundance, natural, stable isotope of oxygen (0.0373% in seawater; approximately twice as abundant as deuterium).
As the only stable isotope of oxygen possessing a nuclear spin (+5/2) and a favorable characteristic of field-independent relaxation in liquid water, 17O enables NMR studies of oxidative metabolic pathways through compounds containing 17O (i.e. metabolically produced H217O water by oxidative phosphorylation in mitochondria) at high magnetic fields.
Water used as nuclear reactor coolant is subjected to intense neutron flux. Natural water starts out with 373 ppm of 17O; heavy water starts out incidentally enriched to about 550 ppm of oxygen-17. The neutron flux slowly converts 16O in the cooling water to 17O by neutron capture, increasing its concentration. The neutron flux slowly converts 17O (with much greater cross section) in the cooling water to carbon-14, an undesirable product that can escape to the environment:
17O (n,α) → 14C
Some tritium removal facilities make a point of replacing the oxygen of the water with natural oxygen (mostly 16O) to give the added benefit of reducing 14C production.
The isotope was first hypothesized and subsequently imaged by Patrick Blackett in Rutherford's lab in 1925:
Of the nature of the integrated nucleus little can be said without further data. It must however have a mass 17, and provided no other nuclear electrons are gained or lost in the process, an atomic number 8. It ought therefore to be an isotope of oxygen. If it is stable it should exist on the earth.
It was a product out of the first man-made transmutation of 14N and 4He2+ conducted by Frederick Soddy and Ernest Rutherford in 1917–1919. Its natural abundance in Earth's atmosphere was later detected in 1929 by Giauque and Johnson in absorption spectra.
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Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a strong constant magnetic field are perturbed by a weak oscillating magnetic field (in the near field) and respond by producing an electromagnetic signal with a frequency characteristic of the magnetic field at the nucleus. This process occurs near resonance, when the oscillation frequency matches the intrinsic frequency of the nuclei, which depends on the strength of the static magnetic field, the chemical environment, and the magnetic properties of the isotope involved; in practical applications with static magnetic fields up to ca.
Oxygen-17 (17O) is a low-abundance, natural, stable isotope of oxygen (0.0373% in seawater; approximately twice as abundant as deuterium). As the only stable isotope of oxygen possessing a nuclear spin (+5/2) and a favorable characteristic of field-independent relaxation in liquid water, 17O enables NMR studies of oxidative metabolic pathways through compounds containing 17O (i.e. metabolically produced H217O water by oxidative phosphorylation in mitochondria) at high magnetic fields.
Heavy water (deuterium oxide, 2H2O, D2O) is a form of water whose hydrogen atoms are all deuterium (2H or D, also known as heavy hydrogen) rather than the common hydrogen-1 isotope (1H or H, also called protium) that makes up most of the hydrogen in normal water. The presence of the heavier hydrogen isotope gives the water different nuclear properties, and the increase in mass gives it slightly different physical and chemical properties when compared to normal water. Deuterium is a heavy hydrogen isotope.