O17

Oxygen-17 (O-17 or 17O) is a stable isotope of oxygen with mass number 17. Its nucleus contains eight protons and nine neutrons, and it has a nuclear spin of 5/2, which makes it observable by nuclear magnetic resonance (NMR) spectroscopy. Its natural abundance is about 0.037% of natural oxygen, far lower than the dominant O-16 isotope, which is about 99.758%.

O-17 is produced in stellar nucleosynthesis and occurs in trace amounts in the Earth's atmosphere and minerals. Because it is stable, it does not decay over time, but its low natural abundance means that experiments commonly use isotopically enriched materials or gases to achieve detectable signals.

Applications of O-17 include NMR studies of oxygen-containing compounds, where tagging molecules with 17O helps reveal bonding environments and exchange processes. It is also used in isotopic labeling for investigations of metabolic pathways and reaction mechanisms. In imaging research, 17O can be employed in magnetic resonance imaging (MRI) with hyperpolarized samples to visualize certain biological processes. In environmental and geochemical studies, 17O is used alongside other oxygen isotopes to investigate atmospheric chemistry, water cycle processes, and paleoclimate records, often via measurements of δ17O and related triple-isotope analyses.

Because of its low natural abundance, practical work with O-17 relies on enriched sources and sensitive detection techniques. Safety considerations are similar to those for non-radioactive, stable isotopes.