Alpha decay helium produced on Earth is the result of the alpha decay of underground deposits of minerals containing uranium or thorium. The helium is brought to the surface as a by-product of natural gas production. Alpha particles were first described in the investigations of radioactivity by Ernest Rutherford in 1899, and by 1907 they were identified as He ions. By 1928, George Gamow had solved the theory of alpha decay via tunneling. The alpha particle is trapped in a potential well by the nucleus. Classically, it is forbidden to escape, but according to the (then) newly discovered principles of quantum mechanics,
Nitrogen-15 nuclear magnetic resonance spectroscopy Nitrogen-15 nuclear magnetic resonance spectroscopy Nitrogen-15 nuclear magnetic resonance spectroscopy (nitrogen-15 NMR spectroscopy, or just simply N NMR) is a version of nuclear magnetic resonance spectroscopy that examines samples containing the N nucleus. N NMR differs in several ways from the more common C and H NMR. To lift the restraint of spin 1 found in N, N NMR is employed in samples for detection since it has a ground-state spin of ½. SinceN is 99.64% abundant, incorporation of N into samples often requires novel synthetic techniques. Two sources of nitrogen-15 are the positron emission of oxygen-15 and the beta