Because the nucleus of the most common isotope of carbon, carbon 12, has zero spin in total, the group used carbon 13 atoms, whose nuclei have the spin of their one extra neutron.

• 由于碳12（最常见的碳同位素）原子核的总自旋为零，所以这个小组使用碳13，其原子核自旋来自多出来的中子。