noun Date: 1939 an isotope of carbon of mass number 13 that constitutes about 1/70 of natural carbon and is used as a tracer especially in spectroscopy utilizing nuclear magnetic resonance
CARBON 13
Meaning of CARBON 13 in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012