Recent results of the use of 15N as a stable isotope in reaearch work and technology

In the elucidation of processes in nature and technology involving nitrogen, the stable isotope 15N plays a significant role. From the variations in the isotopic composition of nitrogen in its natural occurrences, important conclusions can be drawn about the mechanisms active in the individual parts of the nitrogen cycle, provided that the isotopic effects of nitrogen are known. Since the radioactive isotopes of nitrogen are consistently very short-lived, only the stable isotope 13N is suitable for marking this element. After an introduction to the geochemistry and isotopic geochemistry of nitrogen, the prerequisites for an effective application of 15N are discussed: isotopic effects of nitrogen in isotopic exchange processes, liquid-vapor equilibria, photochemical reactions, and other processes form the basis for an effective separation of nitrogen isotopes. For the fully automated isotopic analysis of nitrogen, a device based on a spectroscopic isotopic effect has been developed by the Central Institute for Isotope and Radiation Research. The precision isotopic analysis of nitrogen, as required for the study of the isotopic geochemistry of this element, remains the domain of the mass spectrometer.