The interstellar synthesis of ammonia

The reaction H+3 + N → NH+2 +H has been measured in the laboratory at room temperature for the first time. It is sufficiently fast (k = 4.5 × 10−10 cm3 s−1) to provide a larger source of NH3 in dense interstellar clouds at 10 K than the more widely accepted source N+ + H2. At 50 K, both ion-molecule mechanisms (H+3 + N and N+ + H2) may provide roughly equivalent sources of NH3.