To ensure that Ta 2NO + and Ta 2NOH 2 + are not somehow involved in the formation of Ta 2 15N +, quantum chemical calculations were carried out. However, on leaking 15N 2 into the ICR cell at a stationary pressure of 5.0 × 10 −8 mbar, a new signal D with Δ m = +1 relative to Ta 2N + is identified by exact mass measurements as Ta 2 15N +. When Ta 2N + is exposed to unlabeled N 2, no additional signal shows up. Ta 2N + apparently reacts with trace amounts of ubiquitous background gases, like oxygen or water, to form Ta 2NO + ( B) and Ta 2NOH 2 + ( C), with increases of Δ m = +16 and +18 relative to the precursor ion. 1 A was obtained when only argon was admitted to the ion cyclotron resonance (ICR) cell. Despite extensive experimental and theoretical studies ( 3, 5– 19) that have been carried out in the century following the invention of the H-B process, only little has changed in industrial nitrogen activation chemistry. For example, the Haber–Bosch (H-B) process operates at elevated temperature (300 ☌ to 500 ☌) and relatively high pressure (200 to 350 atm), and including the energy-intensive production of H 2 from CH 4, it has been estimated to consume 1 to 2% of the world’s annual fossil energy output and generates about 670 million metric tons of the greenhouse gas CO 2 ( 4). The biggest problem posed consists of breaking the extremely strong triple bond of N 2 (the bond dissociation energy amounts to 945 kJ mol −1) ( 2) this step corresponds to the rate-determining one in the large-scale ammonia synthesis and typically requires harsh conditions ( 3). Although dinitrogen is available in virtually unlimited quantities everywhere, its conversion into valuable feedstocks, such as ammonia, through sustainable processes still constitutes a major challenge. The element nitrogen is essential for life on Earth ( 1).

Ambient atomic orbitals