摘要：Adsorption and activation of dinitrogen(N_(2)) is an indispensable process in nitrogen *** nitride species continue to attract attention as a promsing catalyst for ammonia ***,the detailed mechanisms at a molecular level between reactive nitride species and N_(2) remain unclear at elevated temperature,which is important to understand the temperature effect and narrow the gap between the gas phase system and condensed phase ***,the ^(15)N/^(14)N isotopic exchange in the reaction between tantalum nitride cluster anions Ta_(3)^(14)N_(3)^(-) and ^(15)N_(2) leading to the regeneration of ^(14)N_(2)/^(14)N^(15)N was observed at elevated temperature(393-593 K)using mass *** the aid of theoretical calculations,the exchange mechanism and the effect of temperature to promote the dissociation of N_(2) on Ta_(3)N_(3)^(-) were elucidated.A comparison experiment for Ta_(3)^(14)N_(4)^(-)/^(15)N_(2) couple indicated that only desorption of ^(15)N_(2) from Ta_(3)^(14)N_(4)^(15)N_(2)^(-) took place at elevated *** different exchange behavior can be well understood by the fact that nitrogen vacancy is a requisite for the dinitrogen activation over metal nitride *** study may shed light on understanding the role of nitrogen vacancy in nitride species for ammonia synthesis and provide clues in designing effective catalysts for nitrogen fixation.