Infrared absorption spectra of adsorbed dinitrogen on RuAl2O3K below 2000 cm−1

A new dinitrogen species is found by ir absorption at 1935 cm^?1 (Type B) when a dinitrogen species at 2020 cm^?1 (Type A) prepared from N₂ on RuAl₂O₃K is treated with H₂ above 170 °C or with NH₃ at 25 °C, or when H₂-treated catalyst is treated with N₂ at 250 °C. The Type B species is more reactive to H₂ or O₂ than the Type A species. Another ir band is found at around 1870 cm^?1 (Type C) when Type B species is evacuated at 200 °C. Both species, B and C, are likely located on the surface, while the Type A species is in an absorbed state. The Type C species is removed rapidly on introduction of H₂ or NH₃ at 25 °C, probably by displacement. The very low wavenumber, the high sensitivity to gases, and the high stability to evacuation disclose the unique character of the Type C species.