Enthalpy of the N+ + H2 RIGHTWARDS ARROW NH+ + H Reaction-Experimental Study of the Reverse Process

Abstract

The formation of nitrogen hydrides in the interstellar medium is initiated by the nearly thermoneutral reaction of N+ + H-2 -> NH+ + H. Here, we experimentally determine the enthalpy of this reaction using the principle of detailed balance from a measurement of the rate coefficient of the reverse reaction NH+ + H -> N+ + H-2.

The measurements were carried out in a linear radiofrequency 22-pole trap combined with an effusive beam source of atomic hydrogen at temperatures between 10 and 100 K. The resulting ground-state energy difference (or reaction enthalpy at 0 K) of Delta E-0 = (18 +/- 4) meV confirms that there are no significant energy barriers on the reaction path.

Keywords

• Enthalpy
• Reverse Process
• NH+ + H -> N+ + H-2