Heterogeneous reactions between ions NH$_3$$^{+}$ and NH$^{+}$ and hydrocarbons adsorbed on a tungsten surface. Formation of HCN$^{+}$ in NH$^{+}$-surface hydrocarbons collisions

TL;DR

This study investigates ion-surface reactions involving NH3+ and NH+ ions with hydrocarbons on tungsten, revealing formation of various ions and identifying conditions for HCN+ production, relevant for understanding surface chemistry at different temperatures.

Contribution

It provides new insights into the reaction pathways and energy thresholds for ion-induced surface reactions involving ammonia ions and hydrocarbons on tungsten.

Findings

Formation of NH4+ and related ions at low energies.

Detection of HCN+ formation with NH+ ions and a threshold around 40 eV.

Reaction activation energy estimated between 2.4 and 3.2 eV.

Abstract

Interaction of NH$_3$$^{+}$ (ND$_3$$^{+}$) and NH$^{+}$ with a hydrocarbon-covered tungsten surface kept at room temperature and heated to 150{\deg}C and 300{\deg}C showed a series of reactions between the projectile ion and hydrocarbons adsorbed on the tungsten surface. Collisions with NH3+ and particularly with ND3+ showed formation of NH$_4$$^{+}$, HCNH$^{+}$, and CH$_2$NH$_2$$^{+}$ and ND$_3$H+, HCND$^{+}$, and CH$_2$ND$_2$$^{+}$, respectively, with NH$_4$$^{+}$ (ND$_3$H$^{+}$) strongly prevailing at low incident energies of the projectile ion. No formation of HCN$^{+}$ (DCN$^{+}$) could be positively identified. In reactions with NH$^{+}$ formation of HCN$^{+}$ was clearly observed; the dependence of the HCN$^{+}$ normalized ion yield on incident energy seems to indicate a threshold at about 40 eV which may be due to an activation energy or an endothermicity of the surface reaction of about 2.4-3.2 eV.