He+ LEIS analysis combined with pulsed jet technique of ethanol sensing by a ZnO surface

Abstract Low-energy He+ ion scattering spectroscopy (He+ LEIS) was combined with the pulsed jet technique to analyze the outermost surface of a Zn-ZnO (0001) substrate that is sensing trace ethanol (EtOH, 50 ppmv) contained in the air. The gas sensing response to EtOH by ZnO under static atmospheric pressure was successfully simulated by the periodically pulsed gas jet irradiation onto the surface while keeping the background pressure low enough to operate He+ LEIS. It was found that the gas sensing response to EtOH is due to the surface compositional change analyzed by He+ LEIS. Thus, the gas sensing response to EtOH is caused by adsorption of EtOH-related molecules on the surface, which governs the oxygen ionosorption. It was demonstrated that the combination of He+ LEIS and the pulsed jet technique is a useful approach to analyze the outermost surface of a gas sensor in the realistic working condition.