Molecular beam mass spectrometry measurements of vibrationally excited N2 in the effluent of an atmospheric plasma jet: a comparison with a state-to-state kinetic model

Abstract

Abstract Vibrationally excited N2 molecules are suggested to be one of the possible key species responsible for the observed synergistic effects in plasma catalysis for NH3 synthesis. To assess the impact of vibrationally excited species in plasma-catalysis, quantitative measurements near interfaces are required, which remains challenging. In this letter, we report spatially resolved measurements of vibrationally excited N2 in the effluent of an atmospheric pressure plasma jet by molecular beam mass spectrometry (MBMS). The mass spectrometry signals as a function of electron energy of the ionizer were fitted with the effective electron-impact ionization cross section of N2(v) considering the vibrational distribution function as determined by a detailed vibrational level resolved plasma kinetic calculation. The reported method presented in this letter shows the capability of MBMS to measure vibrationally excited species of N2 near interfaces when the vibrational distribution function is known or assumed and shows excellent agreement with state-to-state kinetic models of N2(v).