Mass-Spectrometry of Supersonic Cluster Jets of Methane and Argon-Methane Mixtures

Abstract

We describe a new experimental facility LEMPUS-2, which provides experimental research in supersonic flows of gases and gas mixtures in the oil-free vacuum. Model experiments in a flow of pure argon in order to verify and test the diagnostic equipment of set-up were performed. Experimental studies of the formation of cluster beams of methane and argon-methane mixtures have been performed to determine the optimal conditions for the formation of intense molecular beams of methane clusters. We obtain an intense molecular beam of methane clusters. It was found that in a supersonic jet of large size pure methane clusters are not diagnosed by the mass spectrum of oligomeric fragments, whereas in mixtures of argon with small admixtures of methane is recorded in the mass spectrum, apparently as oligomers of methane and mixed clusters of argon-methane . It was confirmed that the clustering of methane starts at lower pressures of inhibition than argon and lead to further delay of cluster formation in argon. It is shown that for high intensity methane clusters fluxes should be used specially selected gas mixtures