The coupling of a reflectron time-of-flight mass spectrometer with a cosmic simulation chamber: A powerful new tool for laboratory astrophysics

摘要

The addition of an orthogonal reflectron time-of-flight mass spectrometer (ReTOF-MS) to the NASA Ames cosmic simulation chamber (CSC) experiment is described. The simulation chamber contains the elements that produce the molecular species under astrophysically relevant conditions. A pulsed discharge nozzle (PDN) produces ions, neutrals and radicals in a plasma discharge, which are then expanded and supersonically cooled into the chamber. The coupling of the ReTOF-MS to the CSC provides real-time identification of the species, including cations and neutrals, formed in the plasma, an insight into the chemical pathways of the species reacting in the plasma, and an efficient method for the quick determination of the species present in the plasma, which can then be probed spectroscopically with the cavity ring-down spectrometer (CRDS). The combination of the ReTOF-MS, CRDS and PDN components into a single instrument offers a powerful tool, which can be used to probe a variety of different astrophysical environments such as interstellar clouds and planetary atmospheres. The experimental details and representative mass spectra are presented for plasmas generated in combinations of argon and methane samples. These mass spectra show the unambiguous detection of externally generated ions from the plasma in the simulation chamber. In addition, the various spectra show evidence of fragmentation and bond forming reactivity, illustrating the impact of the composition of the plasma.