Observations of H3− and D3− from dielectric barrier discharge plasmas

This work reports the reliable experimental observations of the simplest negative triatomic ions, H3− and D3− anions, the stability of which has been debated for several decades, from dielectric barrier discharge hydrogen and deuterium plasmas. The observed H3− and D3− mass signals with widely distributed kinetic energies, from a few eV to ∼100 eV, are contributed from their ground states with lifetimes greater than 8–35 μs. The agreement between theoretical and experimental results for H3− has been reached. The three-body collision process is proposed to be the dominant formation mechanism for the H3− and D3− anions.