Experimental observation of H2− anions by high-resolution ESR spectroscopy in γ-ray irradiated quantum solid parahydrogen at 4.2 K

High-resolution ESR spectroscopy by use of quantum solid parahydrogen has been applied to the observation of H2− anions. When solid parahydrogen is irradiated with γ-rays at 4.2 K, H2− anions produced show ESR spectra of quartet lines with a hyperfine splitting constant of 203 G. H2− anions consist of the mixture of p-H2− (25%) and o-H2− (75%), though the concentration of p-H2 in the matrix exceeds 95%. It is suggested that electron bubbles assumed previously in irradiated solid hydrogen are probably the H2− anions observed here.