Observation of unexpected energy levels in molecular hydrogen and ortho-para energy transfer

We report the observation of eight unexpected energy levels close to but clearly different from H{sub 2} {ital B} {sup 1}{Sigma}{sub {ital u}}{sup +} levels. In transitions involving these levels vacuum-ultraviolet transitions terminating in p-H{sub 2} levels are observed subsequent to two-photon {ital Q}(1) excitation {ital X}{sup 1}{Sigma}{sub {ital g}}{sup +}({ital v}{prime}{prime}=0){r arrow}{ital EF} {sup 1}{Sigma}{sub {ital g}}{sup +}({ital v}{prime}=6) of o-H{sub 2}. Several findings indicate that these strange levels may be a manifestation of electronically excited H{sub 4}, which has been discussed in a number of theoretical contributions.