Negative-ion mass spectrometric study of ion-pair formation in the vacuum ultraviolet. IV. CH4→H−+CH+3 and CD4→D−+CD+3

Abstract
Ion‐pair formation from photoexcited methanes, CH*4 →H +CH+3 and CD*4 →D +CD+3, has been studied by measuring the efficiency curves of H and D using synchrotron radiation. Ion pairs are produced both by direct dissociation and predissociation of the npt2 (n=3–5) Rydberg state converging to the à 2A1 state of CH+4/ CD+4. The 4pt2 and 5pt2 Rydberg states are observed here for the first time.