Competition among autoionization predissociation and ion-pair formation in molecular hydrogen

摘要

Abstract: investigated autoionization, predissociation, and ion- pair formation from highly excited states of molecular hydrogen by using double-resonance excitation via the E, F $+1$/$Sigma$- g$/$+$PLU$/, v $EQ 6 level. The energetic threshold for ion-pair formation occurs just below the H$-2$/$+$PLU$/ X $+2$/$Sigma$- g$/$+$PLU$/, v$+$PLU$/ $EQ 9 ionization threshold. The spectrum in this region was studied by using conventional and constant- ionic-state photoelectron spectroscopy, by monitoring the H$+$MIN$/ production, and by detecting dissociation products by ionization with a third laser. The decay dynamics in this region are extremely rich, because the excited levels may decay by rotational and vibrational autoionization, by predissociation to neutral H $PLU H$+*$/ (n $EQ 2, 3, 4), by predissociation to the ion pair H$+$PLU$/ $PLU H$+$MIN$/, and by fluorescence. In addition, the dissociative potential curve of the 2p$sigma$- u$/3s$sigma$-g$/ $+1$/$Sigma$-u$/$+$PLU$/ doubly excited electronic state crosses the H$-2$/$+$PLU$/ X $+2$/$Sigma$- g$/$+$PLU$/ potential curve in the same energy region, and the electronic autoionization of this state is found to significantly influence these decay processes. !15