Perturbation effects on lifetimes ofdΠu3states inH2andD2

Abstract

Lifetimes of rovibronic levels of d ${}_{}{}^3{}_{}{}^{}\mathrm{\Pi }_{\mathrm{u}}^{}{}_{}{}^{}$ states in ${\mathrm{H}}_2$ and ${\mathrm{D}}_2$ have been measured by using the electron-impact-excitation and delayed-coincidence method. Observed differences between the lifetimes of ${}_{}{}^3{}_{}{}^{}\mathrm{\Pi }_{\mathrm{u}}^{\mathrm{e}}{}_{}{}^{}$(v,N) and ${}_{}{}^3{}_{}{}^{}\mathrm{\Pi }_{\mathrm{u}}^{\mathrm{f}}{}_{}{}^{}$(v,N) sublevels in ${\mathrm{H}}_2$ were the direct result of perturbations arising from interactions between d ${}_{}{}^3{}_{}{}^{}\mathrm{\Pi }_{\mathrm{u}}^{\mathrm{f}}{}_{}{}^{}$(v,N) and ${}_{}{}^3{}_{}{}^{}\mathrm{\Sigma }_{\mathrm{u}}^{+}{}_{}{}^{}$(v’,N) levels. Different lifetime variation with N of the d ${}_{}{}^3{}_{}{}^{}\mathrm{\Pi }_{\mathrm{u}}^{\mathrm{f}}{}_{}{}^{}$(v,N) states in ${\mathrm{H}}_2$ and ${\mathrm{D}}_2$ implied that several e ${}_{}{}^3{}_{}{}^{}\mathrm{\Sigma }_{\mathrm{u}}^{+}{}_{}{}^{}$ levels were predissociated in ${\mathrm{H}}_2$ but not in ${\mathrm{D}}_2$.