Experimental Evidence of an Interference between Photodissociation Continua

The two states ${}_{}{}^1{}_{}{}^{}\Sigma _u^{}{}_{}{}^{+}$ $B$ and $B^{\prime }$ of ${\mathrm{H}}_2$, dissociating adiabatically to $\mathrm{H}\mathrm{}\left(2p\right)+\mathrm{H}\mathrm{}\left(1s\right)\mathrm{}$ and $\mathrm{H}\mathrm{}\left(2s\right)+\mathrm{H}\mathrm{}\left(1s\right)\mathrm{}$, respectively, are simultaneously excited by vacuum-ultraviolet photon absorption, above threshold. The combination of the coherent excitation of the two continua and of a nonadiabatic transition occurring at large internuclear distance produces a quantum interference effect in the partial photodissociation cross section which strongly affects the branching ratio $\frac{{\sigma }_p({\mathrm{H}}_2\to \mathrm{H}\mathrm{}(2p)+\mathrm{H}\mathrm{}(1s\left)\right)}{{\sigma }_s({\mathrm{H}}_2\to \mathrm{H}\mathrm{}(2s)+\mathrm{H}\mathrm{}(1s\left)\right)}$. Comparisons with theoretical predictions are presented and discussed.