One- and Two-Photon Dissociation ofNa2: Angular, Velocity, and Internal-State Distributions of Atomic Fragments Studied by Doppler Spectroscopy

We report on the photodissociation of neutral diatomic molecules in a molecular-beam experiment where all the relevant quantities are well defined. The velocity and angular distributions and the internal states of the fragments were determined by Doppler spectroscopy. The quasibound level $v^{\prime }=31\mathrm{}$, $J^{\prime }=42\mathrm{}$ of the $B{}_{}{}^1{}_{}{}^{}\Pi _{\mathrm{u}}^{}{}_{}{}^{}$ state of ${\mathrm{Na}}_2$ dissociates into ${\mathrm{Na}}^{*}3{}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}$ and $\mathrm{Na}3{}_{}{}^2{}_{}{}^{}S_{\frac{1}{2}}^{}{}_{}{}^{}$ atoms with an angular distribution characterized by $\beta =-1\mathrm{}$. Direct dissociation of the $B{}_{}{}^1{}_{}{}^{}\Pi _{\mathrm{u}}^{}{}_{}{}^{}$ state yields only ${\mathrm{Na}}^{*}3{}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}$ fragments, which does not support reported ${}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}$ and ${}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{}$ fragment emission. From two-photon dissociation we obtain ${\mathrm{Na}}^{*}3{}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{}$ fragments with much larger kinetic energy and a different angular distribution.