Rydberg Matter clusters of hydrogen (H2)N∗ with well-defined kinetic energy release observed by neutral time-of-flight Original Research Article

Neutral Rydberg Matter clusters of hydrogen (H2)N∗ are studied using laser fragmentation neutral time-of-flight measurements outside a K impregnated iron oxide emitter in ultrahigh vacuum. A ns pulsed dye laser beam passing in front of the emitter releases the clusters by Coulomb explosions in the Rydberg Matter cloud surrounding the emitter. Well-resolved cluster peaks are observed, and the kinetic temperature of the clusters is low and well described by T/N, where T is the emitter temperature and N is the number of H2 molecules in the cluster. The clusters are neutral as verified by applying a negative voltage of a few V to the emitter, with no change in the flight times. The clusters receive a common excess kinetic energy of ⩽1 eV in the Coulomb explosions initiated by the laser pulse. The common excess kinetic energy shows that the clusters come from larger clusters or clouds with a large inertia. The sharp time-of-flight peaks show that the bonds in the Rydberg Matter broken by the laser are in just one specific quantum number state, n=3–7. The observed excess energy increases with laser intensity, and the fragmentation pattern changes simultaneously.