RYDBERG MATTER - A LONG-LIVED EXCITED-STATE OF MATTER

The theory of condensed excited matter, the so-called Rydberg matter ( RM), is examined briefly. Explicit results are given for several physi cal quantities, notably, the work function and the resistivity, for wh ich experimental results exist. The most important aspects of the expe riments, which are fully described elsewhere, are discussed. Large den sities of Rydberg species are formed in the experiments with cesium va por in contact with carbon (graphite) surfaces. The resistivity of the RM formed is found to be 10(-2)-10(-3) Ohm.m under varying conditions , while theory gives the order of 10(-3) Ohm.m. The work function is e xperimentally found to be less than 0.7 eV, perhaps even less than 0.5 eV. Two different methods were used to extract this quantity from the rmionic diode data. These work function values are much lower than rep orted for any known material, especially at the high temperatures, and they thus give strong support for the description of RM as a very dil ute metal. Theory gives values ranging from 0.6 down to 0.2 eV, depend ing on the principal quantum number, which is estimated to be n=12-14 from the lifetime calculations and from the known pressure. Supporting evidence is found from spectroscopic studies of RM, from jellium calc ulations, and from recent confirming experiments. From the good agreem ent between theory and experiment we conclude that RM exists. (C) 1997 American Institute of Physics.