  An ultra-cold molecular plasma with extraordinarily long lifetime (~0.5 ms)
is generated under strong collisional cooling conditions in the expansion
region of a seeded supersonic jet expansion close to the nozzle. A resonant
two-photon one-color laser process excites para-difluorobenzene molecules into
the high-n Rydberg threshold region. Disorder heating during plasma formation
is quenched by the high collision rate in the expansion, which keeps the ions
at the translational jet temperature of 0.2K-0.7K. The Coulomb coupling
parameter \Gammai for the ions is expected to be ca. 230-820.
