PHOSPHORUS CRACKING EFFICIENCY AND FLUX TRANSIENTS FROM A VALVED EFFUSION CELL

The transient behavior of the flux from a valved effusion cell contain ing red phosphorus is shown to result from a low elemental sublimation coefficient (alpha=1.3X10(-7)) and not from the presence of white pho sphorus in the sublimator region. The criteria for generating white ph osphorus in the sublimator are given. The conversion from tetramers to dimers is modeled as a function of temperature and pressure. At highe r pressures, higher temperatures are needed to convert P-4 to P-2. Exp erimental results are shown to be in qualitative agreement with result s from thermodynamic equilibrium arguments. (C) 1995 American Institut e of Physics.