MOLECULAR-BEAM FLUX MEASUREMENTS AND EQUILIBRIA FOR AS-4, P-4, AS-2, P-2 AND ASP

The dynamic equilibrium between P-2, As-2 and AsP at 1000 degrees C ha s been studied by mass spectrometry of fluxes from a double effusion c ell. From simple ion gauge measurements of heated and unheated fluxes we determined the ionization efficiency for the dimers P-2 and As-2 re lative to the tetramers, P-4 and As-4. Simultaneous mass spectrometer and ion gauge measurements of the effusion fluxes allowed the relative ionization sensitivities for P-2, As-2, and AsP to be determined. Fro m the mass spectrometry data it was possible to determine the equilibr ium constant 1.9+/-0.4 and free energy -0.55 eV molecule(-1) for the p rocess As-2+P-2 double left right arrow 2 AsP. (C) 1995 American Insti tute of Physics.