Knudsen cell mass spectrometric investigation of the B2N molecule

High-temperature Knudsen cell mass spectrometry has been used to study the equilibria involving the B2N molecule over the Si-BN system. Thermal functi ons needed in the evaluation of the mass spectrometric equilibrium data hav e been calculated from available experimental and theoretical molecular par ameters. The enthalpy changes for the reactions 2B(g)+Si2N(g)=B2N(g)+2Si(g) , and BN(s)+B(g)=B2N(g) have been measured. The following atomization entha lpy, Delta H-a(0)o, and enthalpy of formation, Delta H-f(298.15)o, in kJ mo l(-1), of 1045.5 +/- 18 and 551.3 +/- 18 for the B2N molecule have been det ermined from these reaction enthalpies. Atomization energies of similar mol ecules have been compared and discussed. (C) 2000 American Institute of Phy sics. [S0021-9606(00)01044-8].