The ionization cross-sections of B2O3, NaBO2, NaPO3, and KPO3 were determined by high-temperature mass spectrometry. It is shown that the use of the additivity rule for calculating the ionization cross-sections leads to underestimated partial pressures of the molecular forms of vapor above the objects being studied, even when appropriate correction factors are introduced.
Lopatin et al. (Sun,) studied this question.