The gaseous mixed dimers NaDyBr4 and NaDyI4 and the bromo-iodide species DyBrI, DyBr2I, DyBrI2, NaDyBr3I, NaDyBr2I2, and NaDyBrI3 were generated in an effusion cell reactor at elevated temperatures using several different source configurations and were identified by mass spectrometry. A number of gaseous equilibria involving these species were studied, and thermochemical properties were derived with the aid of thermal functions based on estimated molecular constants. Enthalpies of formation of NaDyBr4 and NaDyI4 are compared with values in the literature, while results for the bromo-iodides are in close accord with values interpolated from data on the pure metal bromides and iodides.

The mole fractions of AgBr and Ag3Br3 in the saturated vapor at 840 K have been evaluated from the vapor mass spectrum, by comparison with the corresponding spectrum of AgCl vapor, where the monomer/trimer ratio is known accurately from vapor molecular weight measurements. Combination of these results with new measurements of the vapor pressure of molten AgBr by the torsion-effusion method in the range 805-936 K yielded the third law enthalpies of vaporization and the standard enthalpies of formation DeltafH degrees 298(AgBr, g) = 27.8 +/- 0.3 kcal mol(-1) and DeltafH degrees 298(Ag3Br3, g) = -19.0 +/- 1 kcal mol(-1). The dissociation energy, D degrees 0(AgBr), is found to be 66.4 +/- 0.3 kcal mol(-1), or 2.88 +/- 0.01 eV, some 3.5-5 kcal mol(-1) lower than previous literature values. Approximate thermochemical stabilities of the dimer species Ag2Cl2 and Ag2Br2 have also been evaluated.