This is the final report of the research performed at ORNL on the chemical fractionation of boron isotopes between BF3 gas and the liquid molecular addition compounds of BF3. Thirty compounds were studied, ten of them in detail. Graphs and equations are given for variation of isotopic equilibrium constant, vapor pressure, and BF3 solubility as a function of temperature. Rate of isotopic exchange and melting points were determined. Several of the compounds are likely candidates for use in a gas-liquid countercurrent exchange system for large-scale separation of boron isotopes. 23 figs, 53 tables, 39 references.

A method of separating boron isotopes .sup. 10 B and .sup. 11 B by laser-induced selective excitation and photodissociation of BCl.sub. 3 molecules containing a particular boron isotope. The photodissociation products react with an appropriate chemical scavenger and the reaction products may readily be separated from undissociated BCl.sub. 3, thus effecting the desired separation of the boron isotopes.

The isotopes of boron, .sup. 10 B and .sup. 11 B, are separated by means of a gas-liquid chemical exchange reaction involving the isotopic equilibrium between gaseous BF.sub. 3 and a liquid BF.sub. 3 . donor molecular addition complex formed between BF.sub. 3 gas and a donor chosen from the group consisting of: nitromethane, acetone, methyl isobutyl ketone, or diisobutyl ketone.