The Raman Spectra of Boron Trifluoride, Trichloride, and Tribromide. The Effect of the Boron Isotopes

The Raman frequencies v1{1}, 2v2{2}, v3{2}, and v4{2} for BF3(g), BCl3(l), and BBr3(l) were found to be 886 and 783, 1394, 1038 and 1105, 440; 471, 924, 958 and 996, 243; 279, 743, 806 and 846, and 151 cm—1, respectively. The assignment of frequencies was determined by polarization experiments on BCl3 and is confirmed for the three compounds by the results of a normal coordinate treatment. The doubling of v1 in BF3 is ascribed to vibrational resonance between v1 and 2v4. The doubling of v3 in all three compounds is shown to be due to the presence of the two isotopes of boron B10 and B11. A satisfactory assignment of the infrared frequencies of BCl3 is made