[en] With a view to separating isotopic bromine by the use of the laser, the absorption spectrum of bromine molecules, ¹Σ(0⁺g) (ground level) → ³PI(0⁺u) (predissociation level), was measured by the tunable dye laser and isotope shifts were observed. The molecules selectively excited by the irradiation of the dye laser were predissociated and reacted with hydrogen iodide (HI) to give hydrogen bromide (HBr). The obtained over-all maximum separation factor was 1.02. If the quantity of HBr produced by the dark reaction was subtracted from that of total HBr product, the maximum separation factor is 1.15. This is almost in agreement with the separation factor 1.2 estimated from the limited line width of the laser. (auth.)