LASER [2+1] REMPI DETECTION OF BR ATOMS IN UNIMOLECULAR DECOMPOSITIONREACTIONS

A [2 + 1] REMPI detection of Br atoms produced in the IR MPD of (CF3)3 CBr has been fulfilled. It has been shown that IR MPD of (CF3)3CBr res ults in formation of Br atoms mainly in the ground state. High sensiti vity of the Br detection method used has been shown (about 20 atoms in the volume of the probe radiation). The magnitudes of cross sections for the two-photon transition (5p P-4(3/2)0 <-- 5p P-2(3/2)0) alpha = (1.5 +/- 0.6) x 10(-44) cm4 s and subsequent ionization sigma = (2.8 /- 1.2) x 10(-18) cm2 have been determined from the data received. The developed Br atom detection technique was applied to study (CF3)3CBr unimolecular decay under IR MP excitation.