In order to obtain high concentration of IF(B) through chemical ways, we studied the chemiluminescent reactions of F~2, F with I~2 in the flowing afterglow apparatus. Strong emission spectrum IF(B-X) was firstly observed in the F/I~2 system. Simple collision theory was used to estimate the IF(B) vibrational energy relaxation in inert gas. The vibrational population distribution of the excited state IF(B) was measured. Compared the IF(B) vibrational distribution of different systems, we conclude that IF(B) were produced through different reaction mechanisms in the reactions of F~2, F with I~2. The former proceeds via a secondary, reactive encounter of the F atom with the stable thrialogen intermediate I~2F, whearas the latter may be the recombination reaction of spin-orbit excited iodine atoms with ground fluorine atoms.

Key words: CHEMILUMINESCENCE REACTION, FLUORINE, IODINE, CHEMICAL LASER, MEDIA, EMISSION SPECTROGRAPHIC ANALYSIS, VIBRATION RELAXATION, REACTION MECHANISM