The emission spectra from the reactions of C2H5I, C4H9I and CH2I2 with active nitrogen are observed in a flowing afterglow reactor. The experimental results show that these reactions exhibit identical chemiluminescence characteristics. Thirty-five spectral peaks in the 620-840 nm wavelength range are assigned to vibrational transitions of the NI(b(1)Sigma(+), upsilon' = 0 similar to 6 -> X-3 Sigma(-)) band system. This is the first experimental evidence for the generation of excited state NI(b(1)Sigma(+)) via chemical reactions in the gas phase. The possible formation mechanism of the electronically excited NI(b(1)Sigma(+)) is proposed to be the reaction of N((2)p) in active nitrogen with C2H5I, C4H9I, and CH2I2. (c) 2006 Elsevier B.V. All rights reserved.