A new molecular electronic band system has been observed by laser fluorescence excitation in a free-jet supersonic expansion of photolyzed trimethylaluminum diluted in seed gases containing molecular nitrogen. The overwhelming majority of observed bands displayed the rotational structure of a (1)Pi<--(1)Sigma transition. The change in the rotational constant B " of a band at 36 389 cm(-1), assigned as the origin band, upon N-15 substitution was consistent with the assignment of the molecular carrier as AlNC, and the value of B " for the (AlNC)-N-14((X) over tilde (1)Sigma(+)) isotopomer agreed with that previously determined by pure rotational spectroscopy. To carry out a vibrational assignment, resolved emission spectra were recorded for excitation of the ten strongest bands. With one exception, all these bands were found to involve excitation out of the ground vibronic level. Vibrational quantum numbers for the upper levels were assigned for most bands, and the upper state appears to be linear, with (1)Pi, symmetry. A band at 28 754 cm(-1), assigned to AlNC by Fukushima [Chem. Phys. Lett. 283, 337 (1998)], was also investigated. The lower-state vibrational spacings in its resolved emission spectrum were different than for the bands discussed above. Based on the rotational constants determined in a rotational analysis of this band, the molecular carrier of this transition is assigned as the isomer AlCN.