A study Of collisional and radiative energy transfers between the electronic states of NiF has made possible the determination of the relative positions of most of the electronic states involved in the already rotationally analyzed bands. The presence of three lower 2PI, 2DELTA, and 2SIGMA states is now precisely determined. This experimental work is in good agreement with a recent theoretical study (P. Carette, C. Dufour, and B. Pinchemel, J. Mol. Spectrosc. 161, 323, 1993). (C) 1994 Academic Press, Inc.