The reaction of metastable Kr with F2 to form KrF excimer is studied using the crossed-molecular-beam technique. An emission spectrum of KrF* is obtained in the 210-265 nm region. The spectrum appreciably differs from a previous one that has been obtained in a flowing afterglow experiment. The vibrational distribution of KrF* formed by the crossed beam is well described by a linear surprlsal distribution with λv = –4.0, while that from the flowing afterglow has been described with λv = –2.5. It is found that vibrational levels with v = 50-90 are highly populated. © 1992 The Japan Society of Applied Physics.