Excitation cross-sections of TiI, ZrI, and HfI spectral lines are meas
ured by the method of extended crossing beams with detection of the op
tical signal from the intersection region. The results of measurements
are used to calculate the excitation cross-sections of the energy lev
els of the D-3(0) states of investigated atoms. For the titanium and z
irconium atoms, the experimental and theoretical values of cross-secti
ons are compared.