Vibrational progressions in the A'-->X(v") fluorescence of ClF in Ar and Kr matrices with 1 <v"<9 are observed in the spectral range from 600 to 900 nm with lifetimes of 141 ms. Two-photon excitation leads to emission from the ionic D' state to the A', 2 (3)Pi (2), and 2 (3)Delta (2) valence states in the range from 390 to 470 nm with 50 ns lifetime. Ground state parameters omega (e) and omega (e)x(e) as well as T-e values for the A(') and D-' states are derived. Matrix and Stokes shifts are observed and the large linewidth of the D-' emission is related to the strong coupling of the ionic state to the lattice. Dissociation quantum efficiencies of 5% and 4.8% are determined for kinetic energies of the F fragment of 0.92 eV and 0.39 eV in Ar (19 K), respectively. (C) 2001 American Institute of Physics.