The work of Noid et al. [J. Chem. Phys., 67, 404 (1977)] has shown that sharp molecular spectra can be obtained through a Fourier transform of the autocorrelation function of a classical trajectory. In the present work, we extend this idea to obtain a spectrum by Fourier transform of the dipole moment function of collision product trajectories. We show that this classical collision spectrum (CCS) is related to the cross ...