We present the design and the characteristics of an ultrahigh vacuum compatible laser ablation source which can be operated in a crossed molecular beam machine at pressures as low as 10(-9) Torr. This unit provides intense supersonic beams of up to 3 X 10(13) cm(-3) reactant species (carbon atoms, dicarbon, and tricarbon) in the interaction region of a crossed molecular beam machine. Practical delay time windows between the pulsed valve releasing the seeding gas and the laser have been determined to be between 16 630 and 16 645 mu s, i.e., firing the laser 150-165 mu s after the 80 mu s pulsed valve trigger. The concentration of the dicarbon and tricarbon clusters can be maximized/ minimized by adjusting the laser focus (a tighter laser focus leads to an enhanced atomic carbon component) and the laser power (multiphoton dissociation). We achieved stable peak velocities between 800 and 3800 m s(-1) and speed ratios S of up to 6. (c) 2006 American Vacuum Society.