Ion beams are a powerful tool to study atoms and molecules in the gas phase. We use them to induce dynamics within time scales from the regime of a few femto seconds down to zepto seconds, tunable by the ion velocity.

	Slow Collisions In slow collisions, when the speed of the ion is small with respect to the electron velocity in the orbital under investigation a transient molecule is formed and broken in the collision and the evolution of the electron cloud can be watched.
	Fast Collisions At intermediate velocities, when the ion is a few times faster than the electrons it can be used to rip off electrons in a capture reaction or to knock off electrons in a few body collosion.
	Relativistic Collisions At very high velocities the ion induces a half cycle pulse shorter than an attosecond. The equivalent light field seen by the target reaches easily 1019W/cm2 and virtual photon energies up to keV.
	Dissociative Collisioins The fragmentation of molecules following the collision with atoms allows investigating effects related to the spatial arrangement of the molecular constituents.