  We present an efficient method to produce laser-triggered proton pulses below
500\,ps pulse width at keV energies. We use femtosecond photoelectron pulses
emitted from a cathode to enable ultrafast electron-stimulated desorption of
adsorbates on a stainless steel plate under ultrahigh vacuum conditions. While
direct photoionization of atoms to form well-timed ion pulses can suffer from a
laser-focus-limited large starting volume, in our method the starting plane of
the ions is defined with nanometer precision at a solid surface. We clearly
outline how the method could be used in the future to efficiently produce ion
beam pulses in the (sub-)picosecond range for pump-probe experiments with ions.
