Provided are MALDI ion sources, methods of forming ions and mass analyzer
systems. In various embodiments, provided are MALDI ion sources configured to irradiate
a sample on a sample surface with a pulse of laser energy at angle within 10 degrees
or less of the surface normal, and a first ion optics system configured to extract
sample ions in a direction within 5 degrees or less of the surface normal. In various
embodiments, MALDI ion sources having substantially coaxial sample irradiation
and ion extraction are provided. In various embodiments, methods are provided,
which produce sample ions by MALDI and extract sample ions using an accelerating
electrical field to form an ion beam, such that, the angle of the trajectory at
the exit from the accelerating electrical field of sample ions substantially at
the center of the ion beam is substantially independent of sample ion mass.