Hi! I am a chemist (MSc) working in the field of analytical chemistry. I am using mass spectrometers for years now and I almost have no knowledge about the physical basics. I have read a book about different ion optics, but it was still not deep enough. Could you give me some advice where to look for answers? The things I know: In the quadrupole ion optics there are four parallel rods, the opposing rods on the same potential. This potential is either +(U + V cos (omega t)) or -(U + V cos (omega t)) on the given rods, so the electric field alters in time (the potential is F = [(x^2 - y^2)/r^2]*(U+V cos (omega t)) ), which - to the best of my knowledge - creates a magnetic field of which I have found no information on the web. Then ions are introduced to this field parallel to the axis of the rods, and depending on the mass / charge ratio and the U and V potentials on the rods, some ions will have stable, and others unstable trajectories. How does it really work? Where could I read about this? Thanks for your replies.