A magnet structure or instrument for spectroscopy including a plurality of magnetic flux sources disposed along a common axis. The plurality of permanent magnetic flux sources include a first magnet flux source having a first through-hole body, and include second and third magnet flux sources located respectively on opposite sides of the first magnet flux source, with at least one of the second and third magnet flux sources having a side through-hole body. Magnetic flux within the first magnet flux source is oriented to generate a first magnetic field directed along the common axis. Respective magnetic fluxes within the second and third magnet flux sources are oriented to generate second and third magnetic fields directed along the common axis, with at least one field component of either the second or third magnetic fields along the common axis inside the respective second or third magnet flux sources opposed to a direction of the first magnetic field on said common axis inside the first magnet flux source.