High mass resolution SIMS

Abstract We are developing a method to conduct SIMS analysis at high mass resolution (m/Δm>50,000), to facilitate the examination and study of complex organic and biomolecules on surfaces. The approach uses a primary-ion beam probe (rastered 25 keV Ga+ ion source), providing high (100 nm) spatial resolution, and an ion cyclotron resonance (ICR) cell, capable of mass analysis at a resolution in excess of 105 and mass accuracy of less than 1.0 ppm. The apparatus includes a time-of-flight (ToF) mass analyzer, offering rapid chemical mapping at low (m/Δm 300), although, readily detected by the ToF analyzer, are inefficiently transmitted to the ICR cell. This has stimulated the design of a new ion optics coupling arrangement, which provides a higher mass resolution over a wider mass range.