ToF-SIMS Spatially Resolved Molecular Information

ToF-SIMS imaging exhibits remarkable characteristics. For example, by using a 25 keV Ga+ or Bi+ ion LMIG, these instruments can produce spatially resolved images of molecular species with molecular weights of up to several thousand Daltons and with a spatial resolution less than 100 nm [142]. 

as the applications of molecular imaging experiments continue to expand, new variants of the experimental protocol promise further breakthroughs. For example, it is possible to improve the yield of molecular ions by using cluster ion beam sources rather than atomic ion sources [143,144]. Typically, a group of projectile atoms can more efficiently desorb labile molecules with less fragmentation than a single atomic ion [137]. 

Lateral Resolution Before discussing the requirements in more detail, it is worth introducing the concept of the duty cyde. 

When considering a pulsed beam characterized by a pulse width f (ns) and a period j (where/is the repetition rate, s ), the duty cycle (d), defined by the time fraction during which the beam is on, is given by the following equation  

Consequently, if is defined as the time to erode the uppermost monolayer by a continuum beam  

---