Improvements in SIMS continue. Is the end in sight?

Cluster ion bombardment is at the forefront of current ToF-SIMS research, particularly when examining the feasibility of molecular depth profiling and three-dimensional imaging applications. It has become increasingly clear that secondary ion emission after cluster projectile impact results from a radically different sputtering mechanism than the linear collision cascades that dominate after atomic ion bombardment. The new physics involved with cluster ion impacts dramatically change the traditional approaches toward sample analysis with the SIMS technique. Several new ion bombardment properties have emerged from experimental and theoretical work involving cluster ions such as Au ₃ ⁺ , Bi ₃ ⁺ , SF ₅ ⁺ , and C ₆₀ ⁺ -all of which are commercially available ion sources. These new properties lead to new rules for traditional static SIMS experiments, provoking new methodologies, and introducing new applications-especially where high mass sensitivity and high-resolution imaging of organic and biological materials are necessary. This paper aims to elucidate recent experimental and theoretical work on these new cluster ion properties and offers insights into how these special properties can be used for future experiments and applications.