Molecular dynamics study of metal‐organic samples bombarded by kiloelectronvolt projectiles

Abstract

In recent experiments involving metal-assisted secondary ion mass spectrometry (MetA-SIMS), either an increase or a decrease of the sputtered organic ion yield was demonstrated depending whether the incoming projectile was atomic (Ga, In) or polyatomic (Bi 3 , C 60 ). Theoretically, the electronic and molecular processes governing the yield variation are still poorly understood for metal-organic surfaces. To unravel the physics of sputtering, molecular dynamics simulations involving metal-organic samples have been implemented. Two targets mimicking, respectively, a gold/organic vertical interface and a molecular sample covered by gold nanoparticles were designed and bombarded with several projectiles, including Ga and C 60 . The results emphasize the differences of emission and molecular mechanisms induced by these projectiles and explain some of the effects observed in MetA-SIMS.

Cluster impacts in organics: microscopic models and universal sputtering curves

“…Additional details about the sample potential parameters can be found in Hamraoui and Delcorte . All the projectiles, *Ga, Bi n , *C 60 , Au 400 , Ar n and (C x H y ) n , were aimed at the surface with a normal incidence. In the set of simulations involving *Ga and *C 60 bombarding sample C, the atomic mass of the projectile was artificially varied (hence, the ‘*’ before the atomic symbol) to specifically investigate the influence of this physical parameter .…”

Cluster SIMS of Organic Materials: Theoretical Insights

“…54,55 These results were quite puzzling at first and MD simulations were conducted using a crystalline polyethylene (PE) sample covered by gold nanoparticles to unravel the effects of the metal overlayer on the dynamics of sputtering. 56,57 The impacts of 10 keV Ga and C 60 with a Au 555 nanoparticle adsorbed on crystalline PE are analyzed in Figure 2.13. Figure 2.13a shows that upon Ga bombardment, the sputtered PE mass increases when the impact point is moved from the bare polymer to the center of the nanoparticle.…”

“…13 Hybrid metal-organic samples 56,57. Projectile impacts on a crystalline polyethylene covered with gold nanoparticles.…”

“…57 (b, c) Snapshots of the impacts of 10-keV Ga and C 60 on the central Au nanoparticle (Au 555 ). Color coding: orange is for the atoms of the central cluster, green and violet are for the Au and PE atoms that are ejected at 30 ps, yellow and cyan are for the remaining Au and PE atoms, and red is for the projectile 56. Recreated from Restrepo et al,56,57 with permission from Wiley.…”

Surface Analysis of Organic Materials with Polyatomic Primary Ion Sources

“…2.21). 128 Briefly, when an atomic ion impinges upon a gold or silver nanoparticle, it creates a collision cascade in the nanoparticle. The resulting energy of the bombarded nanoparticle is then transferred directly into the polymer surface, creating a dense collision cascade in the polymer surface region and enhancing the sputtering yield of the polymer.…”