Computer simulations of sputtering and fragment formation during keV C<sub>60</sub> bombardment of octane and <i>β</i>‐carotene

Postawa, Zbigniew; Kański, Michał; Maciążek, Dawid; Paruch, Robert J.; Garrison, Barbara J.

doi:10.1002/sia.5550

Cited by 6 publications

(7 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It appeared later that these effects were both influenced by the mass of the projectile atoms . Recently, Postawa et al also studied the sputtering of organic solids with two different molecular weights, n -octane (114 amu) and β-carotene (537 amu), and they found almost no difference of sputtered quantities . This observation seemed at odds with some of the experimental SIMS literature and with our own simulations comparing kDa chains with virtually infinite polymers .…”

Section: Introductionmentioning

confidence: 65%

“…A recent atomistic MD study of C 60 bombardment of organic materials investigated the molecular size effect to some extent by comparing the sputtering of octane and β-carotene from their molecular solids. 38 Octane is about two times smaller than PE282 while β-carotene is about 2 times larger. Despite the differences in the models and in the samples, a similar conclusion was drawn in their study, i.e., that the total sputter yield was comparable for the two samples at a given projectile energy and that the ratio of intact molecules to fragments was larger for the smaller molecules.…”

Section: ■ Results and Discussionmentioning

confidence: 89%

“…37 carotene (537 amu), and they found almost no difference of sputtered quantities. 38 This observation seemed at odds with some of the experimental SIMS literature 39 and with our own simulations comparing kDa chains with virtually infinite polymers. 40 Therefore, we felt that this point required complementary investigation with intermediate size samples.…”

Section: ■ Introductionmentioning

confidence: 71%

Section: Results and Discussionmentioning

confidence: 99%

See 3 more Smart Citations

Macromolecular Sample Sputtering by Large Ar and CH₄ Clusters: Elucidating Chain Size and Projectile Effects with Molecular Dynamics

Delcorte

Debongnie

2015

J. Phys. Chem. C

View full text Add to dashboard Cite

This article reports the latest developments of our theoretical studies of gas cluster bombardment of model macromolecular samples using molecular dynamics simulations. Here, we perform a detailed comparison of the effects of the sample molecular weight, the Ar cluster incidence angle (45° vs 0°), and the cluster nature (CH4 vs Ar) on the soft sputtering of polymeric samples. The results of Ar cluster-induced sputtering and fragmentation at 45° incidence for molecular targets with three different molecular weights (282, 1388, and 14002 amu) indicate a pronounced influence of that parameter beyond 1000 amu, which is explained by the extra energy needed to form fragments from longer chains and to overcome mechanical entanglement. An excellent agreement is found between the computed statistics of sputtering and the available experimental data for similar molecular weights. The variance of the sputtering and polymer fragmentation results with changing beam parameters is explained via the microscopic analysis of the interaction in the simulations. The influential physical quantities are identified, namely, the energy (density) deposited in the impact region, the projectile velocity, and the geometry of the impact. The lower sputtering efficiency of CH4 molecular clusters results mainly from the extra energy spent in covalent bond-breaking and vibrational excitation of the cluster constituents.

show abstract

Section: Introductionmentioning

confidence: 65%

Section: ■ Results and Discussionmentioning

confidence: 89%

Section: ■ Introductionmentioning

confidence: 71%

Section: Results and Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Macromolecular Sample Sputtering by Large Ar and CH₄ Clusters: Elucidating Chain Size and Projectile Effects with Molecular Dynamics

Delcorte

Debongnie

2015

J. Phys. Chem. C

View full text Add to dashboard Cite

show abstract

“…The simulations have been applied on more complicated materials including organic molecules by development of interatomic potentials [50][51][52]. The analysis on chemical components revealed that cluster impact shows less fragmentation in sputtering and crosslinking in the target, which probes the advantages in precise measurement and depth profiling of XPS and SIMS of organic materials.…”

Section: Computer Simulation For Cluster Impactsmentioning

confidence: 99%

Progress and applications of cluster ion beam technology

Yamada

Matsuo

Toyoda

et al. 2015

Current Opinion in Solid State and Materials Science

View full text Add to dashboard Cite

Seduction of Finding Universality in Sputtering Yields Due to Cluster Bombardment of Solids

2015

Self Cite

View full text Add to dashboard Cite

Universal descriptions are appealing because they simplify the description of different (but similar) physical systems, allow the determination of general properties, and have practical applications. Recently, the concept of universality has been applied to the dependence of the sputtering (ejection) yield due to energetic cluster bombardment versus the energy of the incident cluster. It was observed that the spread in data points can be reduced if the yield Y and initial projectile cluster kinetic energy E are expressed in quantities scaled by the number of cluster atoms n, that is, Y/n versus E/n. The convergence of the data points is, however, not perfect, especially when the results for molecular and atomic solids are compared. In addition, the physics underlying the apparent universal dependence in not fully understood. For the study presented in this Account, we performed molecular dynamics simulations of Arn cluster bombardment of molecular (benzene, octane, and β-carotene) and atomic (Ag) solids in order to address the physical basis of the apparent universal dependence. We have demonstrated that the convergence of the data points between molecular and atomic solids can be improved if the binding energy of the solid U0 is included and the dependence is presented as Y/(E/U0) versus (E/U0)/n. As a material property, the quantity U0 is defined per the basic unit of material, which is an atom for atomic solids and a molecule for molecular solids. Analogously, the quantity Y is given in atoms and molecules, respectively. The simulations show that, for almost 3 orders of magnitude variation of (E/U0)/n, there are obvious similarities in the ejection mechanisms between the molecular and atomic solids, thus supporting the concept of universality. For large (E/U0)/n values, the mechanism of ejection is the fluid flow from a cone-shaped volume. This regime of (E/U0)/n is generally accessed experimentally by clusters with hundreds of atoms and results in the largest yields. For molecular systems, a large fraction of the total energy E is consumed by internal excitation and molecular fragmentation, which are energy loss channels not present in atomic solids. For small (E/U0)/n values, the cluster deforms the surface and the ejection occurs from a ring-shaped ridge of the forming crater rim. This regime of (E/U0)/n is generally accessed experimentally by clusters with thousands of atoms and results in the smallest yields. For the molecular systems, there is little or no molecular fragmentation. The simulations indicate, however, that the representation which includes U0 as the only material property cannot be completely universal, because there are other material properties which influence the sputtering efficiency. Furthermore, neither the Y/n nor Y/(E/U0) representation includes the energy loss physics associated with molecular fragmentation in the high (E/U0)/n regime. The analysis of the universal concept implies for practical applications that if the objective of the experiment is large material removal, then the...

show abstract

Computer simulations of sputtering and fragment formation during keV C₆₀ bombardment of octane and β‐carotene

Cited by 6 publications

References 19 publications

Macromolecular Sample Sputtering by Large Ar and CH₄ Clusters: Elucidating Chain Size and Projectile Effects with Molecular Dynamics

Macromolecular Sample Sputtering by Large Ar and CH₄ Clusters: Elucidating Chain Size and Projectile Effects with Molecular Dynamics

Progress and applications of cluster ion beam technology

Seduction of Finding Universality in Sputtering Yields Due to Cluster Bombardment of Solids

Contact Info

Product

Resources

About

Computer simulations of sputtering and fragment formation during keV C60 bombardment of octane and β‐carotene

Cited by 6 publications

References 19 publications

Macromolecular Sample Sputtering by Large Ar and CH4 Clusters: Elucidating Chain Size and Projectile Effects with Molecular Dynamics

Macromolecular Sample Sputtering by Large Ar and CH4 Clusters: Elucidating Chain Size and Projectile Effects with Molecular Dynamics

Progress and applications of cluster ion beam technology

Seduction of Finding Universality in Sputtering Yields Due to Cluster Bombardment of Solids

Contact Info

Product

Resources

About

Computer simulations of sputtering and fragment formation during keV C₆₀ bombardment of octane and β‐carotene

Macromolecular Sample Sputtering by Large Ar and CH₄ Clusters: Elucidating Chain Size and Projectile Effects with Molecular Dynamics

Macromolecular Sample Sputtering by Large Ar and CH₄ Clusters: Elucidating Chain Size and Projectile Effects with Molecular Dynamics