Collisional energy loss in cluster surface impact: Experimental, model, and simulation studies of some relevant factors

Abstract

Measurements of the collisional energy transfer of size and energy-selected ammonia cluster ions (NH3)nH+, n=1–10, impacting a silicon wafer coated with p-type diamond film are reported. The transfer from translational energy of the incident cluster ions to kinetic energy of intact scattered cluster ions has been studied as a function of impact energy, surface composition, and size of the impinging cluster cations. For low impact energies (<2.5 eV/molecule), cluster ions scattered off the target surface lost most of their initial kinetic energy, while for higher impact energies the elasticity of the cluster–surface collision is surprisingly high: Typically 75% of the impact kinetic energy is retained by the scattered parent clusters. Larger cluster ions are scattered less elastically and a large fraction of them shatter to small(est) fragments. The molecular dynamics simulations examine the two energy disposal regimes, deep inelasticity and shattering. Deep inelastic scattering occurs already below the lowest impact energies probed by the experiment. At higher collision energies, the energy loss continues to increase but a point is reached where most clusters shatter. Those few clusters that rebound intact have lost a disproportionately low fraction of their initial energy. The simulations also explore the cluster size effects, the role of the attraction to the surface, and the importance of the anisotropic forces between the molecules in the cluster. The experimental results and the simulations are discussed using the hard cube model with special reference to collective effects.

Collision-induced fragmentation and neutralization of methanol cluster cations

“…This measurement is accomplished by a mass-specific integration of transmitted ions as a function of the retarding voltage of the analyzer. As has been shown previously [39], the measured data can be fitted accurately to an error function, which corresponds to a Gaussian energy distribution of the beam. The Gaussian maximum is taken as the mean kinetic energy of the ions.…”

Fabrication and Physical Properties of Mono- and Multilayer Metallic Nanostructures

“…Тому для таких досліджень фі-ксація нанокластерів за кімнатної температури була б більш сприятливою. Авторами у роботі [70] детально описано експери-ментальне, теоретичне та чисельне дослідження процесів втрати ОДЕРЖАННЯ ТА ВЛАСТИВОСТІ МОНО-ТА БАГАТОШАРОВИХ НАНОСТРУКТУР 249 енергії для кластерів йонів аміяку, які стикаються з поверхнею тонкої плівки алмазу. Згідно з дослідженням при енергії падаю-чого випромінювання менше 1 еВ процес дисипації енергії клас-терів аміяку знаходиться в «режимі непружности» в тому сенсі, що велика частина початкової кінетичної енергії втрачається на внутрішнє збудження кластерів.…”

Mechanically induced generation of highly reactive excited-state oxygen molecules in cluster scattering

“…[7][8][9] This concept known as the "chemistry with a hammer" 10 may be a promising approach for rendering multicenter reactions with large activation barriers feasible. 2,3,7,8,11 For example, the mechanically induced "burning of air" reaction N 2 + O 2 → 2NO was predicted theoretically more than a decade ago. 8 However, no direct experimental evidence has been reported for this reaction to date, and a better understanding of the energy transfer mechanisms during cluster scattering may be required to predict optimal experimental conditions for such a reaction.…”