Shock wave mechanism for cluster emission and organic molecule desorption under heavy ion bombardment

Bitensky, I.S.; Parilis, E.S.

doi:10.1016/0168-583x(87)90135-2

Cited by 209 publications

(47 citation statements)

References 55 publications

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“…Several authors have suggested that desorption phenomena produced by various primary particles are caused by purely mechanical forces. Shock wave induced surface "unloading" has been suggested [35][36][37] for both pulsed UV laser and high energy particle impact desorption. While a shock wave probably does not occur in our experimental situation, transient high pressures can be produced by two other mechanisms: i) warming of a semi-trans parent material by a laser on a time scale short with respect to the time necessary for the resulting expan sion to relax with the unirradiated surroundings [38]; and ii) strong localized absorption in an otherwise transparent material at a defect or impurity [39], Both of these mechanisms produce localized high stress fields, which relax by producing strain fields.…”

Section: Discussionmentioning

confidence: 99%

Infrared Desorption of Neutral Molecules Embedded in Transparent Matrices

Beavis

Lindner

Grotemeyer

et al. 1988

Zeitschrift Für Naturforschung A

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I n f r a r e d D e s o r p tio n o f N e u t r a l M o le c u le s E m b e d d e d in T r a n s p a r e n t M a tr ic e s R.C. Beavis, J. Lindner, J. Grotemeyer, and E.W. Schlag Institut für Physikalische und Theoretische Chemie, Technische Universität München Z. Naturforsch. 43a, 1083Naturforsch. 43a, -1090Naturforsch. 43a, (1988; received July 25, 1988 The desorption of intact molecules by pulsed IR irradiation is shown to depend on the IR absorption of the matrix. IR transparent matrices, such as NaCl or NH4N03, increase the total yield and the shot-to-shot stability of the sample. IR absorbing matrices decrease the yield of intact molecules and increase the amount of pyrolysis products.Using semi-transparent sugar matrices with dipeptide samples, the most intense fragment, i.e. the parent molecule having lost 18 u, is suppressed. This fragment is formed by pyrolysis during IR desorption. Three other prominent fragments are caused by the UV photoionization step.The experimental results suggest that a model involving bulk stresses and strain may be necessary to explain the observations.

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Section: Discussionmentioning

confidence: 99%

Infrared Desorption of Neutral Molecules Embedded in Transparent Matrices

Beavis

Lindner

Grotemeyer

et al. 1988

Zeitschrift Für Naturforschung A

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“…On purpose, however, we avoid using our experimental charge-state scalings as a test of the reliability of specific models, because different versions of the same type of model predict different scalings and different types of models (e.g. thermal or hydrodynamical) may predict the same scaling [22,27,28]. A quantitative modeling of the complex process of crater formation by fast atomic projectiles is far from being accomplished.…”

Section: Fig 2 (Color)mentioning

confidence: 99%

Direct Evidence for Projectile Charge-State Dependent Crater Formation Due to Fast Ions

et al. 2008

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We report on craters formed by individual 3 MeV=u Au q ini þ ions of selected incident charge states q ini penetrating thin layers of poly(methyl methacrylate). Holes and raised regions are formed around the region of the impact, with sizes that depend strongly and differently on q ini . Variation of q ini , of the film thickness and of the angle of incidence allows us to extract information about the depth of origin contributing to different crater features. DOI: 10.1103/PhysRevLett.101.167601 PACS numbers: 79.20.Rf, 61.80.Jh, 61.82.Pv, 81.16.Rf Energetic atomic [1-3], molecular or cluster ions [4] impacting solids may leave tiny holes at the surface often surrounded by a raised region of displaced material. The observed surface morphology [1][2][3][4] is similar to what is found in ablation craters produced by an intense laser pulse [5,6], in macroscopic craters produced by meteorite impacts on planets [7], or by balls dropped into granular media [8], although their spatial scales may differ by about 17 orders of magnitude. Depending on the energy regime of the ions and the type of material being bombarded, the shape of the impact features and the underlying mechanisms of formation may differ [9,10]. As the energy deposited by swift ions of equal kinetic energy, but different charge-states may vary substantially close to the surface, a detailed knowledge of charge-state dependent effects is of great importance for ion-beam based techniques of materials structuring (such as ion-track etching), particularly considering the new demands for smaller pattern sizes and the use of thinner layers [11]. Our results give direct evidence for a strong dependence of the surface modifications introduced by single fast ions on their charge state. For track-etching procedures, this means it is possible to control the etching sensitivity at the surface and charge equilibration below the surface should yield different etched shapes, dependent on the incident charge state. Moreover, by employing a series of well-defined nonequilibrium charge states, we could derive depth information on the near-surface effects induced by single fast ion impacts.In this Letter, we focus on cratering induced by high velocity ions. At specific kinetic energies of a few MeV per nucleon, such ions transfer more than 99% of their energy to the target-electron system. A considerable fraction of the energy deposited in the track of a swift heavy ion is concentrated in a core region ( % 1 nm), where ionizations are directly produced by the ions. Fast secondary electrons spread the rest of the energy over larger distances. The exact size of such regions depend on the material and on the velocity of the ions, while the total amount of energy loss per path length, S e ¼ dE e =dx, is well understood [12]. The subsequent electron dynamics, however, is a nonlinear phenomenon and it may result in large sputter yields and cratering, due to the coupling of electronic and atomic degrees of freedom [13][14][15]. For reviews on ion-induced electronic cratering pr...

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“…To interpret these experimental observations [3-l6], it has often been assumed that nonlinear regimes of sputtering described by a shock wave model [7], a thermodynamical model [8], or a collision spike model [9], led to the nonadditivity of the process. However, theoretical models [7][8][9] are not capable of explaining all features of nonadditive sputtering.…”

Section: Introductionmentioning

confidence: 99%

Nonadditive sputtering of silicon by keV energy molecular projectiles of heavy and light elements

Belykh

Kovarsky²,

Palitsin

et al. 2001

International Journal of Mass Spectrometry

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In the present work a positive secondary ion emission from a silicon produced by Au m Ϫ projectiles (m ϭ 1-3) with energies of E 0 ϭ 9 and 18 keV and by Al m Ϫ projectiles (m ϭ 1,2) with energies of E 0 ϭ 6, 9, 12, and 18 keV have been studied. Anomalous high nonadditivity of sputtering as large cluster Si n ϩ ions (n Ͼ 4) under molecular Au m Ϫ ion bombardment has been found. As compared with heavy (Au m Ϫ ) projectiles, the light (Al m Ϫ ) projectiles are not effective for sputtering of large cluster ions. For molecular Al m Ϫ ion bombardment nonadditivity of sputtering of small cluster Si n ϩ ions (n Յ 4) increases with decreasing of the energy E 0 from 9 to 6 keV/atom. This effect shows that the efficiency of nonadditive sputtering strongly depends on the penetration depth of molecular projectile and, hence, on the energy density deposited by molecular projectile into subsurface layers of the target from which the cluster ion emission occurs. (Int J Mass Spectrom 209 (2001) 141-152)

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Shock wave mechanism for cluster emission and organic molecule desorption under heavy ion bombardment

Cited by 209 publications

References 55 publications

Infrared Desorption of Neutral Molecules Embedded in Transparent Matrices

Infrared Desorption of Neutral Molecules Embedded in Transparent Matrices

Direct Evidence for Projectile Charge-State Dependent Crater Formation Due to Fast Ions

Nonadditive sputtering of silicon by keV energy molecular projectiles of heavy and light elements

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