Microscopic Insights into the Sputtering of Ag{111} Induced by C<sub>60</sub> and Ga Bombardment

Postawa, Zbigniew; Czerwinski, Bartlomiej; Szewczyk, Marek; Smiley, Edward J.; Winograd, Nicholas; Garrison, Barbara J.

doi:10.1021/jp049936a

Cited by 181 publications

(219 citation statements)

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“…For comparison with recent MD computer simulations performed for the same projectiles impinging onto a°(111)°surface°of°an°ideal°Ag°single°crystal° [21],°the°MD data°have°been°included°in°Table°1.°First,°it°is°seen°that the measured yield variations are in qualitative agreement with the simulation. This is particularly true for the impact energy dependence observed under C 60 bombardment, where the experiment detects almost identical°ratios°as°predicted°from°the°simulations° [22].…”

Section: Total Yieldmentioning

confidence: 86%

“…The spike model has traditionally been employed to interpret the response of metallic targets to cluster bombardment [20]. Instead, the emission mechanism is proposed to involve the quasi-free expansion of a super-critically heated subsurface volume.Recent molecular dynamics (MD) computer simulations show a largely different desorption process for isoenergetic Ga and C 60 bombardment [21,22]. For 15 keV Ga bombardment of Ag{111}, atomic motion is described by a classic collision cascade with a desorption yield of about 20 Ag atoms per incident Ga ϩ ion.…”

mentioning

confidence: 99%

“…Recent molecular dynamics (MD) computer simulations show a largely different desorption process for isoenergetic Ga and C 60 bombardment [21,22]. For 15 keV Ga bombardment of Ag{111}, atomic motion is described by a classic collision cascade with a desorption yield of about 20 Ag atoms per incident Ga ϩ ion.…”

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confidence: 99%

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Energetic ion bombardment of Ag surfaces by C₆₀⁺ and Ga⁺ projectiles

Sun

Szakal

Winograd

et al. 2005

J. Am. Soc. Mass Spectrom.

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The ion bombardment-induced release of particles from a metal surface is investigated using energetic fullerene cluster ions as projectiles. The total sputter yield as well as partial yields of neutral and charged monomers and clusters leaving the surface are measured and compared with corresponding data obtained with atomic projectile ions of similar impact kinetic energy. It is found that all yields are enhanced by about one order of magnitude under bombardment with the C 60 ϩ cluster projectiles compared with Ga ϩ ions. In contrast, the electronic excitation processes determining the secondary ion formation probability are unaffected. The kinetic energy spectra of sputtered particles exhibit characteristic differences which reflect the largely different nature of the sputtering process for both types of projectiles. In particular, it is found that under C 60 ϩ impact (1) the energy spectrum of sputtered atoms peaks at significantly lower kinetic energies than for Ga ϩ bombardment and (2) the velocity spectra of monomers and dimers are virtually identical, a finding which is in pronounced contrast to all published data obtained for atomic projectiles. T he elucidation of the mechanism of interaction of energetic polyatomic or cluster ions with surfaces is of current interest since these projectiles are now being extensively employed as desorption probes in secondary ion mass spectrometry (SIMS) experiments [1,2]. Because of their propensity to produce higher molecular ion signals than corresponding atomic ions and the emergence of commercially available C 60 ϩ [3,4] and Au 3 ϩ [5, 6] ion guns, applications have expanded dramatically. For example, these sources can be focused onto the sample with a probe size about 1 micron, allowing greatly improved molecule-specific imaging experiments. The high secondary ion yield associated with the cluster/solid interaction also allows for molecular depth profiling studies without the accompanying damage accumulation normally associated with atomic bombardment [7][8][9][10][11][12][13][14][15][16][17].The mechanisms associated with the observed secondary ion yield enhancement are not yet clear, although details are emerging quickly. A basic question that must be resolved is to determine whether the yield enhancement occurs as a consequence of increased ionization efficiency, or is due to more effective sputtering in the neutral desorption channel. There is mixed information about this point. For In and Ag surfaces, for example, it has been shown that the enhanced secondary ion yield under SF m ϩ bombardment (m ϭ 1-5) largely arises from the enhanced ionization efficiency attributable to implanted F atoms [18]. For organic systems, however, very high removal rates of neutral species have been reported [2], obviating the need to invoke enhancement of the secondary ionization probability. Most recently, yields and velocity distributions were measured for In and In 2 sputtered from In surfaces bombarded with Au ϩ , Au 2 ϩ , and Au 3 ϩ [19]. Although these experiments do not ad...

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Section: Total Yieldmentioning

confidence: 86%

mentioning

confidence: 99%

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Energetic ion bombardment of Ag surfaces by C₆₀⁺ and Ga⁺ projectiles

Sun

Szakal

Winograd

et al. 2005

J. Am. Soc. Mass Spectrom.

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“…It has been demonstrated that these enhanced yields are produced with a concomitant increase in surface damage, but the yield enhancement surpasses that of damage [32]. Many studies have combined to develop the now accepted idea that the lower penetration depth and overlapping collision cascades of the polyatomic primary ion deposit more energy in the surface region, thus leading to increased sputtering [33][34][35][36][37][38][39].…”

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confidence: 99%

Higher sensitivity secondary ion mass spectrometry of biological molecules for high resolution, chemically specific imaging

McDonnell

Heeren

Lange

et al. 2006

J. Am. Soc. Mass Spectrom.

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To expand the role of high spatial resolution secondary ion mass spectrometry (SIMS) in biological studies, numerous developments have been reported in recent years for enhancing the molecular ion yield of high mass molecules. These include both surface modification, including matrix-enhanced SIMS and metal-assisted SIMS, and polyatomic primary ions. Using rat brain tissue sections and a bismuth primary ion gun able to produce atomic and polyatomic primary ions, we report here how the sensitivity enhancements provided by these developments are additive. Combined surface modification and polyatomic primary ions provided Ϸ15.8 times more signal than using atomic primary ions on the raw sample, whereas surface modification and polyatomic primary ions yield Ϸ3.8 and Ϸ8.4 times more signal. This higher sensitivity is used to generate chemically specific images of higher mass biomolecules using a single molecular ion

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“…A number of studies have shown that the sputtering efficiency of secondary ions is improved by increasing the mass of the primary particles. [1][2][3][4][5][6][7][8][9][10][11] Various methods have been reported for the formation of cluster ions as projectiles for cluster secondary ion mass spectrometry (SIMS). Blain et al produced cluster projectiles by 252 Cf-fission fragment-induced desorption.…”

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confidence: 99%

Study on ion formation in electrospray droplet impact secondary ion mass spectrometry

Asakawa

Fujimaki

Hashimoto

et al. 2007

Rapid Comm Mass Spectrometry

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A new type of cluster secondary ion mass spectrometry (SIMS), named electrospray droplet impact (EDI), has been developed in our laboratory. In general, rather strong negative ions as well as positive ions can be generated by EDI compared with conventional SIMS. In this work, various aspects of ion formation in EDI are investigated. The Brønsted bases (proton acceptor) and acids (proton donor) mixed in the analyte samples enhanced the signal intensities of deprotonated molecules (negative ions) and protonated molecules (positive ions), respectively, for analytes. This suggests the occurrence of heterogeneous proton transfer reactions (i.e. M R M( ! [MRH] R R [M(SH] S ) in the shockwave-heated selvedge of the colliding interface between the water droplet and the solid sample deposited on the metal substrate. EDI-SIMS shows a remarkable tolerance to the large excess of salts present in samples. The mechanism for desorption/ionization in EDI is much simpler than those for MALDI and SIMS because only very thin sample layers take part in the shockwave-heated selvedge and complicated higher-order reactions are largely suppressed.

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Microscopic Insights into the Sputtering of Ag{111} Induced by C₆₀ and Ga Bombardment

Cited by 181 publications

References 51 publications

Energetic ion bombardment of Ag surfaces by C₆₀⁺ and Ga⁺ projectiles

Energetic ion bombardment of Ag surfaces by C₆₀⁺ and Ga⁺ projectiles

Higher sensitivity secondary ion mass spectrometry of biological molecules for high resolution, chemically specific imaging

Study on ion formation in electrospray droplet impact secondary ion mass spectrometry

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Microscopic Insights into the Sputtering of Ag{111} Induced by C60 and Ga Bombardment

Cited by 181 publications

References 51 publications

Energetic ion bombardment of Ag surfaces by C60+ and Ga+ projectiles

Energetic ion bombardment of Ag surfaces by C60+ and Ga+ projectiles

Higher sensitivity secondary ion mass spectrometry of biological molecules for high resolution, chemically specific imaging

Study on ion formation in electrospray droplet impact secondary ion mass spectrometry

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Microscopic Insights into the Sputtering of Ag{111} Induced by C₆₀ and Ga Bombardment

Energetic ion bombardment of Ag surfaces by C₆₀⁺ and Ga⁺ projectiles

Energetic ion bombardment of Ag surfaces by C₆₀⁺ and Ga⁺ projectiles