Collisions of polyatomic ions with surfaces

Cooks, R. Graham; Ast, T.; Mabud, Md.A.

doi:10.1016/0168-1176(90)85077-f

Cited by 305 publications

(259 citation statements)

References 83 publications

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“…As discussed previously, low-energy scattering samples only the top layers of the molecular solid. 31 However, the presence of AA species on the surface layers is evident in the spectra. The effect of ASW thickness in the intermixing process has been checked by increasing the ASW overlayers.…”

Section: Resultsmentioning

confidence: 99%

“…This is an alternative to secondary ion mass spectrometry (SIMS) and is also known as low-energy sputtering (LES) or chemical sputtering. 31 In this hyper-thermal energy process, charge exchange between the ion and the surface occurs upon the collision of the projectile ions in the energy range of 10-100 eV and surface species are released as ions or neutrals. When reactive ions are used, ion-surface reactions also occur.…”

Section: Introductionmentioning

confidence: 99%

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Interaction of Carboxylic Acids and Water Ice Probed by Argon Ion Induced Chemical Sputtering

Cyriac

Pradeep

2008

J. Phys. Chem. C

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In this paper, we investigated the interaction of simple carboxylic acids, formic acid (FA), acetic acid (AA), and propionic acid (PA) with thin layers of water ice in the temperature range of 110-190 K in ultrahigh vacuum. The focus, however, is on the AA-ice system. Molecularly thin layers of these systems were prepared on a pre-cooled polycrystalline copper substrate. The interactions and phase changes in the system were monitored with chemical sputtering using low-energy (e30 eV) Ar + , which probes the topmost surface layers. At 110 K, the deposited AA exists as dimers in its amorphous solid form. At the same temperature, in the presence of water ice, this dimeric form gets converted to chainlike oligomers. Chemical sputtering spectra show distinct features for these two surface species. The data suggest that ion formation reflects the surface structure, implying a unique mechanism for its formation. Detailed studies have been made with amorphous solid water (ASW) and crystalline water (CW) to get a complete understanding of the system. Experiments carried out with AA-D 2 O ice confirmed the proton-transfer mechanism during chemical sputtering. Other studies were conducted with AA-CH 3 OH and AA-CCl 4 systems. Detailed investigations performed to understand the effect of thickness of AA and ice overlayers suggest that the extent of water molecules required to effect the structural transformation in the acid is dependent on the amount of the latter. Dimeric-to-oligomeric transformation does not occur for the PA-ice system. Detection of a structural transition at the very top of ice in molecularly thin films adds additional capabilities to the low-energy ion scattering technique.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Interaction of Carboxylic Acids and Water Ice Probed by Argon Ion Induced Chemical Sputtering

Cyriac

Pradeep

2008

J. Phys. Chem. C

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“…Avariety of processes occurring during interaction of both small and large ions with different surfaces have been extensively reviewed (Cooks, Ast, & Mabud, 1990;Dongre, Somogyi, & Wysocki, 1996;Grill et al, 2001;Jacobs, 2002). Physical and chemical properties of the surface play an important role in determining the outcome of the collision.…”

Section: Introductionmentioning

confidence: 99%

“…An alternative approach introduced by Cooks and coworkers (Mabud, Dekrey, & Cooks, 1985;Cooks, Ast, & Mabud, 1990) relies on very fast, single-step excitation of the ion in collision with a surface, resulting in surface-induced dissociation (SID). Avariety of processes occurring during interaction of both small and large ions with different surfaces have been extensively reviewed (Cooks, Ast, & Mabud, 1990;Dongre, Somogyi, & Wysocki, 1996;Grill et al, 2001;Jacobs, 2002).…”

Section: Introductionmentioning

confidence: 99%

Activation of large lons in FT‐ICR mass spectrometry

Laskin

Futrell

2004

Mass Spectrometry Reviews

177

146

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The advent of soft ionization techniques, notably electrospray and laser desorption ionization methods, has enabled the extension of mass spectrometric methods to large molecules and molecular complexes. This both greatly extends the applications of mass spectrometry and makes the activation and dissociation of complex ions an integral part of these applications. This review emphasizes the most promising methods for activation and dissociation of complex ions and presents this discussion in the context of general knowledge of reaction kinetics and dynamics largely established for small ions. We then introduce the characteristic differences associated with the higher number of internal degrees of freedom and high density of states associated with molecular complexity. This is reflected primarily in the kinetics of unimolecular dissociation of complex ions, particularly their slow decay and the higher energy content required to induce decomposition-the kinetic shift (KS). The longer trapping time of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) significantly reduces the KS, which presents several advantages over other methods for the investigation of dissociation of complex molecules. After discussing general principles of reaction dynamics related to collisional activation of ions, we describe conventional ways to achieve single-and multiple-collision activation in FT-ICR MS. Sustained off-resonance irradiation (SORI)-the simplest and most robust means of introducing the multiple collision activation process-is discussed in greatest detail. Details of implementation of this technique, required control of experimental parameters, limitations, and examples of very successful application of SORI-CID are described. The advantages of high mass resolving power and the ability to carry out several stages of mass selection and activation intrinsic to FT-ICR MS are demonstrated in several examples. Photodissociation of ions from small molecules can be effected using IR or UV/vis lasers and generally requires tuning lasers to specific wavelengths and/ or utilizing high flux, multiphoton excitation to match energy levels in the ion. Photodissociation of complex ions is much easier to accomplish from the basic physics perspective. The quasi-continuum of vibrational states at room temperature makes it very easy to pump relatively large amounts of energy into complex ions and infrared multiphoton dissociation (IRMPD) is a powerful technique for characterizing large ions, particularly biologically relevant molecules. Since both SORI-CID and IRMPD are slow activation methods they have many common characteristics. They are also distinctly different because SORI-CID is intrinsically selective (only ions that have a cyclotron frequency close to the frequency of the excitation field are excited), whereas IRMPD is not (all ions that reside on the optical path of the laser are excited). There are advantages and disadvantages to each technique and in many applications they complement each other. In contrast wi...

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“…[1][2][3][4] The diversity of the chemistry, 4 its implications for materials design, 5 and the technological applications of surface transformations 6 are all important. Investigation of ion/surface collisions [7][8][9][10] and increased understanding of the molecular details of the processes by performing analogous ion/molecule collisions 8,11 have widened the scope of this area.…”

Section: Introductionmentioning

confidence: 99%

Adsorbate Geometry Distinction in Arenethiols by Ion/Surface Reactive Collisions

et al. 1999

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Reactive scattering of low-energy ions from surfaces gives scattered product ions in which new bonds are formed with the adsorbate with a sensitivity to adsorbate geometry. Reactions of Cr •+ and C 5 H 5 N •+ , as well as chemical sputtering induced by Xe •+ , are used to distinguished two well-characterized monolayer systems, namely 1,4-benzenedimethanethiol (BDMT) adsorbed on Au(111) and Ag(111) thin films. While the reaction of Cr •+ with the Au monolayer produces an ion assigned as CrC 7 H 5 S + , this product is completely absent upon reaction with the Ag monolayer. Pyridine (C 5 H 5 N •+ ) projectiles abstract C 1 -C 8 hydrocarbon groups in 50 eV collisions with the Au monolayer, while the Ag monolayer shows only C 1 -C 4 abstraction with a significantly different intensity pattern. Chemical sputtering (Xe •+ ) mass spectra of the two surfaces are substantially different; complete fragmentation of the Ag adsorbate occurs, leading to C 2 -C 4 ion ejection, while more of the molecular features are preserved in the spectrum recorded for the Au monolayer. The experimental facts are interpreted in terms of the geometry of the BDMT molecule that is monocoordinated on Au and dicoordinated on Ag. The experiments are extended to the 1,2-and 1,3-ring isomers of 1,4-BDMT, which have not been characterized by other forms of surface spectroscopy. Ion/surface reactive collisions are useful for characterizing chemisorbates, including their geometrical orientation.

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Collisions of polyatomic ions with surfaces

Cited by 305 publications

References 83 publications

Interaction of Carboxylic Acids and Water Ice Probed by Argon Ion Induced Chemical Sputtering

Interaction of Carboxylic Acids and Water Ice Probed by Argon Ion Induced Chemical Sputtering

Activation of large lons in FT‐ICR mass spectrometry

Adsorbate Geometry Distinction in Arenethiols by Ion/Surface Reactive Collisions

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