Mechanisms in molecular SIMS

Pachuta, Steven J.; Cooks, R. Graham

doi:10.1021/cr00079a009

Cited by 202 publications

(86 citation statements)

References 68 publications

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“…Here, as with the samples prepared from solution, we see the dramatic The fact that the results from these two different sample preparation techniques are very similar, in terms of the ions present, suggests that the factors determining the ions that are detected occur after the impact of the primary ion. In addition, it has been shown that there must be a large degree of mixing within the perturbed region of the sample, which is in agreement withöpreviousöworköonösimilarösampleötypesö [40].…”

Section: Ggh and Thap As Pressed Powder Samplesupporting

confidence: 77%

Suppression and enhancement of secondary ion formation due to the chemical environment in static-secondary ion mass spectrometry

Jones

Lockyer

Kordys

et al. 2007

J. Am. Soc. Mass Spectrom.

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Through analyzing mixtures of compounds of known gas-phase basicities, the importance of this property on the secondary ions emitted from a surface under primary ion bombardment is investigated. The aim is to obtain a greater understanding of the ionization mechanisms that occur in secondary ion mass spectrometry (SIMS). The commonly used matrix assisted laser desorption/ionization (MALDI) matrix 2,4,6-trihydroxyacetophenone (THAP) and a range of low molecular weight biomolecules were used to investigate whether analyte/matrix suppression effects that have been observed in analogous MALDI experiments were also present in static-SIMS. The outcome of the experiments demonstrates that strong suppression of the quasi-molecular signal of one molecule in a mixture can occur due to the presence of the other, with the gas-phase basicity of the compounds being a good indicator of the secondary ions detected. It is also demonstrated that the suppression of the quasi-molecular ion signal of a compound in a two-component mixture can be minimized by the inclusion of a third compound of suitable gas-phase basicity. (J Am Soc Mass Spectrom 2007, 18, 1559 -1567

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Section: Ggh and Thap As Pressed Powder Samplesupporting

confidence: 77%

Suppression and enhancement of secondary ion formation due to the chemical environment in static-secondary ion mass spectrometry

Jones

Lockyer

Kordys

et al. 2007

J. Am. Soc. Mass Spectrom.

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“…The family of desorption ionization (DI) techniques, including liquid secondary ion mass spectrometry (L-SIMS) [20], fast atom bombardment (FAB) [21][22][23][24][25], and matrix-assisted laser desorption ionization (MALDI), provide one type of approach to the examination of the post soft-landed materials. In early reports, Hillenkamp et al [26] and Tanaka and coworkers [27] used liquid matrices as means to detect various analytes by mass spectrometry.…”

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confidence: 99%

Ion soft-landing into liquids: Protein identification, separation, and purification with retention of biological activity

Gologan

Takáts

Alvarez

et al. 2004

J. Am. Soc. Mass Spectrom.

122

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Protein ions, after mass spectrometric separation, can be soft-landed into liquid surfaces with preservation of their native structures. Retention of biological activity is strongly favored in glycerol-based surfaces but not in self-assembled monolayer solid surfaces. Soft-landing efficiency for multiply-charged hexokinase ions was found to be some four times higher for a glycerol/fructose liquid surface than for a fluorinated self-assembled monolayer surface. Soft-landing into liquid surfaces is also shown to allow (1) protein purification, (2) on-surface identification of the soft-landed material using MALDI, and (3) protein identification by in-surface tryptic digestion. Pure lysozyme was successfully isolated from different mixtures including an oxidized, partially decomposed batch of the protein and a partial tryptic digest. Liquid glycerol/carbohydrate mixtures could be used directly to record MALDI spectra on the soft-landed compounds provided they were fortified in advance with traditional MALDI matrices such as p-nitroaniline and ␣-cyano-4-hydroxycinnamic acid. Various proteins were soft-landed and detected on-target using these types of liquid surface. Soft-landing of multiply-charged lysozyme ions onto fluorinated self-assembled monolayer surfaces was found to occur with a limited amount of neutralization, and trapped multiply-charged ions could be desorbed from the surface by laser desorption. Initial data is shown for a new approach to protein identification that combines top-down and bottom-up approaches by utilizing protein ion soft-landing from a protein mixture, followed by tryptic digestion of the landed material and detection of characteristic tryptic fragments by MALDI. , has been applied in experiments ranging from studies using chemically inert and structurally organized self-assembled monolayers (SAMs) as substrates for ion storage [2], to studies of ion mobility through ice and vapor deposited films [3,4], to experiments aimed at developing a separation method in a form of preparatory mass spectrometry [5,6]. Simple organic cations [7,8] [12][13][14] have all been the targets of examination by ion soft-landing. The separation, purification, and storage of chemical species by a completely non-destructive, mass spectrometric approach are the objectives of the studies currently underway in our laboratory.In a preliminary report [5], we described a method which showed the potential for generating biologically active protein chips from protein mixtures by massselective ion soft-landing. After ionization of the mixture by electrospray (ESI), individual protein ions were mass-selected and soft-landed at predetermined locations on the surface. The results showed that the use of mass spectrometry as a separation method in biology provides high selectivity because components with different molecular formulas can be separated and softlanded. However, retention of the biological activity of a protein or other biomolecule in the course of this (or any mass spectrometry experiment) is a much more chall...

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“…In mass spectrometry, several investigators [34][35][36] already described the model of desorption-ionization (DI) processes for organic molecules, and the detailed example and discussion was indicated by Lenaerts and co-workers [37]. Fast thermal processes are assumed to be responsible for generating primarily neutrals in the selvedge.…”

Section: Resultsmentioning

confidence: 99%

Theoretical Mass Spectra of PE, PP, PS and PET Polymers by QMD Methods Using the Model Molecules

Endo

Hayashi

Ida

et al. 2010

JSA

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We used a quantum molecular dynamics {QMD (MD with MO)} due to the force function of MO with the velocity Verlet algorithm using the model oligomers of PE, PP, PS, and PET polymers to obtain theoretical mass spectra of the polymers. The QMD calculation was performed in the thermal energy range of 0.69 ∼ 0.95 eV, and the sampling position data by a time step of 0.5 fs were performed up to 5000 steps. The fragments at the final step of 60 trajectories in the QMD were obtained as positive, negative, and neutral charged ones from the net atomic charge analysis at geometry-optimization of the MO SCF calculations. We can compare the positive ion fragments of polymer models with the experimental distribution of polymers in mass spectra and secondary ionization mass spectra after a few tens of keV of primary heavy metal ion bombardment. We also showed the chemical structures of fragments for PE, PP, PS, and PET polymers in positive ion spectra, unavailable from experimental methods.

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Mechanisms in molecular SIMS

Cited by 202 publications

References 68 publications

Suppression and enhancement of secondary ion formation due to the chemical environment in static-secondary ion mass spectrometry

Suppression and enhancement of secondary ion formation due to the chemical environment in static-secondary ion mass spectrometry

Ion soft-landing into liquids: Protein identification, separation, and purification with retention of biological activity

Theoretical Mass Spectra of PE, PP, PS and PET Polymers by QMD Methods Using the Model Molecules

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