Surface secondary electron and secondary ion emission induced by large molecular ion impacts

Brunelle, Alain; Chaurand, Pierre; Della‐Negra, S.; Beyec, Y. Le; Baptista, G.B.

doi:10.1016/0168-1176(93)80071-l

Cited by 45 publications

(34 citation statements)

References 16 publications

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“…In contrast, Tabet and coworkers observed the opposite trend for BSA: lowering the analyte concentration led to a decrease of doubly charged ions in their experiments using a conventional microchannel plate (MCP) detector [22]. The MCP suffers from very low sensitivity for high-mass ions due to their low velocity and saturation effects caused by long channel recovery times [46][47][48]. With increasing sample concentration, more channels are blocked and the saturation effect of an MCP becomes more prominent.…”

Section: Influence Of Experimental Parameters On the Charge Distributionmentioning

confidence: 85%

Compelling Advantages of Negative Ion Mode Detection in High-Mass MALDI-MS for Homomeric Protein Complexes

Mädler

Barylyuk

Erba

et al. 2011

J. Am. Soc. Mass Spectrom.

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Chemical cross-linking in combination with high-mass MALDI mass spectrometry allows for the rapid identification of interactions and determination of the complex stoichiometry of noncovalent protein-protein interactions. As the molecular weight of these complexes increases, the fraction of multiply charged species typically increases. In the case of homomeric complexes, signals from multiply charged multimers overlap with singly charged subunits. Remarkably, spectra recorded in negative ion mode show lower abundances of multiply charged species, lower background, higher reproducibility, and, thus, overall cleaner spectra compared with positive ion mode spectra. In this work, a dedicated high-mass detector was applied for measuring highmass proteins (up to 200 kDa) by negative ion mode MALDI-MS. The influences of sample preparation and instrumental parameters were carefully investigated. Relative signal integrals of multiply charged anions were relatively independent of any of the examined parameters and could thus be approximated easily for the spectra of cross-linked complexes. For example, the fraction of doubly charged anions signals overlapping with the signals of singly charged subunits could be more precisely estimated than in positive ion mode. Sinapinic acid was found to be an excellent matrix for the analysis of proteins and cross-linked protein complexes in both ion modes. Our results suggest that negative ion mode data of chemically cross-linked protein complexes are complementary to positive ion mode data and can in some cases represent the solution phase situation better than positive ion mode.

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Section: Influence Of Experimental Parameters On the Charge Distributionmentioning

confidence: 85%

Compelling Advantages of Negative Ion Mode Detection in High-Mass MALDI-MS for Homomeric Protein Complexes

Mädler

Barylyuk

Erba

et al. 2011

J. Am. Soc. Mass Spectrom.

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“…The experimental set-up and the acquisition system are similar to those described in Ref. 22. The molecules used as projectiles are given in Table 1.…”

Section: Experimental Set-upmentioning

confidence: 99%

“…1. 22 The reflected molecular ion beam first goes through the 10 mm diameter hole of the annular microchannel plates detector 1 (MCP 1 , which has a diameter of 44 mm) and then hits, 20 cm further on, the conversion surface covered with a 200 nm CsI deposit. The total flight distance is 2.2 m. A post-accelerating potential is applied between a grounded extractor and the conversion surface biased at a potential between -0.7 and -8 kV.…”

Section: Experimental Set-upmentioning

confidence: 99%

“…The extractor used in front of the conversion surface is a simple metallic plate with a 15 mm diameter hole having its centre on the optical axis in order to avoid grid effects observed with heavy molecular ions. 22 The vacuum pressure in the spectrometer was 5 × 10 -7 (1 hPa ϵ 0.76 Torr).…”

Section: Experimental Set-upmentioning

confidence: 99%

“…We use the system described in Ref. 22, which is composed of the time-todigital converter (TDC) and the charge to digital converter (CDC). 47 The time-of-flight spectra of primary ions are obtained by using the laser pulse to trigger the time measurement; the time-of-flight stop signals are obtained by the secondary electron detection on the MCP 2 detector (Fig.…”

Section: Data Acquisition Modementioning

confidence: 99%

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Secondary Electron Emission Yields from a CsI Surface Under Impacts of Large Molecules at Low Velocities (5 × 103−7 × 104 ms−1)

Brunelle

Chaurand

Della‐Negra

et al. 1997

Rapid Commun. Mass Spectrom.

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The yields of electron emission from a CsI surface bombarded with very heavy molecular ions have been measured by coincidence counting in time-of-flight mass spectrometry. These ions were produced by the matrix-assisted laser desorption/ionization technique. The masses ranged from 700 to 66 000 Da with velocities V between 5 × 10 3 and 7 × 10 4 ms For a few years, the interaction of heavy clusters and molecules with solids has been the subject of welldeveloped research. In these investigations the projectiles have had energies from a few eV/atom to a few MeV/atom. Over this large domain of velocities, the projectiles deposit a large amount of energy near the surface of the target. For masses in the range of 10 000 u to 100 000 u, energies of 10 keV to 2 MeV are deposited in a small volume. The transfer of very high densities of transitory and out-of-equilibrium energy into the solid leads to important modifications of the material and/or to the formation of craters independent of the energy range, the mass of the projectiles and the nature of the bombarded surface.1-5 Crater formation is accompanied by a very high sputter yield, as was first observed by Andersen and Bay. 6 The other de-excitation channels, such as electron and ion emission, have also been studied. The ion emission yield exhibits a non-linear increase as a function of the number of constituents or the mass of the projectile over the velocity range studied.7-10 For electron emission, results are scarce. Fundamentally, the electron emission induced by ions is connected to the ion/electron interaction in the medium. The electron emission processes are not simple, and the experimental results show both linear and non-linear relationships of the electron emission yield as a function of the velocity of the projectiles. 11-13

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A comparison between ion-to-photon and microchannel plate detectors

Dubois

Knochenmuss

Zenobi

et al. 1999

Rapid Commun. Mass Spectrom.

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An alternative detector for time-of-flight mass spectrometry, the ion-to-photon detector, detecting light produced when ions impact a surface coated with a fluorescent compound, was compared to a conventional microchannel plate detector. Single ion experiments showed that, for a given energy, the efficiency of the ion-to-photon detector relative to the microchannel plate detector decreases as the molecular mass of the impinging ion increases. This decrease becomes less pronounced for larger ions. Seen as a function of the ion velocity, a linear relationship was found. The conversions into photons and electrons were also compared. It was found that 22 keV ions up to 150 Da produced more photons than secondary electrons. For larger ions at this energy, the opposite was observed.

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Surface secondary electron and secondary ion emission induced by large molecular ion impacts

Cited by 45 publications

References 16 publications

Compelling Advantages of Negative Ion Mode Detection in High-Mass MALDI-MS for Homomeric Protein Complexes

Compelling Advantages of Negative Ion Mode Detection in High-Mass MALDI-MS for Homomeric Protein Complexes

Secondary Electron Emission Yields from a CsI Surface Under Impacts of Large Molecules at Low Velocities (5 × 103−7 × 104 ms−1)

A comparison between ion-to-photon and microchannel plate detectors

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