Secondary electron emission induced by impact of low-velocity molecular ions on a microchannel plate

Geno, Paul W.; Macfarlane, Ronald D.

doi:10.1016/0168-1176(89)83028-9

Cited by 100 publications

(78 citation statements)

References 14 publications

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“…The last type of correction involves the m/z bias of the microchannel plate (MCP) detector. The efficiency with which an ion generates a secondary electron in the MCP has been shown to vary as follows [32][33][34]:…”

Section: Mass Spectrometry and Data Analysismentioning

confidence: 99%

Controlling gas-phase reactions for efficient charge reduction electrospray mass spectrometry of intact proteins

Frey

Lin

Westphall

et al. 2005

J. Am. Soc. Mass Spectrom.

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Charge reduction electrospray mass spectrometry (CREMS) reduces the charge states of electrospray-generated ions, which concentrates the ions from a protein into fewer peaks spread over a larger m/z range, thereby increasing peak separation and decreasing spectral congestion. An optimized design for a CREMS source is described that provides an order-ofmagnitude increase in sensitivity compared to previous designs and provides control over the extent of charge reduction. Either a corona discharge or an ␣-particle source was employed to generate anions that abstract protons from electrosprayed protein cations. These desired ion/ion proton transfer reactions predominated, but some oxidation and ion-attachment reactions also occurred, leading to new peaks or mass-shifted broader peaks while decreasing signal intensity. The species producing these deleterious side-reactions were identified, and conditions were found that prevented their formation. Spectrometer m/z biases were examined because of their effect upon the signal intensity of higher m/z charge-reduced protein ions. The utility of this atmospheric pressure CREMS was demonstrated using a cell lysate fraction from E. coli. The spectral simplification afforded by CREMS reveals more proteins than are observed without charge reduction. (J Am Soc Mass Spectrom 2005, 16, 1876 -1887

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Section: Mass Spectrometry and Data Analysismentioning

confidence: 99%

Controlling gas-phase reactions for efficient charge reduction electrospray mass spectrometry of intact proteins

Frey

Lin

Westphall

et al. 2005

J. Am. Soc. Mass Spectrom.

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“…2. The drift length to the junction, operated in a 4 He cryostat at 1.4 K, was 173 cm, and to the MCP, mounted off-axis, was 122 cm. The sample was human serum albumin (HSA, mass 66 000 u) with a sinapinic acid matrix.…”

Section: Recent Demonstrations Of Superconducting Detectors Coupled Tmentioning

confidence: 99%

“…Cryostats, both 4 He (operating temperature down to 1.2 K) and 3 He (down to 0.3 K), with side access are available commercially from a number of firms. The most suitable type is similar to the 3 He system initially designed for infrared studies.…”

Section: Practicalitiesmentioning

confidence: 99%

“…This principle eventually breaks down as m/z increases, because the incoming ions have insufficient velocity to impart enough energy to an electron in the material of the detector to initiate secondary electron emission. Detailed measurements 4 indicate an exponential falloff in the SEM probability as the velocity decreases, such that, for example for bovine insulin (m = 5734 u), the detection efficiency is about 14% for a velocity of 2 × 10 4 m s . Alternative detectors based on charge detection, either directly 5,6 or inductively, 7 have been developed for TOF spectrometers, and these have efficiencies which are independent of mass.…”

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confidence: 99%

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Erratum: Calorimetric Detectors for High Mass Ions. Norman E. Booth.Rapid Communications in Mass Spectrometry, volume 11, no.2 (1997)

Booth

1997

Rapid Commun. Mass Spectrom.

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In mass spectrometry, the ions of interest are usually detected by techniques based on secondary electron emission using electron multipliers or micro-channel plates. For large ions of biological interest, these detection techniques are inefficient and eventually break down as the ion mass increases. We discuss the use of low-temperature detectors which have an efficient response which extends to the highest masses. Recent tests show that a low-temperature calorimetric detector can measure the kinetic energy of individual incident ions irrespective of their mass or charge state. This detection scheme, when used in a time-of-flight spectrometer, could yield both the mass and the charge state of individual ions.

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“…Further, by distributing ion flux across a number of discrete detectors, pulse pile-up issues often troublesome in TOFMS are alleviated. In addition, the possible incorporation of discrete charge-detector arrays [8,9] offers substantial dynamic range improvements over state-of-the-art TOFMS detector technology, while also reducing mass bias inherent to current TOFMS detection [10,11]. In both DOFMS and TOFMS ions arrive at the detectors intermittently as ion bunches are accelerated out of the source region.…”

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confidence: 99%

First Distance-of-Flight Instrument: Opening a New Paradigm in Mass Spectrometry

Graham

Ray

Enke

et al. 2011

J. Am. Soc. Mass Spectrom.

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A new instrumental concept, distance-of-flight mass spectrometry (DOFMS), is demonstrated experimentally. In DOFMS the mass-to-charge ratio of ions is determined by the distance each ion travels during a fixed time period; the mass spectrum is then recorded with a positionsensitive detector. The DOF approach provides a new way to separate and quantify components of complex samples. Initial results are demonstrated with a glow discharge ion source and a microchannel plate-phosphor screen detector assembly for atomic ion determination. This detection system demonstrated mass spectral peak widths of approximately 0.65 mm, corresponding to resolving powers of approximately 400-600 for a number of elemental samples.Key words: Mass spectrometry, Instrumentation, Glow discharge S ince the development of the first mass spectrograph over 90 years ago [1], numerous methods and instruments have been developed to separate and determine ions of varying mass-to-charge ratio (m/z). Currently, mass spectrometry (MS) can be accomplished by electrostatic and magnetic dispersion (sector-field MS), radio-frequency stability and filtering (quadrupoles and ion traps), resonance frequency determination (Fourier-transform ion cyclotron resonance and Orbitrap® MS), or velocity-based separation (time-of-flight MS). These mature MS technologies are routinely employed in a range of applications from biomolecule analysis to elemental isotope determination, and are often coupled with each other to achieve tandem MS analysis [2,3]. In the present paper, we describe the first implementation of a new form of MS, termed distance-offlight mass spectrometry (DOFMS), and suggest potential benefits of this new mass separation technique.Distance-of-flight mass spectrometry is akin to time-offlight mass spectrometry (TOFMS) in that both techniques separate ions of different m/z based upon an imparted m/zdependent velocity. In TOFMS, each ion is given the same energy (thus achieving a m/z-dependent velocity), and the m/z of each ion is calculated from the time required for it to traverse a known distance to a single detector. Conversely, in DOFMS the m/z of an ion is measured based on the spatial location of each ion at a specific time after the initial acceleration. As a useful analogy, DOFMS is to TOFMS as thin-layer chromatography is to elution chromatography (e.g., LC). TOFMS measures ions as they come off the "column", whereas DOFMS measures how far the ions travel after a specific separation time. Whereas TOFMS disperses ions in time, DOFMS disperses ions in space.The principle behind DOFMS is illustrated in Figure 1. To implement DOFMS, the primary ion beam is introduced into an orthogonal extraction region where ions are subjected to a brief electrostatic field, imparting identical momentum to each ion. This constant-momentum acceleration (CMA) is accomplished by limiting the temporal width and electrostatic field

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Secondary electron emission induced by impact of low-velocity molecular ions on a microchannel plate

Cited by 100 publications

References 14 publications

Controlling gas-phase reactions for efficient charge reduction electrospray mass spectrometry of intact proteins

Controlling gas-phase reactions for efficient charge reduction electrospray mass spectrometry of intact proteins

Erratum: Calorimetric Detectors for High Mass Ions. Norman E. Booth.Rapid Communications in Mass Spectrometry, volume 11, no.2 (1997)

First Distance-of-Flight Instrument: Opening a New Paradigm in Mass Spectrometry

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