The curved-field reflectron: PSD and CID without scanning, stepping or lifting

Cotter, Robert J.; Iltchenko, Serguei; Wang, Dongxia

doi:10.1016/j.ijms.2004.09.022

Cited by 10 publications

(9 citation statements)

References 31 publications

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“…The collision gas pressure in the chamber cannot be measured directly, so that the vacuum chamber pressure (Torr) was monitored to insure reproducible conditions. The experiments reported here were carried out at pressures which we have shown earlier from pressure dependence measurements on this instrument to correspond to primarily single-collision conditions [25]. The normal acceleration energy for ions in this instrument is 20 keV.…”

Section: Methodsmentioning

confidence: 99%

“…visible [25,36]. An MS/MS spectrum of fullerene with helium, at high attenuation and at 20 keV, is shown in Fig.…”

Section: Collision-induced Dissociation Versus Post-source Decaymentioning

confidence: 99%

“…In this investigation we detect heliumtrapped fragments using a unique time-of-flight mass analyzer with a curved field reflectron. In this case, it is not necessary to decelerate the ions to very low kinetic energies prior to collision in order to accommodate the focusing bandwidth of the reflectron [25]; therefore, it is possible to investigate a wide range of collision energies by simply reducing the initial acceleration voltage. Within each single spectrum we detected metastable, CID and (for lower collision energies) trapped helium fragments, from which we determined the time (apparent mass) shifts that enabled us to assess the different types of collisions based on impulse collision theory (ICT) [9].…”

Section: Introductionmentioning

confidence: 99%

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Collision energetics in a tandem time-of-flight (TOF/TOF) mass spectrometer with a curved-field reflectron

Ilchenko

Cotter

2007

International Journal of Mass Spectrometry

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Collisions of fullerene ions (C(60) (+)) with helium and neon were carried out over a range of laboratory energies (3-20 keV) on a unique tandem time-of-flight (TOF/TOF) mass spectrometer equipped with a curved-field reflectron (CFR). The CFR enables focusing of product ions over a wide kinetic energy range. Thus, ions extracted from a laser desorption/ionization (LDI) source are not decelerated prior to collision, and collision energies in the laboratory frame are determined by the source extraction voltages. Comparison of product ion mass spectra obtained following collisions with inert gases show a time (and apparent mass) shift for product ions relative to those observed in spectra obtained by metastable dissociation (unimolecular decay), consistent with impulse collision models, in which interactions of helium with fullerene in the high energy range are primarily with a single carbon atom. In addition, within a narrow range of kinetic energies an additional peak corresponding to the capture of helium is observed for fragment ions C(50) (+), C(52) (+), C(54) (+), C(56) (+) and C(58) (+).

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Section: Methodsmentioning

confidence: 99%

“…visible [25,36]. An MS/MS spectrum of fullerene with helium, at high attenuation and at 20 keV, is shown in Fig.…”

Section: Collision-induced Dissociation Versus Post-source Decaymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Collision energetics in a tandem time-of-flight (TOF/TOF) mass spectrometer with a curved-field reflectron

Ilchenko

Cotter

2007

International Journal of Mass Spectrometry

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“…Hydrogen radical donating abilities of various matrixes have been measured [30] and results show that DHB or DAN matrixes are capable of providing H • much more readily than CHCA. Conversely, PSD is a much slower dissociation process induced by vibrational energy uptake of the analytes, similar to the energy uptake occurring in collision induced decomposition (CID) processes [38].…”

Section: Maldi In-source Decay (Isd) Of Pomc12 Mechanism Of Decomposmentioning

confidence: 99%

Negative Ion MALDI Mass Spectrometry of Polyoxometalates (POMs): Mechanism of Singly Charged Anion Formation and Chemical Properties Evaluation

Boulicault

Alvès

Cole

2016

J. Am. Soc. Mass Spectrom.

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Abstract. MALDI-MS has been developed for the negative ion mode analysis of polyoxometalates (POMs). Matrix optimization was performed using a variety of matrix compounds. A first group of matrixes offers MALDI mass spectra containing abundant intact singly charged anionic adduct ions, as well as abundant in-source fragmentations at elevated laser powers. A relative ranking of the ability to induce POM fragmentation is found to be: DAN > CHCA > CNA > DIT> HABA > DCTB > IAA. Matrixes of a second group provide poorer quality MALDI mass spectra without observable fragments. Sample preparation, including the testing of salt additives, was performed to optimize signals for a model POM, POMc12, the core structure of which bears four negative charges. The matrix 9-cyanoanthracene (CNA) provided the best signals corresponding to singly charged intact POMc12 anions. Decompositions of these intact anionic species were examined in detail, and it was concluded that hydrogen radical-induced mechanisms were not prevalent, but rather that the observed prompt fragments originate from transferred energy derived from initial electronic excitation of the CNA matrix. Moreover, in obtained MALDI mass spectra, clear evidence of electron transfer to analyte POM species was found: a manifestation of the POMs ability to readily capture electrons. The affinity of polyanionic POMc12 toward a variety of cations was evaluated and the following affinity ranking was established: Fe 3+ > Al 3+ > Li + > Ga 3+ > Co 2+ > Cr 3+ > Cu 2+ > [Mn 2+ , Mg 2+ ] > [Na + , K + ]. Thus, from the available cationic species, specific adducts are preferentially formed, and evidence is given that these higher affinity POM complexes are formed in the gas phase during the early stages of plume expansion.

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“…The term 'curved field' ion mirror introduced by Cotter 19 has a strong footprint in the literature [20][21][22][23][24][25][26][27][28][29] and is presumed to carry meaning beyond the self-evident. There are a number of questions, including whether the curved-field mirror refers to a definite potential distribution within an ion mirror and the extent to which the term has meaning beyond simply an ion mirror not falling into one of the three basic categories of one-stage, two-stage and ideal.…”

Section: Introductionmentioning

confidence: 99%

Unveiling the Intricacies of the Curved-Field Ion Mirror

Maechler

Fillipov

Derrick

2015

Eur J Mass Spectrom (Chichester)

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In time-of-flight (ToF) mass spectrometry, non-linear ion mirrors, i.e. mirrors that produce a non-linear potential in which the ions fly, can focus ions exhibiting a very broad kinetic energy distribution. Besides the quadratic potential, the so-called curved field has been used in mirrors as a non-linear potential over the past 20 years. The curved field has, however, only been loosely defined. The focusing properties of the curved field appear to have never been mathematically investigated and explained. In this work, we put forward a rigid definition of the curved field and investigate the properties of it in terms of focusing and transmission. This rigid definition shows the curved field as a two-parameter function for a given mirror length and maximum potential, which can be optimized in terms of ToF distribution/resolution. Such an optimization was performed in one- dimension (1D) by solving the ToF integral equation numerically. The characteristics of optimized configurations arrived at through a comparison with mirrors with polynomial distance-potential relationships are assessed. These optimised solutions cannot be approximated in 1D by a common set of polynomial terms. There are optimised configurations affording ideal energy focussing, but on closer inspection, these potential distributions are found to be, in fact, quadratic potentials. There are other optimised solutions that afford good energy focussing in cases of there being significant field-free regions between the source/detector and the entrance to the mirror. Some of these configurations are approximated by a linear plus a quadratic term, others need higher-order terms to be approximated. To facilitate 3D investigation, the optimised solutions in 1D were used to set the initial voltages on electrodes in a rotationally symmetric mirror, which was modelled with the computer package SIMION 8.0. The SIMION ion-flight simulations revealed that the other optimised solutions with higher-order terms have the disadvantage of lowering the transmittance. That is to say, in 3D the configurations of the curved field, which give good resolution and transmittance with field- free regions between source/detector and mirror, can all be approximated by a potential consisting of a linear plus a quadratic term.

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The curved-field reflectron: PSD and CID without scanning, stepping or lifting

Cited by 10 publications

References 31 publications

Collision energetics in a tandem time-of-flight (TOF/TOF) mass spectrometer with a curved-field reflectron

Collision energetics in a tandem time-of-flight (TOF/TOF) mass spectrometer with a curved-field reflectron

Negative Ion MALDI Mass Spectrometry of Polyoxometalates (POMs): Mechanism of Singly Charged Anion Formation and Chemical Properties Evaluation

Unveiling the Intricacies of the Curved-Field Ion Mirror

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