Ionization in liquid secondary ion mass spectrometry (LSIMS)

Sunner, Jan

doi:10.1002/oms.1210280802

Cited by 72 publications

(36 citation statements)

References 137 publications

(21 reference statements)

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“…This agrees well with the observation that the relative abundance of water-containing clusters with the same n:m is higher in the negative-ion mode in comparison with that in the positive-ion mode. An alternative possible mechanism of formation of negative ions by the attachment of the electrons formed under ion/atom bombardment 17 does not explain the selectivity in relation to water-enriched clusters.…”

Section: Discussionmentioning

confidence: 88%

Comparison of Positive and Negative Ion Clusters of Methanol and Ethanol Observed by Low Temperature Secondary Ion Mass Spectrometry

Kosevich

Czira

Boryak

et al. 1997

Rapid Commun. Mass Spectrom.

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Positively and negatively charged cluster ions were produced from methanol and ethanol samples under low temperature secondary ion mass spectrometric conditions. Neat alcohol clusters [ The comparatively large number of reports of studies of alcohol clusters by various mass spectrometric techniques 1-13 establishes them as one of the favourite subjects of study of hydrogen bonded clusters of organic molecules. Low temperature (LT) fast-atom bombardment (FAB) or secondary ion mass spectrometric (SIMS) techniques allow cluster production from the condensed state. The LT FAB mass spectra of alcohols have already been reported in a number of pioneering studies in the case of methanol 1,2 and ethanol.3 The main objects of interest in these studies were the protonated neat alcohol clusters M n .H + ] (always formed due to practically unavoidable water traces in the alcohol), with m = 1 for ethanol and m ≤ 3 for methanol, were recorded in these works but not discussed in detail. To our knowledge, all data reported previously were related to positive ions.In the present work the LT SIMS mass spectra of methanol and ethanol, recorded with much higher sensitivity, resolution and mass range than before, are reported. Negatively charged alcohol cluster ions are studied for the first time and their formation is discussed. EXPERIMENTALMeasurements in the LT SIMS mode were performed using a ZAB-SEQ instrument (Micromass, Manchester, UK). The energy of the bombarding Cs + ions was 15 keV.A droplet of an alcohol with 5 µL volume was deposited on the stainless steel probe tip and frozen in a small vessel filled with liquid nitrogen. The vessel was moved then to the immediate vicinity of the entrance of the direct inlet system in such a way that the probe tip was kept in the dry vapours of nitrogen during its quick transfer to the vacuum lock. Pumping to high vacuum before starting the measurements took no longer than about one minute. The spectra were recorded at a rate of 5 s per scan.The thawing of the sample allowed us to monitor changes in the spectra with increasing temperature. Under the conditions applied, the alcohol samples 'survived' in the ion source for 5-10 min.Sample temperature was not measured directly in the present experiments. The temperature range in which abundant alcohol clusters are observed in the spectra can be derived from our previous work (using an LT FAB ion source, described elsewhere) 4,14 and suggests a range of -140 °C to -100 °C for methanol and -130 °C to -110 °C for ethanol. Analytical grade ethanol and methanol samples ('Reanal', Hungary) were used without additional purification. RESULTS AND DISCUSSION General features of the LT SIMS mass spectra of alcoholsThe general features of changes in the LT SIMS mass spectra of ethanol and methanol as a function of temperature were the same as those described in the previous publications on LT FAB of alcohols. [1][2][3][4][5][6] In the lowest temperature range (starting from liquid nitrogen temperature) the LT SIMS spectrum has a noisy, featureless cha...

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Section: Discussionmentioning

confidence: 88%

Comparison of Positive and Negative Ion Clusters of Methanol and Ethanol Observed by Low Temperature Secondary Ion Mass Spectrometry

Kosevich

Czira

Boryak

et al. 1997

Rapid Commun. Mass Spectrom.

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“…28,29 The higher stability of secondary electrons in glycerol, when compared with 3-NBA, can favor either recombination reactions with glycerol ions or dissociative electron capture by glycerol atoms, over electron capture by the pentafluorobenzyl substituents of the analyte. 28 Other ions in the mass spectrum of compound IIB can be rationalized as being formed from both the …”

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confidence: 99%

Cycloreversion and other gas‐phase reactions of neutral and cationic pyrrolidine‐fused chlorins and isobacteriochlorins under ion bombardment and electrospray

Izquierdo

Barros

Santana-Marques

et al. 2004

Rapid Comm Mass Spectrometry

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Neutral and cationic pyrrolidine-fused chlorins and isobacteriochlorins derived from meso-tetrakis(pentafluorophenyl)porphyrin undergo cycloreversion reactions in the gas phase, either when desorbed from a liquid matrix by ion bombardment or when electrosprayed. Cycloreversion occurs through loss of either neutral or charged moieties, with and without hydrogen and methyl radical migration, and both as high- and low-energy collision processes. For the doubly charged isobacteriochlorin, one-electron reduction with methyl loss occurs under ion bombardment and electrospray, through hypervalent pyrrolidinium radical formation.

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“…69 The estimates for water ice 70 indicated that an impact of a 2 keV Ar atom sputters ¾10 3 neutral and charged particles. While such ionization efficiency is comparable to the results of the gas-phase neutral molecule-ionizing particle collisions, the advantages of the bombardment process are in direct sputtering of ionic clusters and neutral clusters which can be ionized in subsequent events.…”

Section: Implications For the Atmosphere And Ecological Studiesmentioning

confidence: 99%

Low-temperature fast atom bombardment mass spectra of frozen nitric acid-water solution

et al. 1999

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Ionization in liquid secondary ion mass spectrometry (LSIMS)

Cited by 72 publications

References 137 publications

Comparison of Positive and Negative Ion Clusters of Methanol and Ethanol Observed by Low Temperature Secondary Ion Mass Spectrometry

Comparison of Positive and Negative Ion Clusters of Methanol and Ethanol Observed by Low Temperature Secondary Ion Mass Spectrometry

Cycloreversion and other gas‐phase reactions of neutral and cationic pyrrolidine‐fused chlorins and isobacteriochlorins under ion bombardment and electrospray

Low-temperature fast atom bombardment mass spectra of frozen nitric acid-water solution

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