Ion Formation in MALDI:  The Cluster Ionization Mechanism

2003 ◽  
Vol 103 (2) ◽  
pp. 427-440 ◽  
Author(s):  
Michael Karas ◽  
Ralf Krüger
Keyword(s):  
Ionization Mechanism ◽  
Ion Formation ◽  
Cluster Ionization

Ion Formation in MALDI: The Cluster Ionization Mechanism

ChemInform ◽  
2003 ◽  
Vol 34 (18) ◽  
Author(s):  
Michael Karas ◽  
Ralf Krueger
Keyword(s):  
Ionization Mechanism ◽  
Ion Formation ◽  
Cluster Ionization

Aromatization of C2-C6 Aliphatic Hydrocarbons on Copper-Containing ZSM-5 Zeolites

1992 ◽  
Vol 57 (12) ◽  
pp. 2553-2560
Author(s):  
Zdravka Popova ◽  
Katia Aristirova ◽  
Christo Dimitrov
Keyword(s):  
Copper Content ◽  
Acid Strength ◽  
The State ◽  
Aliphatic Hydrocarbons ◽  
Bronsted Acid ◽  
Ion Formation ◽  
Brönsted Acid ◽  
Wide Range ◽  
Carbenium Ion ◽  
Acid Centers

The aromatization of a wide range of model aliphatic and cycloaliphatic hydrocarbons (ethene, ethane, propene, n-hexane, 1-hexene, methylcyclopentane, cyclohexane, cyclohexene) on copper-containing NaZSM-5 and HZSM-5 zeolites has been investigated. It was established that the degree of aromatization is related to carbenium ion formation and depends on the acid strength and copper content of zeolite. Experiments with copper-containing samples reduced prior to use indicated the possibility to enhance the selectivity to aromatization. The change of the state of Cu2+ ions during catalytic experiments confirmed the assumption about participation of Cu0 simultaneously with the Bronsted acid centers in the dehydrogenation/hydrogenation steps.

Ferrous ion formation by ferrioxamine prepared from aged desferrioxamine: A potential prooxidant property

1994 ◽  
Vol 16 (6) ◽  
pp. 733-739 ◽  
Author(s):  
John M.C. Gutteridge ◽  
Gregory J. Quinlan ◽  
Jason Swain ◽  
James Cox
Keyword(s):  
Ferrous Ion ◽  
Ion Formation

An efficient method for 3, 4‐dihydroisoquinolinium ion formation, leading to a facile introduction of nucleophiles

2020 ◽  
Author(s):  
Makoto Shimizu ◽  
Takato Kawamura ◽  
Shinya Fukumoto ◽  
Isao Mizota ◽  
Yusong Zhu
Keyword(s):  
Efficient Method ◽  
Ion Formation

scholarly journals Surface acoustic wave nebulization improves compound selectivity of low-temperature plasma ionization for mass spectrometry

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Andreas Kiontke ◽  
Mehrzad Roudini ◽  
Susan Billig ◽  
Amarghan Fakhfouri ◽  
Andreas Winkler ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Low Temperature ◽  
Acoustic Wave ◽  
Surface Acoustic Wave ◽  
Ionization Mechanism ◽  
Low Temperature Plasma ◽  
Ambient Conditions ◽  
Temperature Plasma ◽  
Plasma Ionization ◽  
Surface Acoustic Wave Nebulization

AbstractMass spectrometry coupled to low-temperature plasma ionization (LTPI) allows for immediate and easy analysis of compounds from the surface of a sample at ambient conditions. The efficiency of this process, however, strongly depends on the successful desorption of the analyte from the surface to the gas phase. Whilst conventional sample heating can improve analyte desorption, heating is not desirable with respect to the stability of thermally labile analytes. In this study using aromatic amines as model compounds, we demonstrate that (1) surface acoustic wave nebulization (SAWN) can significantly improve compound desorption for LTPI without heating the sample. Furthermore, (2) SAWN-assisted LTPI shows a response enhancement up to a factor of 8 for polar compounds such as aminophenols and phenylenediamines suggesting a paradigm shift in the ionization mechanism. Additional assets of the new technique demonstrated here are (3) a reduced analyte selectivity (the interquartile range of the response decreased by a factor of 7)—a significant benefit in non-targeted analysis of complex samples—and (4) the possibility for automated online monitoring using an autosampler. Finally, (5) the small size of the microfluidic SAWN-chip enables the implementation of the method into miniaturized, mobile LTPI probes.

scholarly journals 3D optical spectroscopic study of NGC 3344 with SITELLE: I. Identification and confirmation of supernova remnants

2019 ◽  
Vol 488 (1) ◽  
pp. 803-829 ◽  
Author(s):  
I Moumen ◽  
C Robert ◽  
D Devost ◽  
R P Martin ◽  
L Rousseau-Nepton ◽  
...  
Keyword(s):  
Supernova Remnants ◽  
Flux Ratio ◽  
Large Magellanic Cloud ◽  
Emission Lines ◽  
Ionization Mechanism ◽  
H Ii Regions ◽  
Nearby Galaxy ◽  
Galactocentric Distance ◽  
Ionized Gas ◽  
Diffuse Ionized Gas

ABSTRACT We present the first optical identification and confirmation of a sample of supernova remnants (SNRs) in the nearby galaxy NGC 3344. Using high spectral and spatial resolution data, obtained with the CFHT imaging Fourier transform spectrograph SITELLE, we identified about 2200 emission line regions, many of which are H ii regions, diffuse ionized gas regions, and also SNRs. Considering the stellar population and diffuse ionized gas background, which are quite important in NGC 3344, we have selected 129 SNR candidates based on four criteria for regions where the emission lines flux ratio [S ii]/H α ≥ 0.4. Emission lines of [O ii] λ3727, H β, [O iii] λλ4959,5007, H α, [N ii] λλ6548,6583, and [S ii] λλ6716,6731 have been measured to study the ionized gas properties of the SNR candidates. We adopted a self-consistent spectroscopic analysis, based on Sabbadin plots and Baldwin, Phillips & Terlevich diagrams, to confirm the shock-heated nature of the ionization mechanism in the candidates sample. With this analysis, we end up with 42 Confirmed SNRs, 45 Probable SNRs, and 42 Less likely SNRs. Using shock models, the confirmed SNRs seem to have a metallicity ranging between Large Magellanic Cloud and 2×solar. We looked for correlations between the size of the confirmed SNRs and their emission lines ratios, their galaxy environment, and their galactocentric distance: We see a trend for a metallicity gradient among the SNR population, along with some evolutionary effects.

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