An upgraded ion source for a mass spectrometer

Zavilopulo, A. N.; Mironets, E. A.; Agafonova, A. S.

doi:10.1134/s0020441211060315

Cited by 7 publications

(4 citation statements)

References 5 publications

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“…The experiment was performed using a setup with an oil-free pumping unit described in detail earlier [4,16]. An MX-7304A type monopole mass spectrometer was used as an analytical instrument.…”

Section: Methodsmentioning

confidence: 99%

Ionization and fragmentation of valine molecules in the gas phase by electron impact

et al. 2021

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Formation of fragment ions due to single and dissociative ionization of the valine molecule (C5H11NO2) by electrons was studied by mass spectrometry. This is the first experimental massspectrometric measurement of total cross-section in arbitrary units of the valine molecule ionization by electron impact. The experiment was carried out using a setup with an MX-7304A monopole mass spectrometer in the range of mass numbers of 0-120 Da. Mass spectra of the molecules were studied at different vapor temperatures. The results obtained were compared with the mass spectra of the D-, L-, and DL-enantiomeric forms of the valine molecule taken from NIST and SDBS databases. The features of the processes of fragment ion formation of valine molecules by electron impact were analyzed in detail. Dynamics of the fragment ion yield in the range of the initial substance evaporation temperatures of 300-440 K was studied. The ionization potential of the valine molecule was measured (8.72 ± 0.22 eV) and calculated ab initio in the adiabatic approximation (9.367 eV). The ionization potential was estimated from the binding energy of the HOMO orbital of the neutral molecule. This is the first calculation of the single ionization cross section of the D-, DL-, and L-forms of this molecule in the Binary-Encounter-Bethe model and using the Gryzinski formula. The experimental cross section values at the threshold are normalized by the theoretical values in absolute units.

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Section: Methodsmentioning

confidence: 99%

Ionization and fragmentation of valine molecules in the gas phase by electron impact

et al. 2021

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“…The residual gas pressure in the vacuum chamber was 2 × 10 −5 Pa after heating the chamber for 24 h and 8 × 10 −5 Pa in the operating mode [25]. The choice of a monopole mass spectrometer MX7304A with a modernized ion source [32] as an analytical device was associated with its compactness and a possibility to be used not only to study gaseous objects, but also substances in the condensed state.…”

Section: Installation With a Monopole Mass Spectrometer (Imms)mentioning

confidence: 99%

“…Sulfur, selenium and tellurium mass spectra were measured at various energies of ionizing electrons, in a wide range of substance evaporation temperatures, and in an interval of mass numbers that was restricted only by the technical parameters of the mass spectrometer [32]. The measurement procedure consisted in the accumulation of multiple useful signals, so that the relative error did not exceed 0.5-1.5%.…”

Section: Mass Spectramentioning

confidence: 99%

Inelastic Processes of Electron Interaction with Chalcogens in the Gaseous Phase (a Review)

et al. 2020

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Complex research of elementary pair collision processes occurring when low-energy (0–70 eV) electrons pass through chalcogen (S, Se, Te) vapor has been carried out in the evaporation temperature intervals of those elements (T = 320÷700 K for sulfur, 420÷490 K for selenium, and 400÷600 K for tellurium). The vapor compositions of indicated elements are studied using the mass spectroscopy method. The radiation spectra are analyzed in the wavelength interval from 200 to 600 nm with the help of optical spectroscopy. Using highly monoenergetic electron beams, the total (integral) formation cross-sections for positive and negative S, Se, and Te ions are measured. It is found that, under the experimental conditions, the main components of chalcogen vapor are molecules containing 2 to 8 atoms. At the energies of bombarding electrons below 10 eV, the emission spectra mainly consist of bands of diatomic molecules, and, at higher energies (E > 15 eV), there appear separate atomic and ionic lines. At E = 50 eV, the lines of singly charged ions are the most intense ones. It is shown that the most effective reaction channel is the interaction of electrons with diatomic molecules of indicated elements, whereas other processes are mainly associated with the decay of polyatomic molecules. The excitation and ionization thresholds for interaction products are found by analyzing the energy dependences of process characteristics. Specific features are also observed in the energy dependences of the excitation and ionization functions. Doubly charged ions of diatomic sulfur molecules, as well as selenium and tellurium atoms, are revealed for the first time. The appearance of triply charged ions of diatomic sulfur molecules is also detected. The main contribution to the total (integral) effective ionization cross-section of both positive and negative ions is proved to be made by the interaction processes of electrons with diatomic molecules S2, Se2, and Te2. Besides the experimental research, a detailed theoretical study is carried out. Calculations with a theoretical analysis of their results are performed for the structural characteristics of homoatomic sulfur, Sn, selenium, Sen, and tellurium, Ten, molecules with n = 2÷8; namely, interatomic distances, ionization potentials, electron affinity energies, and dissociation energies. The energy characteristics are applied to calculate the appearance energies for singly and doubly charged ionic fragments of those molecules at the dissociative ionization. The obtained results are carefully compared with the available experimental and theoretical data.

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“…The experiments were performed on an installation equipped with a monopole mass spectrometer MX 7304A [10,16] with the mass resolution Δ = = 1 Da. A beam of PTCDA molecules generated with the help of an effusive-type source was directed into the ionization chamber of a mass spectrometer.…”

Section: Experimental Partmentioning

confidence: 99%

Electron-Impact Mass Spectrometry of PTCDA Molecules in the Gas Phase

Zavilopulo

Шпеник

2019

Ukr. J. Phys.

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The complete and dissociative ionizations of a 3,4,9,10-perylene-tetracarboxylic-dianhydride (C24H8O6, PTCDA) molecule in the gas phase have been studied, by using electron-impact mass spectrometry in an energy interval of 5–90 eV. The molecule is found to decay into the following fragment ions: the perylene core C20H8+ and its half C10H4+, as well as CO+, CO2+ , and O+ ions. The energy dependences of the cross-sections of the complete ionization of a PTCDA molecule and its fragment ions are analyzed. The energy of the complete ionization of a PTCDA molecule and the energies, at which its fragments appear, are determined. The temperature dependences of the formation of the most intensive fragment ions are measured, by using 80-eV electrons in a temperature interval of 320–500 K.

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An upgraded ion source for a mass spectrometer

Cited by 7 publications

References 5 publications

Ionization and fragmentation of valine molecules in the gas phase by electron impact

Ionization and fragmentation of valine molecules in the gas phase by electron impact

Inelastic Processes of Electron Interaction with Chalcogens in the Gaseous Phase (a Review)

Electron-Impact Mass Spectrometry of PTCDA Molecules in the Gas Phase

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