Modernization of the MI1201 mass spectrometer for studying the electron-molecule interaction processes at low electron energies

Vukstich, V. S.; Imre, A. I.; Snegursky, A.V.

doi:10.1134/s0020441211020205

Cited by 22 publications

(12 citation statements)

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“…Експериментальні дослідження здійснювалися з використанням мас-спектрометричної методики (див. її детальний опис у роботах [7,8]). Відмітимо, що вона забезпечує можливість дослідження утворення іонних фрагментів вихідних молекул у діапазоні мас 1-720 а.о.м.…”

Section: експериментunclassified

“…Відмітимо, що вона забезпечує можливість дослідження утворення іонних фрагментів вихідних молекул у діапазоні мас 1-720 а.о.м. з високим розділенням (m/∆m = 1100, тут m -атомна маса) та чутливістю (~10 -16 A) і пов'язана з використанням техніки пучків, що перетинаються, з наступним аналізом продуктів реакції за допомогою модернізованого магнітного мас-спектрометра [7]. Пучки молекул формувалися за допомогою ефузійного джерела з омічним нагрівом, що забезпечувало концентрацію досліджуваних молекул на рівні 10 10 см -3 .…”

Section: експериментunclassified

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Electron Impact Fragmentation of the Glycine and Methionine Molecules

Снігурський¹,

Тамулієне²,

Romanova³

et al. 2013

Sci.Herald.Uzh.Univ.Ser.Phys

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Експериментально та теоретично досліджено фрагментацію молекул гліцину (C 2 H 5 NO 2) та метіоніну (C 5 H 11 NO 2 S) електронами малих енергій. Основний акцент зроблено на механізмах утворення позитивно заряджених фрагментів вихідних молекул однакового хімічного складу. Головну увагу приділено енергетичним характеристикам виходу іонних фрагментів. Проаналізовано геометричні параметри перегрупування первинних молекул. Ключові слова: гліцин, метіонін, мас-спектр, потенціал появи, енергія зв'язку.

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Section: експериментunclassified

Electron Impact Fragmentation of the Glycine and Methionine Molecules

Снігурський¹,

Тамулієне²,

Romanova³

et al. 2013

Sci.Herald.Uzh.Univ.Ser.Phys

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“…[10]) as the massseparator unit enabling the fragments of electron molecule interaction to be identied. controlled by a thermocouple allowing the temperature dependences of the fragment yields to be determined.…”

Section: Methodsmentioning

confidence: 99%

“…A specially designed three-electrode electron gun provided an electron current I e = 30−50 µA within a wide (0150 eV) energy range with the energy spread < 0.3 eV (full width at the half-maximum of the beam energy distribution) [10]. The experimental appearance potentials were determined by means of a tting technique based on the least-squares method approximation using the MarquardtLevenberg algorithm described in detail in our previous studies (see.…”

Section: Methodsmentioning

confidence: 99%

Production of Similar Fragments from the Glycine, Alanine, and Methionine Amino Acid Molecules under Low-Energy Electron Impact

et al. 2015

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Production of the ionic fragments of the same chemical composition due to a low-energy electron impact on the glycine, alanine, and methionine amino acid molecules has been studied both experimentally and theoretically. The mass-spectrometric technique was applied to detect the above ionic fragments within the 1720 a.m.u. mass range with the ±0.25 a.m.u. resolution, while the density functional theory based theoretical approach allowed the relevant species to be identied and the mechanisms of their production to be claried. A special attention has been paid to analysis of the geometrical structures of the molecules under study as well to nding the appearance potentials of their fragments with the accuracy of ±0.1 eV.

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“…The measurements were performed with a commercial magnetic mass spectrometer of the MI 1201 type, which was signifi cantly modified by linking to an IBM PC with a digital system of mass spectrum sweep and data acquisition control [6]. The modified mass spectrometer exhibited high temporal stability detection (zero level drift, 1 mV/h) and high sensitivity of the ion current detection (detection threshold, ~10 -16 A).…”

mentioning

confidence: 99%

Determination of the atomic composition of isobaric ions in the mass-spectrometric study of the L-asparagine monohydrate

2012

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Investigation of the mechanisms of structural changes in biomolecules caused by their interaction with electron beams is an important task [1], since these molecules are highly sensitive to ionizing radia tion and this knowledge is of basic significance for solving problems of mutagenesis and radiation protec tion. Amino acids are among the simplest biologically relevant organic molecules and serve as convenient model systems for the investigation of radiation induced damage. L asparagine (L Asn) belongs to the class of the 20 most common amino acids and is stable in both anhydrous and hydrated states under standard conditions. In recent years, the crystalline L aspar agine monohydrate C 4 H 8 N 2 O 3 · H 2 O (LAM) and its complexes have been extensively studied as new potential nonlinear optical materials [2][3][4][5], which implies the need for evaluating the thermal stability and radiation resistance of this compound under working conditions. The data on the dissociative ionization of amino acids are very restricted and rather contradictory, which is mostly related to the fact that these biomole cules undergo fragmentation under experimental con ditions, due to both the interaction of molecules with incident electrons during dissociative ionization and their thermal destruction upon heating, which is nec essary for sample conversion into the gaseous state.This Letter presents the first results of our experi mental investigation of the mass spectrum of LAM ionized by electron impact, with an attempt at exactly determining the atomic composition of the fragment ions within the mass range of m/z = 12-46 amu.The charged products of the fragmentation of the LAM molecules under electron impact were studied by the method of mass spectrometry that is capable of both identifying the interaction products and tracing the dynamics of their formation. The measurements were performed with a commercial magnetic mass spectrometer of the MI 1201 type, which was signifi cantly modified by linking to an IBM PC with a digital system of mass spectrum sweep and data acquisition control [6]. The modified mass spectrometer exhibited high temporal stability detection (zero level drift, 1 mV/h) and high sensitivity of the ion current detection (detection threshold, ~10 -16 A). A digitized scheme of pulsed sweep control ensured scanning of the mass spectrum at a minimum step of Δm 0 .0001 amu. The mass spectra were obtained at a con stant electron energy of 70 eV and recorded using both an analog channel of ion current measurements (spec tral sweeps) and a digital channel with point by point scanning at a 0.004 amu step and the input signal inte gration time of 0.1 s.The typical normalized mass spectrum of LAM in the 10-90 amu range measured at an ion source tem perature of 160°C is presented in the figure. The ion yield (relative abundance) is plotted on a semilogarith mic scale because the peak intensities range within two orders of magnitude. As can be seen, the mass spec trum consists of separate groups of peaks, each occu pying an ...

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Modernization of the MI1201 mass spectrometer for studying the electron-molecule interaction processes at low electron energies

Cited by 22 publications

References 1 publication

Electron Impact Fragmentation of the Glycine and Methionine Molecules

Electron Impact Fragmentation of the Glycine and Methionine Molecules

Production of Similar Fragments from the Glycine, Alanine, and Methionine Amino Acid Molecules under Low-Energy Electron Impact

Determination of the atomic composition of isobaric ions in the mass-spectrometric study of the L-asparagine monohydrate

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