Magnetic Mass Analyzer Research Articles

Experimental comparison of time-of-flight mass analysis with magnetic mass analysis

A series of experiments was carried out in which both a magnetic analyzer (mass separator) and a time-of-flight (TOF) spectrometer were used for ion charge/mass spectral analysis of the ion beam formed by a dc Bernas ion source made for semiconductor implantation. The TOF analyzer was a detachable device that provides rapid analysis of charge-to-mass composition of moderate energy ion beams. The magnetic analyzer was a massive device using a 90 degrees -sector bending magnet with radius of the central orbit of 35 cm. Comparison of these two methods for measuring ion beam composition shows good agreement.

RF plasma emitter of diagnostic neutral beam injector for the W7-X stellarator

A diagnostic neutral beam injector is being developed in the Budker Institute of Nuclear Physics (Novosibirsk, Russia) for the neutral particle diagnostics in the Wendelstein 7-X stellarator in Greifswald (Germany). The injector ion source is planned to provide a proton beam with a current of up to 10 A, energy up to 65 keV and pulse duration up to 10 s. The plasma emitter provides the ion current density about 120 mA/cm 2 at the plane of plasma grid within a circle of 16 cm in diameter. This paper describes the results of the development of the radio-frequency plasma emitter for the ion source. The results of the first experiments with ion beam extraction are presented. Using a four-grid ion optical system permitting the extraction of ion beam current up to 2.4 A, the beam composition was measured by Doppler shift spectroscopy and magnetic mass analyzer. According to the measurement for the fixed beam energy of 50 keV and beam current variable up to 2.4 A, the full-energy beam specie is about 80% for the required ion current density of the plasma emitter.

Formation, deposition and examination of size selected metal clusters on semiconductor surfaces: An experimental setup

An instrument designed to investigate the chemical behavior of size selected metal clusters on semiconductor surfaces is described. The clusters are formed using laser vaporization, mass selected in a magnetic mass analyzer and deposited on TiO 2 substrates under UHV conditions with impact energies ranging from ≤1 to >100 eV/atom. Intensities of mass selected Au n + and Ag n + clusters range from 0.03 to 3 nA. Intensity, beam focusing and deposition energy are discussed. Once deposited on the surface, the clusters are investigated using scanning tunneling microscopy (STM) and/or temperature programmed desorption (TPD). Examples are presented showing STM images of Au 5 deposited on a clean rutile titania surface and of the TPD of propene from TiO 2.

Preparative separation of a multicomponent peptide mixture by mass spectrometry

We report on the first multiplex preparative separation by mass spectrometry of bio-organic molecules in the 200-350 Da mass range that is typical for synthetic drugs. A five-component mixture consisting of two di- and three tripeptides has been separated by mass using a specially designed mass spectrometer. The instrument for preparative separations consists of an electrospray ionization (ESI) source, ion transfer optics, an electrostatic sector, and an inhomogeneous-field magnetic mass analyzer that achieves linear mass dispersion of ion beams. Protonated peptides produced by electrospray were separated, nondestructively landed on a 16-channel array of dry collector plates, and reconstituted in solution. The preparation procedures and the instrumental conditions have been optimized to maximize the ion currents. The significant features of the special mass spectrometer are high ion currents and simultaneous separation and collection of mixture components.

Induction of Extracellular Matrix Synthesis in Normal Human Fibroblasts by Anthraquinone Isolated from Morinda citrifolia (Noni) Fruit

In previous studies we found that Morinda citrifolia (Noni) fruit extract up-regulated biosynthesis of type I collagen and glycosaminoglycans in primary cultures of normal human fibroblasts. The objective of this study was to identify the active ingredients in Noni fruit extract. An active single compound having a type I collagen-stimulating effect was isolated and identified as 1,4-dihydroxy-2-methoxy-7-methylanthraquinone by nuclear magnetic resonance, infrared, and mass analysis. It was revealed that anthraquinone showed significantly increased elaboration of procollagen type I C-terminal peptide and glycosaminoglycans and reduced expression of the collagenase matrix metalloproteinase-1 dose-dependently in human dermal fibroblasts. Furthermore, in a clinical trial, a nano-emulsion containing anthraquinone predominantly increased the dermal type I procollagen in nude mouse skin. These results suggest that anthraquinone derived from Noni extract is a good candidate for use as a new anti-wrinkle agent due to its strong induction of biosynthetic activity of extracellular matrix components.

Production of Si + and Cl + ion beams from a Freeman type ion source using low toxicity and non-corrosive vapours as source gas

A method is proposed for production of Si + and Cl + ions in Freeman type ion sources using low toxicity and non-corrosive vapours of hexamethyldisilane ((CH 3) 3SiSi(CH 3) 3) and carbon tetrachloride (CCl 4), respectively. These source materials can be used without expensive and complicated safety systems required for silane and chlorine source gases. Experimental X-ray photoelectron spectroscopy results show that in the case of (CH 3) 3SiSi(CH 3) 3 vapour used as the ion source gas, the ion beam, after using standard magnetic field ion mass analysis for mass 28, contains about 62% of 28Si + ions. It is assumed that the molecular ions C 2H 4 + with the same mass 28 are the main component of the remaining 38% of this ion beam. In the case of the use of CCl 4 vapour as ion source gas and magnetic field mass analysis set for mass 35, a pure Cl + beam is observed; there are no other ions of mass 35 that can be formed from the source gas. The same system when used with water vapour as a source gas can produce pure ion beams of O + and/or H + ions without adverse effects produced in the ion source by oxygen gas (oxidation) or typical safety problems with a hydrogen gas supply (explosive).

Radial focusing of ion beams in a mass analyzer with an electrostatic lens and a sector-shaped inclined-wall magnetic prism

The ionic and optical properties of an inclined-wall magnetic mass analyzer with electrostatic direction focusing of ions in a nonuniform (r−1) magnetic field were studied. A condition for ion focusing in the radial plane was derived, and the basic parameters of the mass analyzer were determined.

Low Energy Implantation of Boron with Decaborane Ions

AbstractFormation of p-type shallow junctions for future generations of Si devices will require ion implantation of B at very low energies (< 1 keV). An alternative to implantation of monomer ions at very low energy is implantation of large molecular ions at a higher energy. In an ion beam of decaborane (B10H14) each of the B atoms carries only 9% of the ion kinetic energy. We have examined ionization properties of decaborane and built an experimental ion source and an implantation apparatus with magnetic mass analysis. Analyzed decaborane ion beams with energies from 2 to 10 keV and beam currents of several microamperes were obtained. Si samples were implanted with decaborane ions and the implanted dose measured by current integration was compared with B content obtained by nuclear reaction analysis. Experiments with electrostatic beam deflection show that the large ions survive the transport in the implanter environment and that neutralization is negligible. During implantation, the retained B dose is reduced in comparison with the nominal implanted dose due to sputtering. Dose loss is greater at 200 eV compared to 500 eV. The properties of decaborane ion beams and the prospects of using them for shallow implantation of B into Si are discussed.

Effect of residual gas on the ion charge distribution in vacuum arc discharge plasmas

A magnetic mass analyzer and time-of-flight mass spectrometer are used to study the effect of the pressure and type of residual gas on the ion charge distribution in the plasma of an arc discharge with a cathode spot. The possibility of ionizing a substantial fraction of the gas atoms in this type of discharge is pointed out.

Ion species measurement of high current metal ion beams extracted from a multicusp ion source

Ion charge state and impurities extracted from a multicusp ion source have been studied with the use of a magnetic momentum mass analyzer. Impurities contained in high current metal ion beams are crucible materials (such as Al2O3, BN, Y2O3, C) and high melting point materials (such as Mo, Ta, W). To reduce these impurities, the dependence of the impurity on the arc discharge voltage has been investigated experimentally. Amounts of impurities and multicharged ions are decreased with arc discharge voltage. For example, at the arc discharge voltage of 60 V, aluminum ion beam contains 1% impurities and 4% multicharged ions, and at the arc discharge voltage of 20 V, impurities and multicharged ions are less than 1% in all. High-purity single-charged metal ion beams have been obtained.

Aluminum cluster ions generated by a liquid metal ion source

Aluminum cluster ions Al+n are generated by a liquid metal ion source and observed up to n=10 using a magnetic mass analyzer. Relative integrated intensities of cluster ions as a function of n show a distinct step between n=7 and 8, which is explained by the electronic shell model. Cluster ions have lower kinetic energy compared with monomer ions which are accelerated to the full energy. Moreover, energy spread of cluster ions is larger than that of monomer ions. These results are attributed to the difference of ion formation mechanism. In addition to the fully accelerated monomer ions, at a high ion current region there also appear monomer ions with energy deficit which are formed in the same process as cluster ions.

Cluster ions ejected from an LiMg alloy liquid metal ion source: observation of Mg 2+2 and Mg 2+3

Ions ejected from a liquid metal ion source of an LiMg (10 atom %) alloy have been investigated by using a magnetic mass analyzer. In addition to singly charged homonuclear Li + n ( n ≤ 9) and Mg + n ( n ≤ 4) and heteronuclear Mg m Li + n ( m, n ≤ 2) clusters, doubly charged diatomic and triatomic Mg clusters are observed. Discussion is focused on the observability and the formation mechanism of the doubly charged small Mg clusters. A postionization process is suggested for the formation of the doubly charged clusters.

Generation of an intense metal-ion beam by a pulsed ion diode

Intense pulsed metal-ion beams (∼100 keV, ∼1 kA, 0.5 μs, Pb and Cu) were generated by a pulsed magnetically insulated ion diode driven by a long-pulse Marx generator. The ion current density exceeded the Child–Langmuir value by a factor of 50. The ion beams were extracted from either an anode plasma produced by electron bombardment on a metal anode or by a vacuum-arc metal-plasma source. Metal-ion beams rich in high-energy multi-ionized ions and also impurity ions of H+, C+, and O+ were measured by a Thomson-parabola ion spectrometer and a magnetic mass analyzer. The amount of impurity ions were reduced by conditioning of the anode surface. A design was considered to develop an intense metal-ion source with a total ion current of 1 kA, an ion energy of 100–200 keV, a pulse width of 10 μs, and repetition rate of 10 Hz, all of which correspond to a 100 mA steady-state metal-ion beam.

Abundance of Na cluster ions ejected from a liquid metal ion source

Sodium cluster ions Na+ n withn ranging up to 25 have been observed from a liquid sodium ion source by using a magnetic mass analyzer. Ion intensity as a function of cluster size showed distinct steps and local maxima atn=3, 5, 11, 13 and 19 (magic numbers), and a pronounced odd-even alternation. The features in the ion abundance curve are attributed to the relative stability of cluster ions. The observed magic numbers are only partially explained by the electronic shell model, indicating need to include a consideration of atomic structure in a cluster.

Magic Numbers in a Mass Spectrum of Lithium Clusters Emitted from a Liquid Metal Ion Source

Lithium ion clusters Lin+ with n ranging up to 19 have been observed from liquid lithium ion sources by using a magnetic mass analyzer. The ion intensity as a function of cluster size showed local maxima at n=7, 9, 13, and 19. Only n=9 and 19 can be explained by the electronic shell model, which successfully predicts magic numbers of other alkali metal (Na, K) clusters. On the other hand, the geometrical atom packing model explains the observed magic numbers except for n=9.

Development of an intense pulsed metallic ion beam source

Intense pulse metallic ion beams (Al/sup +/, Cu/sup +/, and Pb/sup +/) were produced by a magnetically insulated ion diode having a metal anode. Metal ion plasmas on the anode could be generated through enhanced electron bombardment by using a radial cathode. The energy, current density, and duration time of the lead ion beam were 30 approximately 140 keV, approximately 7.5 A/cm/sup 2/ (total ion current >or=0.5 kA), and 800 ns, respectively. The ion current density exceeded the space-charge-limited current by a factor of 50. The lead ions in the first-to-sixth states of ionization were detected by a Thomson-parabola ion-spectrometer together with light loss, such as C/sup +/ and O/sup +/. The ratio of the ion current of heavy metals to the total ion current was measured using a magnetic mass analyzer with a charge collector. The ratio was about 90% for a lead ion beam and 20 approximately 50% for Al and Cu ion beams. >

Evaluation of a low-cost, automated pyrolysis-mass spectrometer

A low-cost, automated pyrolysis-mass spectrometer based on a quadrupole mass analyser (Prutec PYMS system) was evaluated by analysing three sample sets (orange juices, pectins and micro-organisms) and by comparison with results obtained on a manual pyrolysis-mass spectrometer based on a magnetic mass analyser (VG Gas Analysis, Pyromass 8–80). Reproducibility of replicate analyses was better on the PYMS system for orange juices and pectins and was comparable with the Pyromass for micro-organisms. Discrimination of samples was always achieved by the PYMS system and, if the data analysis was restricted to m/z 51–140, the PYMS discrimination was superior to that obtained on the Pyromass for orange juices and pectins but was inferior for micro-organisms. The use of a wider mass range in the data analysis on the Pyromass 8–80 improved the discrimination of orange juices and pectins but impaired the discrimination of micro-organisms.

Ion Source for the Juelich SNQ-Project

We report on the construction of a hydrogen ion source to provide a proton beam of about 150 mA at an energy of 50 keV. The source is of the magnetic multipole type. The ion density in the extraction plane at a discharge current of 76 A has been determined to be 200 mA/cm2 from the ion saturation current of a Langmuir-probe. The proton fraction in the plasma is as high as 74% at this operation condition as measured by a magnetic momentum mass analyser. The proton fraction in the plasma is related to plasma parameters via a scaling equation to give reasonable agreement.

High magnetic field, large-volume magnetic multipole ion source producing hydrogen ion beams with high proton ratio

In order to enhance the proton fraction in hydrogen ion beams, a high magnetic field, large-volume magnetic multipole ion source has been designed and tested. The plasma source is made of a water-cooled rectangular copper chamber, which is surrounded by a set of mild steel strips and samarium–cobalt magnets arranged in a continuous line-cusp geometry. The magnetic field at the inner wall surface is 2.7 kG. This strong magnetic field enables us to enlarge the chamber volume without increasing the ion loss area. Large plasma volume and small ion loss area increase the ion confinement time and enhance the proton yield. The proton fraction in the beams, as measured by both a magnetic momentum mass analyzer and a optical spectrometer, is found to be more than 90% at an ion beam current of 28 A ( j=250 mA/cm2). This source is also operated with a weak magnetic field (∼0.6 kG) by replacing the samarium–cobalt magnets with AlNiCo magnet, in which case the proton fraction decreases to 80%. These experimental values are in good agreement with the values predicted by a simple scaling equation of the proton ratio on the plasma volume and the ion loss area.

Low-energy electron dissociative attachment processes in HgBr2

Br- formation in HgBr2 has been studied by means of two cross-beam electron impact spectrometers, one equipped with a trochoidal electron monochromator and a magnetic mass analyser and the other one equipped with two 127 degrees electrostatic energy filters and a quadrupole mass analyser. It is found that the Br- cross section in the energy range 0-7 eV exhibits two peaks, at zero energy and 4.15 eV respectively. The energy distributions of Br- ions are obtained in the energy range of the second process, different interpretations are discussed.