Heavy Ion Induced X-ray Emission Research Articles

Particle-induced x-ray analysis using focused ion beams

In addition to the production of secondary electrons and secondary ions, characteristic x-ray emission may also result from ion/solid interactions and is the basis for the well-known analysis technique referred to as particle-induced x-ray emission. Characteristic x-rays may be emitted by either bombardment by MeV protons or heavy ions of a few keV. The advantage to heavy ions is that the x-ray yield is confined to the region near the surface defined by the collision cascade. An advantage of heavy ion-induced x-ray emission over electron-induced x-ray emission is that the Bremsstrahlung is potentially orders of magnitude lower. Thus, ion-induced x-ray spectra may provide for superior peak-to-noise ratios, and there-fore, offers trace element sensitivity compared with elec-tron-induced x-ray emission. In addition, the near surface ion/solid interactions also allow for the possibility of surface analysis or depth profiling. A Dual Beam instrument was used to collect focused ion beam-induced x-ray (FIBIX) spectra. The acquisition of characteristic x-rays from targets via FIBIX is demonstrated and compared with scanning electron microscopy-induced x-ray energy dispersive spectroscopy spectra and is consistent with the theory described above.

Thin film nanolaminate analysis by simultaneous heavy ion recoil and X-ray spectrometry

The methods of elastic recoil detection analysis (ERDA) and heavy-ion-induced X-ray emission (HIXE) were used simultaneously to separate heavy elements of adjacent masses in thin films. Nanolayered oxides containing Zr, Nb and Al were analyzed with beams of 79Br and 127I in the energy range of 32–53 MeV. Ratios of X-ray and recoil atom yields were determined as a function of beam energy for calibration samples. This allowed for the determination of the relative concentrations of elements of adjacent masses in other samples.

Trace Analysis by Heavy Ion Induced X-Ray Emission

Various K-, L- and M-shell X-ray production cross sections are measured for heavy ion impact on elements in the range Z2 = 13 to 83. The ion species range from Z1 = 10 to 36, and ion energies from 1 to 16 MeV are used. Enhanced cross sections are observed when the projectile K- or L- binding energy is similar to the energy of the target K-, L- or M-shell. This effect is used to improve the analysis sensitivity for selected elements. As an example trace analysis of Fe in glass with V, Mn, Co and Ni ions is investigated. Results are compared with proton induced X-ray emission analysis on the same samples. In these samples Fe-Kα X-ray production is similar for irradiation with 3 MeV protons and 14 MeV Ni ions. However the signal to background ratio is four times higher for the irradiation with Ni ions as compared to irradiation with protons. Advantages and drawbacks of heavy ion induced X-ray emission for quantitative analysis compared to proton induced X-ray emission analysis are discussed.

Heavy ion induced X-ray emission work at the TANDAR laboratory in Buenos Aires

The PIXE technique, using heavy ions beams, has been implemented at the TANDAR tandem facility in Buenos Aires. Mainly 16O beams in the bombarding energy range E = 30−50 MeV have been used and a systematic measurement of X-ray production cross sections has been performed. The technique has been applied to a variety of subjects, including environmental, biomedical and industrial problems.

Continuous backgrounds in heavy-ion induced X-ray emission

We report here continuous X-rays emitted from targets bombarded with Si 3+ ion beams of 1.435 MeV/amu over the range of target-atomic number Z T = 6–29. It is shown that the production cross sections of continuous X-rays can be well scaled with a function of the product of the K-shell radius of the united atom and the minimum transfer momentum of the projectile while MO X-ray spectra are scaled with the K X-ray energy of the united atom. These continuous X-rays may be interpreted as bremsstrahlung produced from a united atom which is formed by a projectile ion and a target atom during collision; we call this radiation united-atomic bremsstrahlung. In consideration of this continuous background, we discuss utility of a trace element analysis with high energy heavy-ion beams especially for analysis of chemical states by using a crystal spectrometer.

Carbon and silicon in travelling heater method grown semi-insulating CdTe

Carbon- and silicon-doped CdTe have been studied by charged particle activation heavy ion induced X-ray emission and secondary ion mass spectroscopy to determine the impurities present at low concentrations. Electrical characteristics have been investigated by thermally stimulated current and the Van der Pauw resistivity measurements, in order to correlate the impurity concentrations and electrical behaviours.

Comparison of various ions for use in heavy ion induced X-ray emission

The sensitivity and general usability of heavy ion induced X-ray emission for simultaneous elemental analysis with other ion beam methods has been investigated as a function of projectile atomic number. The variation of sensitivity and background radiation as a function of projectile energy was also studied. The ions selected consisted of 7 Li(8–18 MeV), 12 C(10–26 MeV), 16 O (12–32 MeV), 28 Si (16–28 MeV) and 80 Se (24 MeV). The ion energies used are also commonly employed in heavy ion backscattering spectrometry and elastic recoil detection analysis. The HIXE results of simultaneous determination of trace elements with Z = 15, 20, 22, 26 and 82 in thick samples were compared with the standard PIXE analysis by 3 MeV protons. To obtain information on any variations in the sensitivity on sample matrix, commercial standard samples of NBS River Sediment-2704, NBS Bituminous Coal-1632b, NBS Silicon-Aluminium alloy-87a and IAEA Animal Bone H-5 were used for which the elemental concentrations are known.

Chapter 5 Analysis by heavy ion induced X-ray emission

Chapter 5 Analysis by heavy ion induced X-ray emission

Trace element detection by high energy heavy ion induced X-ray emission

Argon ions from the Van de Graaf isochronous cyclotron for heavy ions (VICKSI) at Berlin were used to bombard targets containing various elements, originating from environmental and biological studies or prepared as calibrating standards. Emitted X-rays from various target backings were investigated. Background and detection sensitivity were compared with XRF and PIXE results on the same targets.

Trace analysis in cadmium telluride by heavy ion induced x-ray emission and by SIMS

The possibilities of using both selective heavy ion induced X-ray emission and secondary ion mass spectroscopy (SIMS), for the identification of impurities present at low concentrations in cadmium telluride are examined. The relative concentrations of the impurities along CdTe crystals have been determined by exciting the X-ray emission of the elements in several slices with Ar and Kr ions and by comparing the relative characteristic X-ray emission yields. As a consequence of the quasimolecular inner shell ionization mechanism in heavy ion-atom collisions, Ar and Kr ions allow a strong excitation of the main impurities seen by SIMS, namely Si, Cl and Ge, As, with only a minor contribution of Cd and Te. From the changes of the concentrations of the various impurities along the crystal, informations about segregation coefficients and compensation can be obtained.

Atomic Physics Vol 5

Richard Marrus, Michael Prior and Howard Shugart (eds) New York: Plenum 1977 pp xiii + 573 price $59.40 Volume 5 of the current series contains the texts of the invited lectures presented at the fifth international conference on atomic physics, held in Berkeley, California, in July 1976. The majority of the papers describe contemporary experimental work, the topics covered including parity violation; tests of quantum electrodynamics ; exotic atoms; laser and photoelectron spectroscopy; polarised electrons; diagnostic problems of large tokamaks; impurity effects in magnetically confined, high temperature plasmas; high Rydberg states; positronium experiments; and heavy-ion induced x-ray emission.

Trace elemental analysis by heavy ion induced x-ray emission

Trace elemental analysis by heavy ion induced x-ray emission