17)X-ray Spectrometry– HVC Capacitor, HV Ceramic Capacitor to build All kinds of X-ray machine.
TW-EPMA data, the scavenging rate of atmospheric S species and
reactive N-oxides by dry deposition of sea-salt particles could be
estimated. Sea-salt particles probably play an important role as
scavengers of acidic species in the coastal Antarctic regions.
Continental aerosols contain significant amounts of coarse bio-
genic and organic particles. While TW-EPMA could provide direct
information on these particles, Worobiec et al. ( J25 ) presented
an alternative preparation method for single-particle EPMA using
a conventional EDX detector with Be window. The organic and
biogenic particles were impregnated with a heavy metal (Ru), and
the resulting better backscattered electron contrast allowed the
tracing of these types of particles with d > 0.7 ím by automated
EPMA. The method is especially beneficial, when only a Be-
windowed EDX detector is available.
In addition to microparticles, automated EPMA is capable of
detecting microinclusions in a substrate material. Nuspl et al. (J26 )
studied nonmetallic microinclusions in steel on a metallographi-
cally prepared surface area. A new offline evaluation method has
been developed to classify the large amount of inclusions ( 1000/
sample) and calculate specific size and shape data. Alumina,
common spinel, sulfide, and oxisulfide inclusions could be identi-
fied as dominant inclusion types in low-carbon steel.
As a forensic application, Cardinetti et al. (J27 ) demonstrated
the capabilities of EPMA with the X-ray mapping technique for
identification of gunshot residues. Pb -Sb-Ba aggregates can also
originate from nonfirearm sources; the morphology and the
presence of other elements is not characteristic to the source of
the aggregates. Using the X-ray mapping method, gunshot
residues showed the same Pb -Sb-Ba distribution, but other
environmental occupational aggregates had different plaques of
Pb, Sb, and Ba. The X-ray mapping technique can offer a new
fundamental evaluation parameter in analysis of gunshot residues
with EPMA.
The determination of Th/U concentration ratios in monazite
microinclusions by EPMA offers a high-resolution dating of small
minerals. Cocherie et al. (J28 ) pointed out that a significant
number of individual spot analyses is required to reach such
precise information (i.e., more than 30-40 data). Using the
examples of monazites from three migmatites and one granite,
the authors advised selection of the most efficient method of age
calculation according to the U and Th geochemistry of the grains
or grain domains.
PIXE. There is an increasing trend for applying nondestructive
analytical techniques for biological samples. The capabilities of
PIXE for metal analysis of proteins were studied by da Luz et al.
(J29 ) using a 2.25-MeV scanning proton microbeam. No radiation
damage was noticed in glyoxalase II for currents up to 500 pA.
Glyoxalase II served also to demonstrate the ability of PIXE to
determine the metal stoichiometry even for protein concentrations
similar to 60 pM. They recommend simultaneous STIM measure-
ments allowing lateral density determination. Gontier et al. (J30 )
applied micro-PIXE in association with STIM and RBS to char-
acterize different epidermis models on a microscopic scale.
Reconstituted epidermis obtained from airlifted cultures, epidermis
of mice foot sole, and human forehead skin grafts transplanted
into mice are the models investigated and compared with human
native skin. Very similar inorganic ion patterns were observed in
all epidermis, suggesting comparable permeability barrier mech-
anisms and validating their use as alternative approaches to native
skin experimentation.
Another interesting application of PIXE was reported by
Graham et al. (J31 ): elemental analysis of particles encapsulated
by silica aerogel collectors. In 2006, the Stardust spacecraft will
return to Earth with cometary and perhaps interstellar dust
particles embedded in silica aerogel collectors for analysis in
terrestrial laboratories. In preparation for the return, analogue
particles were implanted into a keystone of silica aerogel.
Concentrations of elements with Z > 11 could be determined using
PIXE in the encapsulated particles; therefore, PIXE and other ion
beam techniques will be used for analysis of interstellar particles
collected by Stardust.
Carbon nanotubes were extensively investigated recently,
being potential materials for hydrogen storage technology for
energy applications. Naab et al. (J32 ) demonstrated the utility of
PIXE and ERDA to quantitatively determine impurities in C
nanotubes over a wide range of atomic numbers. Despite the
difficulty in mounting the samples of a powdery aggregate, reliable
and accurate measurements of impurity concentrations could be
achieved. ERDA allowed the direct measurement of H impurities
in C nanotubes.
PIXE is routinely used for elemental analysis of atmospheric
aerosols, but it usually provides concentrations only for elements
with Z >10. However, information on major, light elements is
important for atmospheric studies. An Italian group (J33 ) proposed
a combination of PIXE with in-vacuum particle elastic scattering
analysis (PESA) for determining H, C, N, and O concentrations.
Aerosols collected on Teflon filters were found to be ideal for
PESA, but the DL of PIXE for high-Z elements increased due to
the Compton ç-ray background caused by the F content. The
coupling of PIXE and PESA allowed the “mass closure”: the sum
of the concentrations of all the elements detected by the two
techniques resulted equal to the gravimetric mass within 20% for
all the analyzed samples of each aerosol fraction collected in a
small industrial town near Florence. Borbe´ ly-Kiss et al. ( J34 )
investigated the episodic appearance of Saharan dust in the
Hungarian aerosol using PIXE concentration data of aerosols
collected in the period of 1991-2000. The time series of concen-
tration ratios, Ti/Ca, Si/Al, Al/Ca, Ti/Fe, Si/Fe, Ca/Fe, generally
accepted as regional signatures of Saharan dust, as well as air
mass backward trajectories or aerosol index data from satellites
were used as tools for selecting Saharan dust episodes. During a
nine-month period, nearly 50 local episodes could be assigned to
Saharan sources.
XAS.An interesting application of XAS was reported by Ueda
et al. (J35 ), to O, Mg, Si, S, and Fe in the galactic interstellar
medium (ISM). The authors utilized X-ray absorption features of
three bright low-mass X-ray binaries, GX 13 +1, GX 5-1, and GX
340+0. The comparison of Si K-edge XANES of ISM and ground
experimental data of Si compounds indicated that most of the ISM
Si exists in the form of silicates. S K-edge measurements indicated
that a significant fraction of S exists in the gas phase. From the
absorption spectra, column densities of Mg, S, Si, and Fe could
be derived.
Materials science is one of the major application fields of XAS.
Evaluating both EXAFS and XANES spectra, quantitative structural
analysis can be performed. Monesi et al. (J36 ) reported on
quantitative structural investigation of hole-doped perovskites such
as La
1-x
CaxMnO3
, presenting special magnetic and magnetotrans-
port properties. It is commonly accepted that the local atomic
structure around Mn ions plays a crucial role in determining these
peculiar features. The recently developed MXAN code was used
to achieve a quantitative structural refinement of the Mn K-edge
XANES of the compounds of interest. The quantitative XANES
analysis provides topological information not directly achievable
from EXAFS data analysis. The same approach was used by
Benfatto et al. (J37 ) for XANES spectra at the Zn K-edge of
systems formed by phospholipid Langmuir-Blodgett multilayers
in the presence and in the absence of myelin basic protein and in
two hydration conditions. Their results showed that the metal
interacts with both the phospholipid heads of the substrate and
the myelin basic protein.
A wide range of applications were reported on time-resolved
XAS in the review period. Yaakobi et al. (J38 ) studied the
properties of laser-shocked metals on a nanosecond time scale
using a laser source-based EXAFS measurement. In Ti shocked
near 0.5 Mbar with a 3-ns laser pulse, the EXAFS modulation
damping was much higher than expected from the increase in
temperature. This could be explained by the R-Ti to ö-Ti phase
transformation known to occur around 0.1 Mbar from longer time
scale measurements.
Time-resolved XAS is mostly applied in the field of catalysis.
For example, Rose et al. (J39 ) investigated the electrochemical
formation of â-hydride and â-deuteride phases of a C-supported
Pd nanoparticle catalyst using time-resolved, in situ ED XAS. The
composition of the hydride and deuteride phases formed was
determined using the lattice parameters obtained by fitting the
ED XAS data, giving compositions of PdH0.83 and PdD
0.63 , which
are consistent with the â-hydride and -deuteride phases. Toward
the development of a useful mechanism for H storage, Nikitin et
al. ( J40 ) studied the hydrogenation of single-walled C nanotubes
with atomic H using core-level photoelectron spectroscopy and
C K-edge XAS. The authors found that atomic H creates C-H
bonds with the C atoms in the nanotube walls, and such C-H
bonds can be completely broken by heating to 600°C. A reversible
hydrogenation of 65 ( 15 at. % of C atoms was detected in the
single-walled C nanotubes.
Because of the increased importance of chemical characteriza-
tion light elements in airborne particulate matter, a number of
environmental applications of XAS employed soft X-rays. Braun
and co-workers (J41 ) investigated diesel soot under various engine
load conditions with NEXAFS spectroscopy at the C K-edge.
Information about relative amounts of C double bonds (CdC,
CdO) and C single bonds (CsH, CsOH, COOH) could be
obtained with this technique.
To select appropriate sites for nuclear waste, information on
the chemical speciation and environmental mobility of actinides
is important. Denecke et al. (J42 ) studied U-speciation in a tertiary
sediment from a waste disposal natural analogue site using micro-
XRF and micro-XANES recorded in a confocal geometry on a bore
core section. Their results showed that U was present as a
tetravalent phosphate, which was associated with As(V). Arsenic
was found to be present in either As(V) or arsenopyrite form in
the whole sample. The authors proposed a hypothesis for the
mechanism of U-immobilization, where arsenopyrite acted as
reductant of groundwater-dissolved U(VI), leading to precipitation
of less soluble U(IV).
Standards.Sturgeon et al. ( J43 ) reported on the certification
of a new fish otolith reference material for trace element analysis.
This certified reference material (CRM) will be of interest to those
laboratories requiring quality assurance of measurements of bulk
elemental composition of otoliths and other marine aragonites.
The new CRM (FEBS-1) was prepared from 4.5 kg of dried
saggital otolith harvested from red snapper ( Lutjanus campecha-
nus), ball milled and sieved to <200 mesh, homogenized, irradi-
ated, bottled into 1-g aliquots, and certified for major, minor, and
trace element composition. Certified values for seven elements
(Ba, Ca, Li, Mg, Mn, Na, Sr) are reported; reference values for
Cd, Cu, Ni, Pb, and Zn are also provided; these elements were
considered to be not certifiable because of the large component
of uncertainty contributed by homogeneity.
Quantitative EPMA including light elements needs appropriate
CRMs, especially for C and N. Saunders et al. (J44 ) addressed
certification of reference materials for these two elements.
Cementite (Fe3
C), a line compound, was chosen as a suitable
material for C and ç′-Fe
4N for N. The compounds were produced
by, respectively, carburising or nitriding pure Fe under carefully
controlled conditions. Particular emphasis is placed on a homo-
geneity study, background correction methods, and methodology
validation using these reference materials.
Imre Szalo´ kigraduated in physics and mathematics from Kossuth
University of Debrecen, Hungary, in 1978. He received his Ph.D. in XRF
spectroscopy and nuclear physics in 1983. Since that time he has been a
researcher and assistant professor in the Institute of Experimental Physics
at the University of Debrecen (Kossuth University). His research activity
involves studies of fundamental quantification problems of XRS analysis
and its applications in geology, medical physics, and environmental and
material science. Since 1999, he has worked frequently at the University
of Antwerp on methodological developments in EPMA and XRF tomog-
raphy.
Ja´ nos Osa´ n graduated in 1992 as a physicist at the Eo¨tvo¨s Lora´ nd
University in Budapest, Hungary. He received a Ph.D. degree in
environmental physics and biophysics at the Semmelweis University,
Budapest, Hungary, in 1997. Since then, he has worked as a senior
scientist at the Health and Environmental Physics Department of the KFKl
Atomic Energy Research Institute. He has been involved in methodological
development and application of modern X-ray microanalytical methods
in environmental analysis. His main activities are connected with EPMA,
micro-XRF, and micro-XANES.
Rene´ Van Grieken received his Ph.D. degree in chemistry from the
University of Ghent in Belgium. After that, he was visiting professor at
Florida State University. Since 1974, he has beeen Professor of Analytical
and Environmental Chemistry at the University of Antwerp. He is co-
director of the Micro- and Trace Analysis Centre of this university, which
involves some 80 researchers, studying the methodology of various
microanalysis and trace analysis techniques, including different forms of
XRS, and their application in, for example, environmental analysis.