16)X-ray Spectrometry– HVC Capacitor, HV Ceramic Capacitor to build All kinds of X-ray machine.
APPLICATIONS
Sample Preparation. The dried spot technique is an effective
method for elemental analysis using micro-XRF. However, the
current technology, using microliter volume spots, suffers from
lack of repeatability and long sample preparation times. Miller
and Havrilla (J1 ) proposed a new nanoliter dried spot sample
preparation method, producing uniform spots in a reproducible
way. The minimum detectable concentrations for the nanoliter
spots were in the ppb range with the ability to detect picogram-
level masses, with a sample drying time of seconds to minutes.
This new sample preparation method has the potential for use in
situations where sample availability is limited. Fusion is a widely
used sample preparation technique for XRF. However, volatiliza-
tion of flux mixtures during fusion can affect analytical results.
Loubser et al. (J2 ) studied the thermal behavior occurring during
the formation of lithium borate glasses. The results showed that
above 1050 °C lithium borate fluxes volatilize, which could lead
to inaccurate analytical results.
ED-XRF. The availability of noncryogenic ED detectors
induced a growing number of applications in planetary science
using on-board and remote-sensing XRF spectrometers. CheMin
(J3 ) is a miniature XRD/XRF instrument that is included in the
payload of the Mars 2009 Mars Science Laboratory mission. A
portable CheMin prototype was built to test the capability of the
instrument for remote in situ mineralogical characterization of
geological materials. The instrument was successfully deployed
at a variety of Mars analogue sites.
Among the wide range of biological applications, Shi et al. (J4 )
reported a successful XRF study of a large range of metallo-
proteins. A high-throughput method for measuring the transition
metal content based on quantitation of XRF signals was used to
analyze 654 proteins selected as targets by the New York
Structural GenomiX Research Consortium. Over 10% showed the
presence of transition metal atoms in stoichiometric amounts;
these totals as well as the abundance distribution are similar to
those of the Protein Data Bank. Bioinformatics analysis of the
identified metalloproteins in most cases supported the metallo-
protein annotation; identification of the conserved metal binding
motif was also shown to be useful in verifying structural models
of the proteins.
Nie et al. (J5 ) studied the long-term Pb metabolism in the
human body based on a set of XRF bone lead data. The data set
includes the bone Pb concentration of 539 occupationally exposed
workers, of whom 327 were measured twice in five years. The
bone Pb concentrations of both cortical bone (tibia) and trabecular
bone (calcaneus) were obtained by
109
Cd ç-ray-induced XRF
measurements. The histories of blood Pb concentration for these
workers were used to regulate the input of the model. After
organizing the data set into five age groups, a simplified model
was successfully applied to estimate the Pb-transfer rates between
blood and Pb compartments for these age groups.
Micro-XRF. The improvement of the lateral resolution of
brilliant X-ray microbeams induced numerous applications of
í-XRF in medical and biological studies. Waern et al. ( J6 ) studied
the intracellular distribution of transition metals in V79 Chinese
hamster lung cells treated with subtoxic doses of the organo-
metallic anticancer complexes Cp2
MCl2
, where Cp is è-(5)-
cyclopentadienyl and M is Mo, Nb, Ti, or V, by í-SRXRF. While
significantly higher concentrations of Mo and Nb were found in
treated cells compared with control cells, distinct differences in
the cellular distribution of each metal were observed. The results
agree with independent chemical studies that have concluded that
the biological chemistry of each of the metallocene dihalides is
unique. Zoeger et al. (J7 ) studied the distribution of Pb and Zn in
slices of human bone by í-SRXRF using a focused beam of 15
ím in diameter. Pb was found to be mostly located at the outer
border of the cortical bone in various samples. Ratios of Pb
intensities of cortical and trabecular bone varied from 0.027 for
hip head to 0.408 for proximal tibia. Ca, Zn, and Sr distributions
were also recorded simultaneously, showing a remarkable as-
sociation between the Pb and Zn contents. Harris and co-workers
(J8 ) studied the distribution of Cr and endogenous elements within
A549 human lung adenocarcinoma epithelial cells, following
treatment with Cr(VI) (100 íM, 20 min or 4 h) by í-SRXRF of
single freeze-dried cells. After the 20-min treatment, Cr was
confined to a small area of the cytoplasm and strongly co-localized
with S, Cl, K, and Ca. After the 4-h treatment, Cr was distributed
throughout the cell, with higher concentrations in the nucleus
and the cytoplasmic membrane. This time dependence cor-
responded to nearly 100 or 0% clonogenic survival of the cells
following the 20-min or 4-h treatments, respectively, and could
potentially be explained by a new cellular protective mechanism.
The intracellular reduction of Cr(VI) to Cr(III) was confirmed by
micro-XANES of intracellular Cr hotspots.
Peeters et al. ( J9 ) reported an interesting electrochemical
application of í-SRXRF. Different electrochemical surface modi-
fication techniques were compared with special attention to the
immobilization of Co(II) tetrasulfonated phthalocyanine tetra-
sodium salt (Co(II)TSPc) on Au electrodes. A methodology of
scanning í-XRF for nondestructive, quantitative characterization
of CoTSPc deposition on Au electrodes was described that can in
general be used for thin-film characterization. Different electro-
chemical behavior was observed depending on the degree of
dimerization of the CoTSPc molecules.
In the last two years, several applications of í-XRF to environ-
mental microparticles were reported. A Japanese group (J10 )
reported on an on-site combination of SEM and í-SRXRF, where
the SR beam was introduced into the SEM chamber. Detailed
topographic observation by SEM and sensitive elemental analysis
byí-SRXRF could be jointly performed inside the SEM chamber
in this setup. The combined technique was applied to Kosa (yellow
duststorm sand) particles. Complex microstructures were ob-
served on the surface of a fragment of the Tatahouine meteorite.
Lemelle et al. ( J11 ) applied chemical characterization of these
microstructures, searching for microorganisms. N, P, and S
compositions, including the S speciation, were investigated using
SEM, EPMA mapping, and scanning X-ray microscopy (SXM). A
few 2- ím-thick filaments, partly covered by patches of calcite, were
observed by SEM. The EPMA maps show that the calcite-free
portions of the filaments have low but constant contents of N, S,
and P. The SXM maps were recorded at 2473.5, 2478, and 2482.2
eV, which energies are respectively characteristic for amino acid-
linked S, sulfite (SO
3
2-
), and sulfate (SO
4
2-
). The portions of the
filaments detected by EPMA are also those that are enriched in
amino acid-linked S. The authors proposed that the observed
microstructures are dehydrated microorganisms. Uzonyi et al.
(J12 ) reported on combined í-PIXEand í-SRXRF techniques for
the characterization of impact materials collected at the well-known
Barringer meteor crater. Elemental maps were recorded and
concentrations were determined by í-PIXE for the major con-
stituents of the samples. The í-SRXRF technique was used for
complementary measurements of medium- and high- Z elements,
especially the siderophilic ones (especially, Cr, Co, Ni, and Pt
group elements) that are generally applied for the identification
of meteoritic impact events. The applied microanalytical methods
allow the identification of the impact objects and also yield
information on the projectile and the impact process itself.
Diamond inclusions are of particular research interest in mantle
petrology and diamond exploration as they provide direct informa-
tion about the chemical composition of upper and lower mantle
and about the petrogenetic sources of diamonds in a given deposit.
Sitepu et al. ( J13 ) reported on the nondestructive in situ identifica-
tion and characterization of mineral inclusions in diamonds using
í-SRXRF at a focused spot size of 4 -5 ím. High-resolution maps
of Ti, Cr, Fe, Ni, Cu, and Zn for natural diamond grains were
recorded, along with quantitative í-SRXRF analysis of select
chemical elements in exposed kimberlite indicator mineral grains.
The distribution of diamond inclusions inside the natural diamond
host could be mapped usingí-SRXRF, and their Cr content could
be quantified.
TXRF. TXRF has recently become a standard method for the
measurement of the atomic surface density of elemental contami-
nation on Si wafer surfaces. Ge substrates are recently being
reconsidered as a candidate material for the replacement of Si
substrates in advanced semiconductor devices. For this reason,
several authors dealt with TXRF analysis of metallic contaminants
on Ge surfaces. Hellin et al. ( J14 ) reported on two types of TXRF
analytical methods for this purpose. Detection limits (DL) of direct
TXRF analysis on Ge wafers were at the 10
10
at./cm
2
level, a factor
between 1 and 3 higher than on Si wafers, exclusively caused by
differences in the background intensity. Additionally, a precon-
centration procedure based on the droplet sandwich etch method
was developed, allowing an order of magnitude decrease of DL
compared to direct TXRF. The same research group (J15 )
presented the extension of the methodology of vapor-phase
decompositionsdroplet collectionsTXRF spectrometry (VPD-DC-
TXRF) for metallic contamination analysis toward Ge substrates.
Since the Ge wafers surface is not hydrophobic after the VPD
treatment, the contact angle could be significantly increased using
a concentrated HCl solution. As a matrix removal procedure, Ge
could be volatilized at low temperatures as GeCl
4 by the addition
of HCl. The full VPD-DC-TXRF method has been applied on
intentionally contaminated Ge wafers and proved to be very
accurate.
Another great application field for TXRF implies biological
studies. Biological organic samples are frequently analyzed by
TXRF after digestion procedures. Marco and Hernandez-Caraballo
(J16 ) summarized direct analysis of biological samples. Different
procedures of sample preparation and calibration to approach the
direct analysis were evaluated: slurry sampling, Compton peak
standardization, in situ microwave digestion, in situ chemical
modification, and direct analysis with internal standardization.
Woelfl et al. (J17 ) applied TXRF for determination of trace
elements in planktonic microcrustaceans. The recently developed
dry method allowed a nondestructive quantification of the trace
element content of minute biological samples with a dry weight
of 3 -50íg. Three different freshwater microcrustaceans were
sampled, from a natural, uncontaminated lake and from an artificial
reservoir slightly contaminated by drainage water from a Cu mine.
The results showed that both content and bioaccumulation of trace
metals were significantly different between the microcrustaceans
from the two lakes.
To¨ro¨k et al. (J18 ) employed TXRF in conjunction with near-
edge X-ray absorption fine structure (NEXAFS) to investigate the
chemical state of N-compounds in aerosols. The aerosol samples
of different size fractions were deposited on Si wafer surfaces in
a cascade impactor. Molar ratios of ammonium and nitrate could
be determined based on a linear combination of standard spectra
of NaNO
3 and (NH
4
)
2SO
4
. The DL enabled an analysis of aerosol
samples taken in 10 min with acceptable accuracy. Applicability
of the technique to real aerosol samples has been used to compare
N oxidation states in suburban and rural aerosols.
EPMA. In addition to the traditional applications, several
authors reported on the capabilities of EPMA for analysis of
multilayered samples. Using a combination of EPMA with surface
removal by the focused ion beam (FIB) technique (J19 ), depth
profile analysis in the submicrometer range was achieved. Owing
to the low detection limits of the WDX technique, monolayers
with mass coverages of 0.05 í g/cm
2
could be detected. FIB
allowed the milling of defined geometries on the nanometer scale,
so that very shallow bevels with exactly defined angles in relation
to the surface could be obtained. Calibrated WDX measurements
along the bevel delivered quantitative concentration depth profiles
for a multilayered sample used in optical data storage. Ultrathin
(<10 nm) film thicknesses of Ge, Sr, Ag, and Au deposited on Si
substrates were determined by EPMA using Monte Carlo simula-
tions ( J20 ). The variable incident electron energy method was
applied, ranging from 4 to 20 keV. The maximum relative
difference between results from EPMA and other techniques did
not exceed 5%.
Based on the recent advances of thin-window EPMA (TW-
EPMA) allowing at least semiquantitative determination of light
elements down to B, it was extensively applied in the field of
atmospheric chemistry. Laskin et al. (J21 ) reported field evidence
of complete, irreversible processing of solid CaCO
3-containing
particles. The formation of nitrates from individual calcite and sea
salt particles was followed as a function of time, and compositional
changes of individual particles were observed using TW-EPMA.
ESEM was utilized to determine and demonstrate the extreme
hygroscopic behavior of calcium nitrate particles found in some
of the samples. Hoffman et al. (J22 ) studied the phase and
behavior of NaNO
3
particles at different relative humidity. Changes
in NaNO
3 particles during hydration were studied using ESEM
and TW-EPMA. Mixtures of NaNO
3
and NaCl, which are typical
of partially processed sea salt particles, were also studied. Their
results showed that NaNO
3
particles exist as unusual metastable,
amorphous solids at low relative humidity; they undergo continu-
ous hygroscopic growth with increasing relative humidity. In
addition to basic atmospheric chemistry studies, individual particle
analysis by TW-EPMA was also applied to large aerosol sampling
campaigns. Niemi et al. (J23 ) applied TW-EPMA on coarse aerosol
samples collected in the Atlantic marine boundary layer between
the English Channel and Antarctica. The major particle types
observed were fresh sea salt, sea-salt particles reacted partly or
totally with sulfuric acid or nitric acid, Mg -sulfate, Ca -sulfate,
mixed aluminosilicates and sea salt, aluminosilicates, Ca-rich
particles, and Fe-rich particles. The Cl depletion of sea-salt
particles was strongest when air masses arrived from the direction
of anthropogenic pollution sources. The fractions of Mg-sulfate
particles were found to be high near Europe. These particles were
probably formed as a result of fractional recrystallization of sea-
salt particles in which Cl was substituted by sulfate. Hara et al.
(J24 ) applied TW-EPMA to individual sea-salt particles collected
at coastal Antarctic regions for a better understanding of sea-salt
chemistry. Their results indicate that more sea-salt particles were
modified in fine particles (0.2ím < d < 2 ím) through
heterogeneous reactions mainly with gaseous S species in the
summer and reactive nitrogen oxides in the winter and spring. In
particular, sea-salt particles in the coastal Antarctic atmosphere
may be modified by heterogeneous reactions with not only SO2
and H
2SO
4 but also volatile S species derived from bioactivity on
the ocean surface during the summer. Based on the single-particle