Mineral: Naturally occurring solid with
a specific chemical composition and
Crystal structure.
F
Ca
Most common methods for determining composition and structure
are X-ray fluorescence and X-ray diffraction
X-ray fluorescence
(aka: energy dispersive spectroscopy (EDS), EDAX, WDS, etc.)
For elemental (chemical) analysis
DE = 5994.2 – 6.766
= 5987.4 eV
 = hc = 1236.57 ev*nm
E
5987.4 ev
= 0.206 nm = 2 Å (X-ray)
Scanning electron microscope (SEM)
imaging
X-ray
fluorescence
Electron diffraction
X-ray Diffraction
For crystal structure analysis and mineral identification
- end
V
+ end
Standard laboratory X-ray source (tube) operates by X-ray fluorescence
The introduction of phase differences produces a change in amplitude

Differences in the length of the path traveled lead to differences in phase
The waves will remain in phase if DD = ? = n
where n = whole number (1,2,3…
1
Y
X
1’
3
3’
q
A
B
X’
q
Y’
q q
d
F
q
q
G
E
sin Θ = opp/hyp
FE = d sinΘ
EG = d sinΘ
FE + EG = d sinΘ + d sinΘ = 2d sinΘ
n = 2d sinΘ
Bragg equation
Single crystal Diffraction Pattern
 = 2dsinΘ
X-ray
source
Crystal
Single crystal X-ray diffraction
Diffraction data on CCD detector
hkl
h’’k’’l’’
h’k’l’
Diffraction spots (reciprocal lattice spots) have different positions and intensities
In 3D
The intensity, Ihkl of a
diffraction peak is
determined by what
atoms are present and
where on the atomic
plane (i.e. electron
density). It is related
to a function called
the structure factor
Fhkl
Ihkl ∝ │Fhkl │ 2
Structure Factor
scattering
Fhkl    xyze 2i hx  ky lz dV
hkl
1
 ( xyz)  h k l Fhkl cos 2 (hx  ky  lz   hkl )
V
Goniometer
Powder (many crystal) X-ray diffraction
Point Detector
Multi crystal (Powder) Diffraction Pattern
X-Ray Powder Diffraction from a polycrystalline sample.
Our goal is a deeper knowledge of the fundamental
chemical, biological, and physical factors that govern the
reactivity and cycling of contaminants in the
environment.
Such information is essential for the development of
new (bio)remediation technologies and the remediation
of high level waste (HLW) and contaminated facilities.
#1 Speciation
Synchrotron radiation based techniques provide
unique capabilities to determine metal ion and organic
speciation and to characterize complex inorganic and
organic environmental solids in subsurface and waste
materials.
Lecture Outline
● General characteristics of synchrotrons and microprobe facilities
● Analytical methods available at synchrotron microprobe facilities,
with examples from our research on apatite and other minerals.
● mXRF
Surface structural controls on REE incorporation
in apatite, fluorite and diamond
● mXANES
Quantification of Eu oxidation states in apatite
● mEXAFS
Crystal chemistry of U and Th in apatite
● mXRD and time-resolved XRD
Phase transitions in apatite precursors
Advanced Photon Source (APS)
Argonne National Laboratory, Chicago, Illinois
(Sector 13: GSE-CARS)
SOLARIS
POLISH SYNCHROTRON RADIATION SOURCE
http://issrns2012.ifj.edu.pl/
NSLS
NSLS2
Brookhaven National Laboratory, Upton, New York
NSLS2 $912 million to design and build
National Synchrotron Light Source (NSLS)
Brookhaven National Laboratory, Upton, New York
(Beamlines X26A & X27B)
Booster
ring
LINAC
hutch
National Synchrotron Light Source
X26A and X27B NSLS
Experimental
Hutch
Beamline
Synchrotron storage ring and bending magnets
Sector 13 APS
Insertion devices: Wiggelers and Undulators
Beamline
Beamline
X-ray source spectral characteristics
Synchrotron Radiation Characteristics
High photon flux (increases sensitivity)
Spectral distribution (white beam)
Polarization (maximize of signal to noise)
Pulsed time structure (time resolved experiments 10-15s range)
Beam geometry (high spatial resolution)
X-ray (or e-)
Source
lab
synchrotron
X-ray
diffraction
Analytical
technique
X-ray
fluorescence
X-ray
Spectroscopy
(new to us)
Minimum detection limit
Minimum Sample size
Spatial resolution
Time for data collection
Monochromatic
X-ray
beam
White
X-ray
beam
2-Crystal Monochrometer (by diffraction)
NSLS X26A Experimental Hutch
NSLS X26A Beamline Configuration
KB Mirror-based hard X-ray microprobe
•
•
•
•
Kirkpatrick-Baez Microfocusing Optics
EDS Ge Array Detector
Canberra WDS detector
Bruker SMART 1500 CCD Area Detector
Energy Range Category:
•Monochromatic + White
•3-30 keV energy range
•Si(111) and Si(311) Channel-cut
Monochromators
Beam polarization – allows optimal signal to noise
Two KB-Mirror Based X-Ray Microprobes
Source
Beam
Size
(µm)
Flux @ 10
keV (ph/s)
µXRF
µXANES
µEXAFS
fCMT
NSLS
X26A
Bending
Magnet
(2.8 GeV)
10
1 x 109
1 ppm
10-100 ppm
1000 ppm 1%
10-100 ppm
APS
13-ID
Undulator
(7 GeV)
1
4 x 1011
100 ppb
1-10 ppm
100-1000
ppm
1-100 ppm
Beam
Line
mXRF
Micro-X-ray fluorescence
Elemental analysis with
● low minimum detection
● high spatial resolution
● coupled with other analyses
Synchrotron X-ray kicks our core electron from atoms in sample,
Higher energy core electron fills empty electron level, and ejects an x-ray of fixed
energy.
• Peak energies element diagnostic
• ~1ppm sensitivity in 30 pg particle (X26A NSLS)
Energy
Number of emitted photons
X-ray fluorescence mapping
SXRFMA
Dy
Optical photomicrograph
0.5 ppm
1.5 ppm
2.5 ppm
Trace element mapping nonequivalent growth sectors in
single crystal fluorite sections (area scans)
(Bosze & Rakovan, 2002)
Investigation of a single municipal waste fly ash particle
absorption image
XRF maps
XRD patterns
mXANES spectra
(From Somogyi et al., 2006)
mXRD
Micro- X-ray Diffraction
“Simultaneous” XRF/XAS/XRD
and Time Resolved XRD
Investigation of a single municipal waste fly ash particle
absorption image
XRF maps
XRD patterns
mXANES spectra
(From Somogyi et al., 2006)
apatite
monetite
brushite
2θ
Time resolved studies of nucleation and phase transformations
(Borkiewicz et al., in prep)
X-ray absorption spectroscopy (XAS)
XANES
EXAFS
X27
3-40 KeV
Unfocused White
4-28 KeV Focused
Monochromatic
Fermi
level
EF=0
peE = hn - Ebinding
t
IO
X-rays
IT
-mt
IT = IOe
IT
Incident X-ray E
1/IT
Energy
-
= ln(Io/I)
 can be collected from solids or liquids
XANES
EXAFS
photoelectron can be described in terms of E, , f, k
(Rakovan et al., 2002)
EXAFS Theory
k
k
Photoelectron scatters off of surrounding atoms and modulates the probability of
absorbing the incident synchrotron photon: EXAFS
Photoelectron
absorbing
atom
R0
Scattered
Photoelectron
Fourier Transform of (k)
• Similar to an atomic radial distribution function
–
–
–
–
Distance
Number
Type
Structural disorder
Theoretically calculated values
(we will use FEFF)
Parameters often determined
from a fit to data
fi(k) effective scattering amplitude
di(k) effective scattering phase shift
(k) mean free path
Ni degeneracy of path (CN)
S02 Amplitude reduction factor
(passive electron contribution)
i2 mean squared displacement (DW)
Rj path length
mXANES
Micro-X-ray Absorption Near Edge Structure Spectroscopy
● Oxidation state information for specific elements
● High spatial resolution
● Structural information in some cases
Eu L3-edge XANES
4.00E+00
Eu3+
Intensity
3.00E+00
2.00E+00
1.00E+00
Eu2+
0.00E+00
6.96E+03
6.97E+03
6.98E+03
6.99E+03
7.00E+03
-1.00E+00
Energy (eV)
(Rakovan et al., 2001)
U L3-edge XANES
2p3/2
6d t2g
2p3/2
6d eg
(Rakovan et al., 2002)
O3
?
2.81 Å
O1
O2
O1
2.40 Å
O3
O2
O2
Ca2+
O2 O1
O1
O2
O1
U6+
2.46 Å
2.06 Å
O3
?
2.06 Å
O2 O1
?
Ca1 site
(Rakovan et al., 2002)