Argonne National Laboratory is managed by The University of Chicago for the U.S. Department of Energy

Spectromicroscopy in the 1–4 keV region: new opportunities for environmental scienceDavid Paterson1

Jay Brandes2, Jürgen Thieme3, Jörg Prietzel4, Ellery Ingall5, Ian McNulty1

1 Advanced Photon Source, Argonne National Laboratory2 The University of Texas at Austin3 Institute for X-ray Physics, University of Göttingen4 Chair of Soil Science, Technische Universität München5 Earth and Atmospheric Sciences, Georgia Institute of Technology, USA

2

X-ray microscopy and environmental science

X-ray microanalysis has and will continue to have a major impact onKnowledge of fundamental environmental processes, particularly in the food chainEffects of heavy metal contaminants and their biological remediation

Outline1. Motivation

a) High spatial resolutionb) Energy range

2. Introduction to 2-ID-B intermediate energy beamline and scanning x-ray microscope at APS

3. Environmental applicationsa) Phosphorus and oxygen bonding in marine organismsb) Sulfur speciation in soil

4. Summary and outlooknano-XRF and nano-XANES

3

Motivation

Many important processes occur at or across cell wall boundaries

20 nm length scale

Phosphorus, sulfur and metals are important trace elements in most processes

XRFSpectromicroscopy

4

Introduction to 2-ID-B intermediate energy beamline

Beamline designed to maintain high coherent flux– 5.5 cm period undulator brightest in 1–4 keV range

Major instruments– Scanning x-ray microscope using Fresnel zone plates– Coherent scattering and coherent diffraction imaging station– Upgrade of monochromator => 20X flux at key edges of P, S, Cl and

soon Ar, K and CaScience programs– Traditionally materials research and coherence/phase studies– Recently venturing into environmental and biological studies,

particularly µXRF and spectromicroscopy or µXANES with sub-micron spatial resolution, <100 nm

5

Characteristics• 1 – 4 keV• δ = 60 nm• 108 –109 ph/sContrast modes• Transmission• Phase contrast• Fluorescence• Micro-XANES

OSA

scan stage

sample

zone plate

APD or segmented detector

fluorescence detector

2-ID-B intermediate energy beamline and “nanoprobe”: vital statistics

Monochromaticity ~1000 typical, > 3000 peakCoherent area 50 μm 50 μmCoherent flux 2 105 ph/μm2 /s/0.1% BWFocused flux 4 107 ph/s/0.1% BW 50 nm spot

2 108 ph/s/0.1% BW 60 nm spot1 109 ph/s/0.1% BW 80 nm spot

6

Transmission– 2D imaging– Tomography – Phase contrast

Fluorescence Na -> P, S, Cl– Environmental and biological, highest

spatial resolution, coordinated with hard x-ray investigations

– Multi-layer coated spherical grating monochromator

10 µm

P

Cl

Patterned molecular conductorBEDT

Scanning x-ray microscopy 1–4 keV – 60 nm resolution

7

Helium Sample VLMtube

Fluorescence Photo-detector diode

Zoneplate

OSA

Fluorescence detection and sample mounting scheme

8

Phosphorus speciation in the marine environment

Phosphorus is a vital nutrient sustaining primary productivity in the world’s oceans Presence or absence of oxygen has a marked effect upon phosphorus release from particulate phasesBulk NMR studies show marine organic phosphorus consists of – phosphates (C-O-P bonding)– phosphonates (C-P bonding)

Distribution of each phosphorus type is highly variable over short length scales, possibly <200 nm?Chemical state mapping to separate the variety of phasesNew model of marine phosphorus cycling that takes into account micro-scale heterogeneity and speciation

9

Phosphorus fluorescence mapping of marine particulates

Absorption mapping of marine organic phosphorus particulates

– Low concentrations <1% make absorption XANES unsuitable

– High density regions are not necessarily phosphorus rich

– Use fluorescence yield

Fluorescence mapping to find phosphorus rich regions of interest

Collect fluorescence XANES spectra with nanoprobe

10

Phosphorus speciation in bulk spectra

Ultrafiltered Dissolved marine Organic Matter –80 m depth

Phytic acid phosphate

2-AminoEthylPhosphonate

P XANES spectra with 80 nm probePhosphorus speciation in marine particulates

11

Sulfur: why is it so important in soils?

S is highly reactive, exists in several oxidation states

S moves freely among lithosphere, hydrosphere and atmosphere

S is indispensable nutrient for plants and microorganisms

Speciation of S intimately linked with chemical state of soil

Changes are caused by pedogenic and anthropogenic processes and result in changes of soil properties

12

Animalmanures

and biosolids

Mineralfertilizers

Runoff anderosion

Leaching

Adsorbed ormineral sulfur

Plant residues

Plantuptake

Sulfate(SO4 )

Atmosphericsulfur

Elementalsulfur

Organicsulfur Immobilization

Mineralization Bacterial reduction

Bacterial oxidationOxidati

on

SO2 gas, SO4 rain

Reduced sulfur

Input to soilComponent Loss from soil

VolatilizationAtmosphericdeposition

--

The Sulfur Cycle

13

Study of sulfur species in soil

Importance of sulfur speciation in soil contrasts with the lack of microanalysis techniques available Wet chemistry and bulk techniques:total sulfur can only be distinguished into operationally defined fractions Not possible to assign a certain fraction to a specific sulfur species

Spectromicroscopy allows characterization ofassociations of soil colloids and soil micro habitatselemental co-localization, identify mineral and organic phasesstructure sulfur speciationphosphorus speciationdifferences within and between associations

14

0.0

500

1000

1500

2000

2500

0.0

2.465 2.47 2.475 2.48 2.485 2.49 2.495

Y

X

Fluorescence / a.u.

2.465 2.470 2.475 2.480 2.485 2.490 2.495 Photon Energy / eV

E = 2472.6 eV O

rganic disulfide S

Absorption edge E = 2477.5 eV

E = 2473.7 eV Thiol / organic m

onosulfide S

E = 2475.7 eV Sulfoxide S

E = 2480.5 eV Sulfone S

E = 2482.0 eV Sulfate S

J. Prietzel, J. Thieme,U. Neuhäusler, J. Susini,I. Kögel-Knabner,EJSS 54(2003) 1-11

Chemical analysis:IntegratedReduced ⇔ Oxidized

A typical XANES spectrum of sulfur species in soil

15

Fe-poor groundwater

Fe-rich groundwater

Silicate bedrock

Peat bogs

Soil

AB

CD

Sampling sites in the forest of Fichtelgebirge, Germany

Forest profile

16

Reduction

DC

BA

Sampling sites

Groundwaterinfluence

Soil horizons

Reduction

Hydrological gradient at sampling sites

17

Bulk/average spectra

Depth

B Srw anox (122/123)

Energy / eV2465 2470 2475 2480 2485 2490 2495

Sulp

hur R

OI /

I 0

0.0

0.2

0.4

0.6

0.8

1.0

C Gr anox (118/119)

Energy / eV2465 2470 2475 2480 2485 2490 2495

Sulp

hur R

OI /

I 0

0.0

0.2

0.4

0.6

0.8

1.0

C H1 anox (93/94)

Energy / eV2465 2470 2475 2480 2485 2490 2495

Sulp

hur R

OI /

I 0

0.0

0.2

0.4

0.6

0.8

1.0

C H2 anox (78/80)

Energy / eV2465 2470 2475 2480 2485 2490 2495

Sulp

hur R

OI /

I 0

0.0

0.2

0.4

0.6

0.8

1.0

D H2 anox (91/92)

Energy / eV2465 2470 2475 2480 2485 2490 2495

Sulp

hur R

OI /

I 0

0.0

0.2

0.4

0.6

0.8

1.0

D Aa anox (104/105)

Energy / eV2465 2470 2475 2480 2485 2490 2495

Sulp

hur R

OI /

I 0

0.0

0.2

0.4

0.6

0.8

1.0

A Of anox (101/103) and (106/107)

Energy / eV2465 2470 2475 2480 2485 2490 2495

Sulp

hur R

OI /

I 0

0.0

0.2

0.4

0.6

0.8

1.0

D H3 anoxic (76/77)

Energy / eV2465 2470 2475 2480 2485 2490 2495

Sulp

hur R

OI /

I 0

0.0

0.2

0.4

0.6

0.8

1.0A Oh anox (89/90)

Energy / eV2465 2470 2475 2480 2485 2490 2495

Sulp

hur R

OI /

I 0

0.0

0.2

0.4

0.6

0.8

1.0B H2 anox (82/81) and (83/81)

Energy / eV2465 2470 2475 2480 2485 2490 2495

Sulp

hur R

OI /

I 0

0.0

0.2

0.4

0.6

0.8

1.0

B Aeh anoxic (110/111)

Energy / eV2465 2470 2475 2480 2485 2490 2495

Sulp

hur R

OI /

I 0

0.0

0.2

0.4

0.6

0.8

1.0

B H1 oxic (139/140)

Energy / eV

2465 2470 2475 2480 2485 2490 2495

Fluo

resc

ence

inte

nsity

(a.u

.)

0.0

0.2

0.4

0.6

0.8

1.0

A Go Bv (61/62) and (63/64)

Energy / eV

2465 2470 2475 2480 2485 2490 2495

Fluo

resc

ence

inte

nsity

(a.u

.)

0.0

0.2

0.4

0.6

0.8

1.0

B Srd (65/66)

Energy / eV

2465 2470 2475 2480 2485 2490 2495

Fluo

resc

ence

inte

nsity

(a.u

.)

0.0

0.2

0.4

0.6

0.8

1.0

A Bv anox (39/40)

Energy / eV2465 2470 2475 2480 2485 2490 2495

Sulp

hur R

OI/I

0

0.0

0.2

0.4

0.6

0.8

1.0

A Aeh anox (36/38) and (37/38)

Energy / eV

2465 2470 2475 2480 2485 2490 2495

Fluo

resc

ence

inte

nsity

(a.u

.)

0.0

0.2

0.4

0.6

0.8

1.0

D Gor anox (47/48)

Energy / eV

2465 2470 2475 2480 2485 2490 2495

Fluo

resc

ence

inte

nsity

(a.u

.)

0.0

0.2

0.4

0.6

0.8

1.0

C Aa anox (45/43)

Energy / eV

2465 2470 2475 2480 2485 2490 2495

Fluo

resc

ence

inte

nsity

(a.u

.)

0.0

0.2

0.4

0.6

0.8

1.0

A B C D

Reduction

Reduction

Sampling sites

18

C H1 anox (93/94)

Energy / eV2465 2470 2475 2480 2485 2490 2495

Sulp

hur R

OI /

I 0

0.0

0.2

0.4

0.6

0.8

1.0

C H2 anox (78/80)

Energy / eV2465 2470 2475 2480 2485 2490 2495

Sulp

hur R

OI /

I 0

0.0

0.2

0.4

0.6

0.8

1.0

A Of anox (101/103) and (106/107)

Energy / eV2465 2470 2475 2480 2485 2490 2495

Sulp

hur R

OI /

I 0

0.0

0.2

0.4

0.6

0.8

1.0

A Oh anox (89/90)

Energy / eV2465 2470 2475 2480 2485 2490 2495

Sulp

hur R

OI /

I 0

0.0

0.2

0.4

0.6

0.8

1.0B H2 anox (82/81) and (83/81)

Energy / eV2465 2470 2475 2480 2485 2490 2495

Sulp

hur R

OI /

I 00.0

0.2

0.4

0.6

0.8

1.0

B Aeh anoxic (110/111)

Energy / eV2465 2470 2475 2480 2485 2490 2495

Sulp

hur R

OI /

I 0

0.0

0.2

0.4

0.6

0.8

1.0

B H1 oxic (139/140)

Energy / eV

2465 2470 2475 2480 2485 2490 2495

Fluo

resc

ence

inte

nsity

(a.u

.)

0.0

0.2

0.4

0.6

0.8

1.0

A Aeh anox (36/38) and (37/38)

Energy / eV

2465 2470 2475 2480 2485 2490 2495

Fluo

resc

ence

inte

nsity

(a.u

.)

0.0

0.2

0.4

0.6

0.8

1.0

C Aa anox (45/43)

Energy / eV

2465 2470 2475 2480 2485 2490 2495

Fluo

resc

ence

inte

nsity

(a.u

.)

0.0

0.2

0.4

0.6

0.8

1.0

Reduction

Reduction

Analysis of catena

19

1 2 3

4 550X50 µm2, 400X400 pixels0.5 sec dwell/pixel

1 – transmission2 – sulfur3 – aluminium4 – silicon5 – overlay

MAPS (S.Vogt)

Spatially resolved data, e.g. B H2 anoxic

20

Summary and future work for sulfur studies

Bulk sample studiesSuccessfully applied spectromicroscopy to soil samplesKeeping strictly anoxic conditions for the samples is criticalThe hydrological gradient is clearly reflected in the bulk spectra

OutlookBulk sample studies

Continue to study soils with extremely low concentrations of sulfurExtraction of single sulfur species from spectraComparison of bulk spectra from site to site

Spatially resolved data:Extraction of single sulfur species from spot to spotComparison from spot to spotComparison with bulk

Goal: Understand the fate of sulfur as a function of hydrological gradient

21

Conclusion and future directions

Motivation for high resolution µXRF and µXANES in environmental, biological and nano-materials studiesBeamline 2-ID-B intermediate energy scanning x-ray microscope

– Provides unique combination of high spatial resolution and energy resolution in the 1–4 keV energy range

– Combined with rapid sample changeover, in situ studies, hydrated samples and correlated hard x-ray analysis

Example studies– Phosphorus and oxygen in marine organisms and particulates– Sulfur cycle in soils

Future directionsInstrumentation

– Better detection schemes (increased solid angle)– Faster acquisition and better energy resolution– Better Fresnel zone plates to approach 10 nm resolution

Science?– Resolve sub-cellular structures and processes at and across the cell wall– Nano-XRF and nano-XANES

Opportunity to open new frontiers in environmental science

22

Acknowledgements

Jay Brandes & Ellery IngallUniversity of Texas at Austin & Georgia Institute of Technology

Jürgen Thieme & Jörg Prietzel, Nora TyufekchievaUniversität Göttingen & Lehrstuhl für Bodenkunde, TU München

Ian McNulty & Martin de JongeAdvanced Photon Source

Steve SuttonUniversity of Chicago

Ken Kemner & Shelly KellyArgonne National Laboratory

B. Twining, S. Baines, M. KissellSUNY Stony Brook

This work is supported by DFG under contract Pr 534/4-1 U. S. Department of Energy, Office of Science, Basic Energy Sciences, under contract W-31-109-ENG-38.

Thanks to ICXOM – Organizers.

23

Techniques and instrumentation – future directions

Spatial resolution– Better zone plates

Fluorescence– Current 0.5 sec dwell– Desire 0.05 sec– Fly scan fluorescence mapping

Detectors– Solid angle and multi element– Faster acquisition rates - DSP 10 mm

24

Undulator Source

Spherical Mirror

Entrance Slit

Exit Slit

Spherical Grating

Zone Plate

31.120 12.150 3.500 8.0105.500 0.006

Beamline opticsHorizontal plane (m)

Minihutch Sample – Optics – Detector

2-ID-B@APS intermediate-energy beamline

25

Segmented detector – Integrating, voltage to multichannel ADC– 2 msec dwell, sub-msec achievable– Diatom @ 1790 eV, fly scan– 25 nm pixel, 1000 X 1000 pixels, 40 min

Benjamin Hornberger, Michael Feser, Chris JacobsenSUNY Stony Brook

10 µm10 µm

600 µm

Phase contrast imaging

26

C Aa anoxic sampling

Energy / eV

2460 2465 2470 2475 2480 2485 2490

Fluo

resc

ence

inte

nsity

/ a.

u.

0.0

0.2

0.4

0.6

0.8

1.0

C Aa oxic sampling

Energy / eV

2460 2465 2470 2475 2480 2485 2490

Fluo

resc

ence

inte

nsity

/ a.

u.

0.0

0.2

0.4

0.6

0.8

1.0

Time lag:

P. Kjeldsen 1993

Ddt

2

61⋅=

Material Diffusion Thickness Time lagcoefficient /µm /sec/cm2/s

Polyethylene 0.30.10-7 4 0.89Polypropylene 0.29.10-7 4 0.92Silicon 0.15.10-30 0.1 1.11.1020

Anoxic versus oxic sampling