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BL14W1 X-ray Absorption Fine Structure Spectroscopy (XAFS) Beamline

1.     Introduction

Beamline BL14W1 specializes in x-ray absorption fine structure (XAFS). It has been open for users since May 2009. It is tunable by two types of double crystal monochromator for covering photon energy from 4.5 keV to 50 keV. K-edge absorption of Titanium up to Lanthanum can be studies. Other heavier atomic species can be investigated via L edges. The bulk of our scientific program is in catalysis, materials science and environmental research.

 

2.     Beamline Layout

         

 

                            

3.     Techniques

Ø  Transmission XAFS

Transmission mode is suitable for sample having x-ray absorbing atoms (absorbers) at high density (>5%wt).

Ø  Fluorescence XAFS

Fluorescent mode is best applied to dilute sample where “self-absorption effect” is negligible.

 

Setup for transmission XAFS and fluorescence XAFS

Ø  Grazing incidence XAFS

 

Setup for grazing incidence XAFS

4.     Optics

Ø  Double Crystal Monochromator (DCM)

 

Crystal type

Photon energy range

Si(111)

4.5 keV - 18 keV

Si(311)

8.5 keV – 50 keV

DCM crystal and energy range

 

Ø  Collimation mirror (Rh coated)

Ø  Toroidal focusing Mirror (Rh coated)

Ø  Harmonic rejection mirror

Coated crystal

Photon energy range

Rh

6.5 keV -12 keV

Ni

5.5 keV -8.0 keV

Si

3.5 keV -6.0 keV

Blank

> 12 keV

Coated crystal of harmonic rejection mirror and energy range

5.     Detectors

Ø  Oxford ion chamber

Ø  Lytle detectors

Ø  32-element Canberra/XIA Ge detector system

 

Oxford ion chamber and 32-element Ge detector

Ø  4-element silicon drift detector

 

 

4-element silicon drift detector

6.     Additional Equipment

Ø  5 dimension precision stage

Ø  Low temperature sample environment system

Ø  High temperature sample environment system

Ø  Grazing incidence-XAFS sample stage

 

7.     Beamline Controls and Data Acquisition

EPICS and LabVIEW

 

8.     Beamline Specifications

Source

Wiggler

Monochromator type

Si(111) and Si(311)

Energy range

4.5 -18 keV (Focused)

4.5- 50 keV (Unfocused)

Energy Resolution(ΔE/E)

1.5´10-4@10keV@Si(111)

0.5´10-4@10keV@Si(311)

Flux (photons/sec)

1´1013phs/s@10keV@300 mA (Si(111), focused)

Beam size at sample

0.3´ 0.3 mm2 (H´V) (Focused)

 

9.     Applications

Catalysis

Materials science

Environmental science

Physics

Chemistry

Biology

Geoscience

Cultural heritage

 

10.  Contacts

Name: Lihua Wang

Email: lhwang@sinap.ac.cn

    Phone: +86-21-33932079