Coherent Imaging using X-ray FELs

Ivan Vartaniants HASYLAB at DESY, Hamburg, Germany Revolution in X-ray is just happening Revolution in X-ray Physics is just happening

April 2009

FEL x-rays at 1.5 Å on a YAG screen 50 m FEL power gain length measurement after the last inserted undulator (red points) at 1.5 Å made

P. Emma, et al., http://www-ssrl.slac.stanford.edu/ lcls/commissioning/documents/th3pbi01.pdf Outline

1. Introduction

2. Coherent Scattering and Phase Retrieval

3. Coherent X-ray scattering and Imaging in Material Science

• Present status

• Future applications

4. Requirements for Coherent X-ray scattering beamline at XFEL

5. Summary and Outlook

Ivan Vartaniants | MID Workshop Grenoble 28-29 October 2009 | Page 4 Coherent Scattering and

Phase Retrieval

Ivan Vartaniants | MID Workshop Grenoble 28-29 October 2009 | Page 5 Coherent imaging at FEL sources Iterative phase retrieval algorithm

FFT sk(x) Ak(q)

Real Space Constraints Reciprocal Space Constraints

s' (x) A' (q) k FFT-1 k

Real space constraints: Reciprocal space constraint: use all a priori knowledge: k q → exp q )(I)(A •finite support •positivity R.W.Gerchberg & W.O. Saxton, Optic (1972) 35, 237 •… J.R. Fienup, Appl Opt. (1982) 21, 2758 V. Elser, J. Opt. Soc. Am. A (2003) 20, 40 CXDI in practice is working well but

CXDI is a hungry technique

We can benefit from the use of ultrabright pulses of XFEL

Ivan Vartaniants | MID Workshop Grenoble 28-29 October 2009 | Page 8 The European X-Ray Project XFEL CXDI Experiments at XFEL

Coherent X-ray scattering and lensless imaging in

9 I. Vartaniants J. Rad. (2007). 14, 453–470 The European X-Ray Laser Project XFEL Coherent x-ray scattering and lensless imaging in materials science

Scientific aims ● 3D nanoscale structural analysis using CXDI technique ● main techniques proposed ⇒ Bragg diffraction for crystalline samples ⇒ Forward scattering for non-crystalline objects ● applications and systems of interest ⇒ Nanomaterials – properties of single particles (100×100×100 nm3 in single-shot) – quantum dots – anisotropic strain distribution of single islands (on surface or buried) ⇒ Mesoscale systems – obtain information about local properties of bulk structures avoiding averaging – metals (e.g. dislocations, nucleations) or ceramics (e.g. grain dynamics) ⇒ Dynamic processes/fluctuations – crystal surface morphology as function of time – spontaneous nucleation of clusters – crystalline fluctuations in disordered matter ⇒ Materials properties during processing – precipitates/pores growth or shrinkage – welding – laser ablation 10 I. Vartaniants J. Synchrotron Rad. (2007). 14, 453–470 The European X-Ray Laser Project XFEL Nanomaterials

107 106 105 104 103

102 (ph/sec) 101 elast I 100 10-1 10-2 0 50 100 150 200 250 300 Crystal size (μm) Elastically scattered intensity 11 2 incoming flux I0=10 ph/s·mm , E=20 keV 11 I. Vartaniants The European X-Ray Laser Project XFEL Nanomaterials

(c) 200 nm

0.08 Coherent GISAXS scattering 0.06 XFEL

-1 6 0.04

, Å 10 islands illuminated z q pushing the limits to 10 nm and below

0.02

0.00 -0.04 -0.02 0.00 0.02 0.04

q , Å-1 y 12 I. Vartaniants The European X-Ray Laser Project XFEL Coherent GISAXS Measurements (a) 50 nm (b) 140 nm

0.08

0.12

0.10 0.06

0.08 -1 -1

0.04 , Å z

, Å q z 0.06 q

0.04

0.02

0.02

0.00 0.00 -0.06 -0.04 -0.02 0.00 0.02 0.04 0.06 -0.04 -0.02 0.00 0.02 0.04 q , Å -1 -1 y q , Å (c) y 200 nm (d) 1000nm 0.08 0.05

0.04 0.06

0.03 -1 -1 0.0