Workshop on "X-ray Science with Coherent Radiation"

X-ray Coherence

2003

August 22-23

Satellite Meeting of SRI'03

Berkeley

California


International Workshop on

X-ray Science with Coherent Radiation



-- Satellite Meeting of SRI 2003

August 22-23, 2003
Building 50 Auditorium

Lawrence Berkeley National Laboratory

1 Cyclotron Road, Berkeley, CA 94720, USA

Workshop Chairs

Qun Shen (CHESS, Cornell)

John Spence (Arizona State/LBNL)
John Arthur (SSRL, Stanford)



International Committee

Donald Bilderback (Cornell)

Steve Dierker (BNL)
Sol Gruner (Cornell)
Tetsuya Ishikawa (SPring-8)
Janos Kirz (SUNY, Stony Brook)
Bruno Lengeler (Aachen)
Andreas Magerl (Erlangen)
Gerhard Materlik (Diamond)
Ian McNulty (APS)
Keith Nugent (Melbourne)
Howard Padmore (ALS)
Jean Susini (ESRF)
Mark Sutton (McGill)
Edgar Weckert (Hasylab)
Local Coordinators

Virginia Bizzell (CHESS, Cornell)

Cathy Cooper (LBNL)
Laura Brown (CHESS, Cornell)
Financial Support

by US National Science Foundation

through

CHESS, Cornell University

and

by US Department of Energy

through

Lawrence Berkeley National Lab

Argonne National Lab

Workshop Proceedings: http://erl.chess.cornell.edu/

Cover: View from Cyclotron Road. Photograph provided by Lawrence Berkeley National Lab.



Table of Contents

Workshop Program .................................................................................................................. 4

Friday, August 22 ............................................................................................................... 4

Saturday, August 23 .......................................................................................................... 5

Invited Talk Abstracts ............................................................................................................. 6

Energy recovery linac source properties ........................................................................... 7

Linac based X-ray sources: temporal & spatial coherence ............................................... 7

Tutorial: Coherence in X-ray physics ................................................................................ 8

X-ray intensity correlation spectroscopy ........................................................................... 8

Dynamic SAXS with coherent x-rays ................................................................................ 8

Soft x-ray coherent magnetic scattering experiments ....................................................... 9

Inversion of coherent diffraction images of nanocrystals .................................................. 10

Ptychography and diffractive imaging with x-rays & electrons .......................................... 10

Coherence preserving reflecting and crystal optics .......................................................... 11

Shaping x-rays by diffractive coded nano-optics .............................................................. 12

X-ray coherence measurements ....................................................................................... 12

Nanometer imaging with high brightness source .............................................................. 13

Coherence and x-ray microscopy ..................................................................................... 15

Recovering phase and correlations from x-ray fields ........................................................ 16

3D phase tomography ...................................................................................................... 16

X-ray vortices in coherent wavefield ................................................................................. 17

Diffractive optics and shearing interferometry .................................................................. 18

Fourier transform holography ........................................................................................... 19

Two-photon interferometry ................................................................................................ 19

Diffraction Imaging of the general particle ........................................................................ 20

Diffraction imaging with coherent x-rays ........................................................................... 20

3D X-ray microscopy by phasing diffraction patterns ........................................................ 20

Hydrodynamic models of x-ray irradiated bio-molecules ................................................... 21

Poster Abstracts ...................................................................................................................... 22

Focusing X-ray Beams to Nanometer Dimensions ........................................................... 23

Magnetic Speckles from Nanostructures .......................................................................... 23

Single-Element Elliptical Hard X-Ray Micro-Optics .......................................................... 24

A fast CCD camera for x-ray photon correlation spectroscopy and

time-resolved x-ray scattering and imaging ................................................................ 24

Some Consequences of Focusing in Coherent Diffraction ............................................... 25

Lessons from an Experiment of High Resolution Fourier Transform

Holography with Coherent Soft X-rays ....................................................................... 25

Time-Resolved Phase Contrast Radiography and DEI with

Partial Coherent Hard X-Ray at BSRF ....................................................................... 26

Invalidity of low-pass filtering in atom-resolving x-ray holography ................................... 26

Table of Contents

Measurements of Spatial Coherence of X-ray Laser

from Recombining Al Plasma ..................................................................................... 27

Avoidance and Removal of Phase Vortices in Reconstruction

of Noisy Coherent X-ray Diffraction Patterns .............................................................. 27

Pushing the Limits of Coherent X-Ray Diffraction: Imaging

Single Sub-Micrometer Silver Nanocubes .................................................................. 28

Coherent Soft X-ray Branchline at the Advanced Light Source ........................................ 29

Near-diffraction limited coherent X-ray focusing using planar

refractive lenses made in epoxy resist SU8 ................................................................ 29

Quantum-Deceleration Self-Modulation of High Energy Electron Beam

and the Problem of Optimization of Coherent Photon Collider ................................... 30

Coherent hard x-ray scattering experiments at large diffraction angles ............................ 31

Multilayer X-Ray Optics: Progress in Coherence Preservation ......................................... 32

Attendees List ........................................................................................................................... 33

Program: Friday, 22 August, 2003

7:30 - 8:30 Continental breakfast, registration, poster set-up.
8:30	Qun Shen (Cornell)	Welcome
Session 1: New Sources and Tutorial
	Janos Kirz (SUNY-SB) - Chair
8:35	Sol Gruner (Cornell)	Energy recovery linac source properties
8:55	Jerry Hastings (Stanford)	Linac based X-ray sources: temporal & spatial coherence
9:15	Bruno Lengeler (Aachen)	Tutorial: Coherence in X-ray physics
10:05 Coffee Break and Poster Viewing (25 min.)
Session 2: Coherent Diffuse Scattering
	Sunil Sinha (UCSD) - Discussion Leader
10:30	Mark Sutton (McGill)	X-ray intensity correlation spectroscopy
11:00	Gerhard Grübel (ESRF)	Dynamic SAXS with coherent x-rays
11:30	Jeroen Goedkoop (Amsterdam)	Soft x-ray coherent magnetic scattering experiments
12:00	Discussion on coherent diffuse scattering
12:15 Lunch: no-host (LBNL cafeteria), and Poster Viewing

Session 3: Coherent Diffraction on Nanocrystals
	Steve Wilkins (CSIRO) - Discussion Leader
14:00	Ian Robinson (UIUC)	Inversion of coherent diffraction images of nanocrystals
14:30	John Spence (ASU)	Ptychography and diffractive imaging with x-rays & electrons
15:00	Discussion on coherent diffraction on nanocrystals
15:15 Coffee Break and Poster Viewing (25 min.)
Session 4: X-ray Optics for Coherence
	Don Bilderback (Cornell) - Discussion Leader
15:40	Tetsuya Ishikawa (SPring8)		Coherence preserving reflecting and crystal optics
16:10	Enzo Di Fabrizio (Eletra)		Shaping x-rays by diffractive coded nano-optics
16:40	David Paterson (APS)		X-ray coherence measurements
17:00	Wenbing Yun (Xradia)		Nanometer imaging with high brightness source
17:20	Discussion on x-ray optics for coherence
17:35 Adjourn for the day

Program: Saturday, 23 August, 2003

7:30 - 8:20 Continental breakfast.
Session 5: Phase Contrast Microscopy
	Ian McNulty (APS) - Discussion Leader
8:20	Chris Jacobsen (SUNY-SB)	Coherence and x-ray microscopy
8:50	Keith Nugent (Melbourne)	Recovering phase and correlations from x-ray fields
9:20	Peter Cloetens (ESRF)	3D phase tomography
9:50	Andrew Peele (Melbourne)	X-ray vortices in coherent wavefield
10:10	Discussion on phase contrast microscopy
10:25 Coffee Break and Poster Viewing (20 min.)
Session 6: Holography and Interferometry
	Ken Finkelstein (Cornell) - Discussion Leader
10:45	Christian David (PSI)	Diffractive optics and shearing interferometry
11:15	Anatoly Snigirev (ESRF)	Fourier transform holography
11:45	Makina Yabashi (SPring8)	Two-photon interferometry
12:15	Discussion on holography and interferometry
12:30 Lunch: brown-bag (Bldg.50 Auditorium), and Poster Viewing

Session 7: Coherent Diffraction Imaging
	John Spence (ASU) - Discussion Leader
14:00	David Sayre (SUNY-SB)	Diffraction Imaging of the general particle
14:30	John Miao (Stanford)	Diffraction imaging with coherent x-rays
15:00 Coffee Break and Poster Viewing (20 min.)
15:20	Malcolm Howells (LBNL)	3D X-ray microscopy by phasing diffraction patterns
15:50	Stefan Hau-Riege (LLNL)	Hydrodynamic models of x-ray irradiated bio-molecules
16:10	Discussion on coherent diffraction imaging
16:25	John Arthur (Stanford)	Workshop summary
16:40 End of Workshop

Invited Talks

Invited Abstracts: Friday Morning

Energy Recovery Linac (ERL) Source Properties
Sol M. Gruner

Physics Dept. & Cornell High Energy Synchrotron Source (CHESS)

Cornell University, 162 Clark Hall, Ithaca, NY 14853-2501
Energy Recovery Linacs are being explored as next generation synchrotron light sources. The fundamental x-ray beam properties from storage ring sources, such as the source size, brilliance, and pulse duration are limited by the dynamic equilibrium characteristic of the magnetic lattice that is the storage ring. Importantly, the characteristic equilibration time is long, involving thousands of orbits around the ring. Advances in laser-driven photoelectron sources allow the generation of electron bunches with superior properties for synchrotron radiation. ERLs preserve these properties by acceleration with a superconducting linac, followed by transport through a return loop hosting insertion devices, similar to that of a 3^rd generation storage ring. The loop returns bunches to the linac 180° out of accelerating phase for deceleration through the linac and disposal. Thus, the electron beam energy is recycled back into the linac RF field for acceleration of new bunches and the equilibrium degradation of bunches never occurs. The superior properties of ERLs beams include extraordinary brilliance and small source size, with concomitant high tranverse coherence, x-ray pulse durations down to ~100 femtoseconds, and flexibility of operation. The source properties will be discussed in terms of coherent applications.

Linear Accelerator Based X-Ray Sources: Temporal and Spatial Coherence
J. B. Hastings

SSRL

Stanford Linear Accelerator Center
Accelerator based synchrotron radiation (SR) sources are now commonplace in the world with the USA (APS), Japan (Spring-8) and Europe (ESRF) each operating storage ring sources in the hard x-ray energy range that provide unique radiation for studies in the chemical, biological and materials sciences. These sources are critical to the understanding of complex static structures and through inelastic x-ray scattering the dynamics. They have also been applied to time resolved diffraction on the scale of the photon pulse length ~100 psec. Photon beams with all the properties of SR but with pulse lengths of ~100 fsec are now available from linear accelerator based sources, for example the Sub-Picosecond Pulse Source (SPPS) at the Stanford Linear Accelerator Center (SLAC). X-ray free electron lasers providing unprecedented pulse intensities, full transverse coherence, and pulse lengths of ~ 100 fsec. are operating in the 100nm wavelength range and are in various stages of planning to reach the 0.1 nm range. The FEL process and the unique properties of these sources will be discussed.
Invited Abstracts: Friday Morning

Tutorial: Coherence in X-ray Physics

B. Lengeler

Aachen University

The concept of coherence is used in quantum mechanics, optics, x-ray and neuron scattering, mesoscopic electron transport. It will first be discussed what interferes in a physical event and what destroys interference. Then we treat chaotic light sources and one-mode lasers and the description of that light in terms of coherence functions of first and second order. The influence of the sample on coherence will be treated in a third part. The uncertainty in the momentum transfer defines a generalized coherence volume. When its size is larger than the illuminated volume speckle can be observed. Differences in x-ray, neutron and electron transport will be addressed. A few examples will illustrate the concepts.

X-ray Intensity Fluctuation Spectroscopy
Mark Sutton

McGill University

Intensity fluctuation spectroscopy (IFS) is an ideal way to study the kinetics of fluctuations in a system provided that the scattering intensity is sufficient for the time scales of the system under study. For the last three to four decades, it has been extensively used with light scattering to study a large variety of systems.  With the extension of the technique into the x-ray region, one has the advantage of accessing opaque materials, probing much shorter length scales and being less affected by multiple scattering. The prime disadvantage of x-rays over visible light is the much lower intensity levels of x-ray sources. This talk will summarize some of the recent results using the technique and then discuss current limitations with respect to new sources, new optics and new detector developments.

Dynamic Small Angle Scattering with Coherent X-Rays
G. Grübel

European Synchrotron Radiation Facility, BP 220, 38043 Grenoble, France

Complex relaxations in disordered systems have been studied successfully by scattering of both visible light and neutrons. Neutron based techniques can probe the dynamic properties of matter at high frequencies from  typically equal to 10¹⁴ Hz down to about 10⁷ Hz and achieve atomic resolution. Photon Correlation Spectroscopy (PCS) with visible light can cover low frequency dynamics (<10⁶ Hz), but probes only the long wavelength Q< 4*10^-3 Å^-1 region in materials not absorbing visible light. Coherent x-ray beams from third generation synchrotron radiation sources provide the possibility for correlation spectroscopy experiments with coherent x-rays (XPCS) capable of probing the low frequency dynamics (10⁶ Hz to 10^-3 Hz) in a Q range from 1^.10^-3 Å^-1 up to several Å^-1. XPCS can thus provide

Invited Abstracts: Friday Morning
atomic resolution, but has proven to be particularly powerful in the small angle scattering regime and for the study of complex fluids. XPCS can operate in optically opague materials and is not subject to multiple-scattering effects. We will review the status of XPCS in the SAXS regime by discussing the properties of static x-ray speckle as well as its applications for the study of dynamical phenomena in soft condensed matter systems (suspensions of colloidal particles, polymer micelles, surface dynamics on complex liquids).


Soft X-Ray Coherent Magnetic Scattering Experiments
J.B. Goedkoop, M.A. de Vries, J.F. Peters, J.Miguel

Van der Waals –Zeeman Institute

University of Amsterdam

Valckenierstraat 65, NL1018 XE Amsterdam

[e-mail]
N.B. Brookes, S.S. Dhesi

ESRF, B.P. 220, F-38034 Grenoble Cedex

The increased coherence of third generation synchrotron sources allows us to port laser techniques such as holography and dynamical light scattering from the visible to the x-ray spectral range. In addition to the obvious improvement in resolution, the x-ray range may allow for new variants that are not possible in the visible, as exemplified by techniques that use the strong magnetic contrast at soft x-ray resonances.

In this talk I will report on soft x-ray coherent magnetic scattering experiments performed on stripe magnetic domain systems as occurring in amorphous GdFe thin films with perpendicular anisotropy. This system was chosen in order to have maximum magnetic contrast, negligible charge scattering and minor multiple scattering.

These experiments were performed at the ESRF on a spectroscopy beam line using a phosphor screen + visible CCD detector. A careful Kramers Kronig analysis of the magnetic cross section was made at both the Gd M₅ and the Fe L₃ resonances, which matches experimentally observed scattering cross sections remarkably well and is in agreement with atomic calculations.

Despite non-ideal conditions we were able to obtain very high resolution speckle patterns both of ordered and disordered stripe systems from which the local magnetic correlation function can be obtained straightforwardly. Attempts at speckle inversion of these data have been foiled by lack of q-range.

Invited Abstracts: Friday Afternoon
We will discuss the field and energy dependence of the speckle patterns. We show that the scattered intensity in our experiment do not show energy-dependent anomalous interference between the magnetic and charge scattering contributions.

Finally, first attempts at critical scattering at the Gd M₅ edge of epitaxial Gd (0001) layers on W are reported. Despite mK temperature resolution and stability no such scattering could be observed, explainable by sample imperfections, lack of sufficient flux and detector insensitivity.

Inversion of Coherent Diffraction Images of Nanocrystals
Ian Robinson

University of Illinois, Urbana, IL.

In this talk, I will present the progress we have made towards reconstruction of real space images by inversion of coherent X-ray diffraction from small crystals. We have found that iterative Fourier transform methods based on the Fienup/Gerchberg/Saxton method can be successful under some circumstances. These methods work because the diffraction pattern can be oversampled with respect to the spatial Nyquist frequency. A strong real-space constraint in the form of a "support" region surrounding the object appears to be sufficient, but some anti-stagnation strategy is also necessary. The resulting images of gold nanocrystals are interesting in that internal striations are present [1]. The striations probably arise because of stresses present during the growth of the crystals. I will discuss the merits of possible enhancements to the technique enabled by the introduction of focusing optics in front of the sample.
[1] "Three-dimensional Imaging of Microstructure in Gold Nanocrystals", G. J. Williams, M. A. Pfeifer, I. A. Vartanyants and I. K. Robinson, Physical Review Letters 90, 175501-1 (2003).


Ptychography and Coherent Diffractive Imaging - X-rays and Electrons

John Spence

Arizona State Univerisyt, Physics, and LBNL

[e-mail]

    Several ideas, developed over half a century, have now converged to provide a working solution to the non-crystallographic phase problem. These include Sayre's 1952 observation that Bragg diffraction undersamples diffracted intensity relative to Shannon's theorem, that iterative ("HiO") algorithms with feedback rarely stagnate (Gerchberg-Saxton-Feinup), producing an astonishingly successful optimization method, and that these iterations are Bregman Projections in Hilbert space. Modern algorithms based on these ideas have recently produced the first spectacular atomic-resolution image of a double-walled nanotube

Invited Abstracts: Friday Afternoon
from experimental electron diffraction patterns (Zuo et al, Science, 300, 1419 (2003) ), and lensless X-ray images at 20nm resolution (Miao et al Nature, 400, p. 342 (199), He et al Phys Rev B. 67, p. 174114 (2003) ). In this talk two new ideas will be presented. First, recent experimental application of the "Shrinkwrap" HiO algorithm (Marchesini et al, (2003) in press)  will be given. This algorithm inverts X-ray speckle patterns to images without knowledge of the object boundary. Experimental results are given with 20nm resolution. Secondly, the use of compact support along the beam direction in the transmission geometry for a thin diffracting slab will be described as a phasing method. Simulations for cryo-TEM tomography of protein monolayers shows that this use of the HiO algorithm greatly reduces the number of TEM images needed to provide known phases for the three-dimensional diffraction data (Spence et al, J.Struct Biol, in press, also  Weierstall et al, Ultramic 90, 171 (2001).  Finally, a conceptual connection between the HiO "oversampling" method (which requires diffracted intensity measurements at half the "Bragg" angle) and Ptychography (which uses interference between adjacent coherent diffraction orders) will be suggested.

Coherence Preserving Reflecting and Crystal Optics
Tetsuya Ishikawa

SPring-8/RIKEN

Kouto 1-1-1, Mikazuki-cho, Sayo-gun, Hyogo 679-5148; e-mail: [e-mail]
Perfect preservation of x-ray coherence requires x-ray mirrors with atomic scale smoothness. The SPring-8 is collaborating with the Osaka group for producing better x-ray mirror. Image profiles of the reflected x-ray beam with coherent illumination are well reproduced by combining a calculation based on numerical Fresnel-Kirchhof integration with surface figure data measured with micro-stitching interferometry. Since figuring methods developed by the Osaka group are numerically controllable, we can correct the surface figure to a limit posed by the metrology. An elliptical mirror gave a nearly diffraction-limited focus line of 200 nm width. Kirkpatric-Baes combination of two elliptical mirrors gave a point focus of 200×200 nm². After making some figure correction, the focal spot size was reduced to 90×180 nm². Up to now, we do not make any coating on mirror surface. If we can coat heavy metals to increase the numerical aperture without degrading the surface figure, the calculated focal size in ideal case will be down to 30×60 nm².

We have given an integral-form solution of time-dependent Takagi-Taupin equation for perfect crystal, and discussed propagation of coherence through dynamical x-ray diffraction. This has led to a simple method of measuring the modulus of mutual coherence function. One important conclusion is that we cannot always longitudinal and transverse coherence components. We will report the present status of synthetic diamond crystals in Japan and discuss some issues on diamond crystals in view of coherence preservation.

Invited Abstracts: Friday Afternoon