Soft X-ray Lensless Imaging and Resonant Imaging Endstation · study of phase transitions –...

Soft X-ray Lensless Imaging and

Resonant Imaging Endstation Andreas Scherz (SIMES/SLAC)

3/2/2009 2LCLS/SSRL Users' Meeting 2008

Outline

study of phase transitions – single shot experimentsstudy of ultrafast electronic and spin dynamics –pump-probe experiments

soft x-ray resonant imaging endstation (low fluence)plans for high fluence or single shot experiments


Solid state and its excitations

E. Beaurepaire, et al.,PRL

76, p4250 (1996)

•Electron-Lattice Dynamics•Magnetization Dynamics


X-rays see them all

1fs-1ps


Soft X-ray Fourier Transform Holography

S. Eisebitt, J. Lüning, W. F. Schlotter, M. Lörgen, O. Hellwig, W. Eberhardt, J. Stöhr, Nature 432, 885 (2004)


Absorption Hologram

absorption

phase


Phase Hologram

absorption

phase

absorption reducedby order of magnitudefor comparable image

quality


Optical Constants

A. Scherz, et al., submitted.

Co L3

n = 1 ¡ ± + i¯Refractive Index

E (eV)776.5 779.5

Re( T )

Im( T )t = 1 ¡ ¹ + iÁweak contrast


frompump – probe where

time resolution is essentialto

imaging of critical fluctuations wherenumber of photons is essential

3/2/2009 10LCLS/SSRL Users' Meeting 20082D Ising model

T=TC

M=M

0

Â = 1kT

Pr ±¾r ±¾0

FMFM PMPM

TC =RT

Cu/Co/Cu(1 1 17)

single shotsingle shotat instant of timeat instant of time

5 μm 2.5 ML Co

FM - PM phase transition


critical opalescencereal space

reciprocal space


Dynamics of Critical Fluctuations

¿(Tc )¿o

=³

»(Tc )»o

´ z= 2

»(Tc) » 0.1 ¹ m

¿(Tc) » 80 ¹ s

(T ¡ Tc)=Tc ¼ 10¡ 3

2D Ising Model real spacereciprocal space


Requirements / Limits for imaging fluctuations

imaging magnetic fluctuations – need the full pulse intensityno “movie” possible, since the pulse drives the system out of equilibriumXPCS may then be possible using (cw) source with average high brightness


Correlated Materials


NEW PHASE DIAGRAM

OLD PHASE DIAGRAM

S. Kivelson,Nature materials (News and Views) 5,343 (2006)

Electronic liquid crystal:S.A.Kivelson et al, Nature 393, 550 (1998)

High-Tc superconductor


BL13-3 Coherent X-ray Scattering

a. Cryostat and sample holderb. in-vacuum CCD on linear stagec. Guard Apertures and magnetd. Coherence apertures / filters

Sample Environment

Soft X-ray coherent Scatteringresonant, polarization dependentX-ray Holography, MAD ImagingX-ray Photon Correlation Spectroscopy

Specs:Energy range 200-1200 eVCCD N.A. = 0.031 - 0.545max. q at 800eV: 2.3 nm-1

30nm resolution demonstrated at cryogenic temperatures

Covers important K and L edges forPolymers, Magnetic Nanostructures, Correlated Materials, Nanocrystals, Biominerals

Experiments

superparamagnetic array of 18nm Fe/FeO nanocubes

T= 15K

resolution ~30nm

SEM

1um

FTH


Layout

15-350K

.1 T


CCD Detector

Commercial CCD13.5um pixel size2048x2048 pixels2MHz pixel readout

for 850eV (1.46nm)1.7nm image pixel size @ 30mm18.5nm image pixel size @ 350mm

extras1um Al cover (optical filter)movable beamstop

PI-MTE


Radiation Damage

unfocused KB system<10uJ/cm2

focused KB system>10uJ/cm2

reflecting beamstop


Timeline

system using unfocused LCLS beam ready in July ‘09testing at BL 13, SSRL before summer shutdown


The End

Soft X-ray Lensless Imaging and Resonant Imaging Endstation · study of phase transitions –...

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