Status, Progress and Outlook from AMOS Team Nora Berrah, WMU

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Status, Progress and Outlook from AMOS TeamNora
Berrah, WMU

• Team Organization.
• 2. Scientific Plan.
• Progress in Experimental Plan to Carry Out the
  First Experiment.
• 4. Future Plan.

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AMOP Collaborative Team ( Original Merged LOIs
A) Mariage of Synchrotrons Ultrafast Communities
Lou DiMauro (OSU) (T. Leader) Nora Berrah (WMU)
(co-T. Leader) John
Bozek (Instrument Scientist) Pierre Agostini
OSU Musahid Ahmed LBL John Bozek LBL Philip H.
Bucksbauom UM Roy Clarke UM Todd Ditmire UT
Austin Paul Fuoss ANL Ernie Glover LBL Chris
Greene U Colorado Elliot Kantor ANL Bertold
Kraessig ANL Steve Leone UC Berkeley Dan Neumark
UC Berkeley Gerhard Paulus Texas AM Steve Pratt
ANL Alexei Sokolov Texas AM John Reading Texas
AM David Reis UM Steve Southworth ANL Linn Van
Woerkom OSU Linda Young ANL
Twenty Additional Scientists Expressed Interest
at the October 2004 Workshop
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Update on AMOS Activities/ Organization

• Instrument Scientist on Board (Jan 2006)
• Weekly Teleconf (DiMauro, Bozek, Young,
  Bucksbaum, Berrah)
• N. Berrah on Sabbatical FY06
• Periodic visits by L. DiMauro
• 5. Communication with Broader Team at Conferences
  (Wisconsin W. 8/04 DOE M. 9/05 DAMOP 5/06)
• 6. E-mail Updates to Broader Team when Necessary
  (seek input, communicate news)

Discussions/communication led to determine the
instrumentation needs for first experiments!
7. Conceptual Design and Instrument Budget
was submitted and Accepted by LCLS.
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Outlook on AMOS Activities/ Organization (Cont..)

• 8. Synergy between the PULSE Center and AMOS
• 9. Workshop to Stimulate Theory (ITAMP 06-06)
• 10. Met with
• -----LCLS Optics Group
• ------Pump-Probe Team to Explore
  Common Interest and will Continue
  to Meet.
• 11. Plan to Meet with Imaging Group to Explore
  Shared Experimental System?
• 12. Organize LCLS/PULSE Summer School June 2007

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• AMOS Major Scientific Thrusts
• X-Ray Strong Field Physics
• Dynamics at the Atomic- Scale
• Fundamental Atomic and Chemical Physics

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Status of Broad Scientific Plan

• High Field Studies in Atomic, Molecular, Cluster,
  Ion and Biological Systems.
• -- Apply x-ray nonlinear processes to
  characterize the LCLS x-ray pulse
• 2. Time-resolved Studies of Molecules and
  Clusters
• 3. Scattering Experiments of Molecules and
  Clusters

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Initial Scientific Goals (First 2 Years)

• High Field Studies in Atoms (Ne) in Molecules
  (HBr) and in van der Waals Clusters and C60.
• Two-Color Auger Sideband Experiment (initial
  timing diagnostic)
• 3. High Field Studies in Ions(Ne8,Fe, C60/-,
  S-)
• 4. Scattering Experiment on Laser Aligned
  Molecules

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Introduction/Background

• Although the Weak Field Regime with Synchrotrons
  Provides Inner-Shell Photoionization Baseline
  Data for Atoms, Molecules, Clusters and their
  ions
• And
• Laser High Field Research is Better Understood
• AMO Research with LCLS is a New Ball Game!

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Because

• The LCLS beam intensity (1013 x-rays/200 fs) is
  greater than the current 3rd generation sources
  (104 x-rays/100 ps).
• Extreme focusing leads to intensity 1035
  photons/s/cm2 ( 1020 W/cm2 for 800 eV x- rays)
• Nonlinear and strong-field effects are expected
  when the LCLS beam is focused to a spot diameter
  of 1µm.
• BUT, electrons ponderomotive (quiver motion)
  important at low frequencies IS negligible in the
  x-ray regime (?2).

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Low-Frequency Physics ? High Frequency
IR Low frequency regime
VUV FEL Intense photon source
XFEL FEL Highly ionizing source

• Keldysh parameter ? gtgt1
• Multi-photon ionisation
• Ponderomotive energy 10 meV

• Angstrom wavelength
• Direct multiphoton ionisation
• Secondary processes

• Keldysh parameter ? ltlt1
• Tunnel / over the barrier ionisation
• Ponderomotive energy 10 100 eV

? ? Optical Frequency (Ip/2Up)1/2
???-1 UpI/4?2 (au) Tunneling
Frequency
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LCLS Beam will Allow Investigation of

• Multi-photon excitation/ionization ? Highly
  excited states of matter Multiple ionization
  sufficiently rapid to form hollow atoms
  Multiply-charged targets allows absorption below
  the edge
• Collective tunneling effects?
• Rescattering of ionized electrons with the
  targets?
• Certainly new and unexpected phenomena!!

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How Would LCLS High Field Affect

• Auger Processes Subsequent to Inner-Shell
  Photoionization of Gas-Phase Matter? Nonlinear
  effects, Multiple core hole formation (Ne, S-)
• Inner-Shell Resonances (excitation to Rydberg
  state, doubly or triply excited states)? (Ar, CO,
  HBr)
• Threshold Effects? PCI (Ar) Electron Recapture?
  (Li-)
• 4. Fragmentation dynamics? (OCS, Van der Waals
  Clusters)

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LCLS High Field Beam will Favor Non-Sequential
Auger Decay
Sequential(or Cascade) Multi-Auger Decay
Photodetachment (or Ionization)
SimultaneousDouble-Auger Decay (? 3-10 of
single Auger)
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Double K Vacancy in Gas-Phase Systems Possible
Consequences

• The decay of the KK-vacancy state will produce
  higher charge states
• This process ? extensive fragmentation in
  molecules
• This process ? damage consideration in
  experiments on Bio-molecules?

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High Field Studies in Atoms
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FLASH Experiment
PRL 94, 023001 (2005)
Theory Available! Calculate the rate of
production of highly charged Xei ions produced
by direct multiphoton absorption, to compare with
experiment.
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TOF Spectrum for Atomic Xenon Multiphoton
Ionization (Wabnitz et al.05 )
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Wabnitz et al. 05
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First LCLS Experiment K-Shell in Ne1.
Photoionization2. Auger Decay3. Sequential
Multiphoton Ionization4. Direct Multiphoton
Ionization TheoryDouble-K ionization in Ne
due to absorption of 2-photons by 1 atom for
h?gt932 eV is predicted to be 100
LCLS
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2 e-out
The probability of two-photon absorption by 1s2
-shell accompanied by the creation of double
1s-vacancies predominates over the probability of
the process of two-photon one-electron
excitation/ionization of the 1s2 shell in the
range of x-ray photon energies 930 eV.
1e-out
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Inner-Shell Resonances in Ar 2 p Excitation to
Rydberg States(ALS)
LCLS K-Shell Ar How would the ratio of Doubly
Ionized Ions (Auger decay) Compares to Singly
Ionized Ions due to spectator Auger decay?
Resonant shake-off of two electrons.
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High Field Studies in Molecules
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Molecular Fragmentation Ion Momentum Imaging of
Molecules (ALS)
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Resonant Auger Electron Spectroscopy

• Interesting in molecules too CO resonant Auger

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Probe Auger(2)/Spectator Auger(1) Decay
Fragmentation Pathways
Spectator Auger
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HBr 3d (ALS) Excitation/Ionization 2D Map
Angle-Resolvede- TOFs
LCLS HBr 2p 2s Ionization
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High Field Studies in Clusters
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Cluster Studies at FLASH in Hamburg
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Cluster Studies, FLASH
Xenon Cluster size 2500 atoms
Tpuls50 fs lFEL98 nm

• Unusually high energy absorption in cluster
• Fragmentation starting at 1011 W/cm2

Wabnitz et al, Nature 420, 482 (2002)
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Coulomb explosions change at short wavelengths
Source Wabnitz et al, Nature, Dec 2002
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Molecular dynamics simulations indicate that
standard collisional heating cannot fully account
for the strong energy absorption.
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LCLS Ion, e-, and Scattering Experiments on
Clusters

• Study the Dynamics of Cluster Explosion as a
  Function of Cluster Size, Wavelengths, Intensity
• Is it a Coulomb Explosion Picture (as in
  intense optical or near IR ultrafast laser
  pulses) OR
• Explosion due to Hot Nanoplasma (multiple
  scattering from the cluster atoms can confine
  electrons yielding a nanoplasma) Explosion Time
  can be Different
• OR, New mechanisms??
• Will Collective Electron Effects be important as
  in the dynamics of IR irradiated large clusters?

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Two Dimensional Map of Xe Clusters for 4d
Ionization (ALS)
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Size Effect Revealed via Angle-Resolved Study of
Xe Clusters (ALS)
___ Atomic data
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High Field Studies in Ions
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High Charge State Formation Following 2p
Photodetachment of S- (ALS)
S2/S? 60
Li3/Li2lt1
Th, Sim-Auger
Int, K-Out
H, S-Off or S-UpSeq-Aug
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Where will the Action Take Place?
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AMO home?

• Instrument Layout Primarily on Side-Branch

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AMO Instrument - Layout

• Use APS style tables with multiple axes of motion

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AMO Instrument - Layout

• Instrument control issues
• Many stepper motors (50-100) to align chambers,
  position detectors, etc
• High voltage (dozens) controlled through 0-10V
  analog signals (and similarly monitored)
• Valves pumps etc for vacuum system
• Valves pumps for gas handling system
• Hoping whole control system architecture can live
  in hutch (no long cable pulls)

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How do We Plan to Carry Out the First Experiments?
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Two Classes of Experiments

• Kinematic Complete Characterization (e-, Ion,
  Photon)
• --- High/low resolution
  instrumentations
• Multiple e- and Ions Imaging Detectors (5
  e- TOFs, COLTRIMs, Fluorescence
  Detectors).
• ----Dilute species/single shot
  measurements
• 2. Photon-In/Photon-Out (Diffraction)

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High Field Experiments Fluorescence Spectrometers

• Probe entirely different electronic channels than
  those available to electronic transitions
• Much less sensitive to space-charge broadening

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Schematic of the High-Field Experimental System
Being made by John
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High Field Experiments e--Ions Detection

• Use 5 e- time-of-flight spectrometers to measure
  energy and angular distributions of electrons
• Choose geometry to obtain appropriate information
• KE of electron will reveal multi-photon
  absorption
• Signature of multiple photon excitation/ionization
  usual selection rules broken
• Different l-values accessible (instead of ?l
  1, -1 get ? l -2, 0, 2) i.e. s-to-s and
  s-to-d transitions accessible
• Dipole angular distributions (i.e. ß -1, 0, 2)

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Details AMOS Three type of Detectors

• 2D X-ray detector to be used for small-angle
  elastic scattering (same as Imaging Group).
• . Electron detectors, 5 time-of-Flights, 50 ps
  time resolution, 50 mm diameter, 120 Hz readout
  time Electron energy angular distributions

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Detail Ion Detectors (continued)

• Ion detector for momentum measurement, Energy
  resolution better than 5µeV (with a supersonic
  beam. Spatial resolution better than 50µm (we
  expect 20µm). Temporal resolution better than
  100ps (we expect 50 ps). Detector area 80 mm or
  120 mm diameter, multihit capability 3 events /
  50 nsec (30 events / 50 nsec in future)

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LCLS AMO Project Timeline

• Design begins June 2006
• completed August 2007
• Purchasing initiated in FY07
• Assembly testing in FY08
• Staggered diagnostics, high field experiment,
  refocus optics, single particle diffraction
• Comissioning begins Nov 2008
• Full operation by project completion Mar. 2009

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Beyond the First Experiments

• 1. Probing metal clusters photoionization-produce
  d charge states, as a function of time, photon
  energy, intensity, cluster size.
• 2. Probing inner-shell relaxation in real time,
  in an atom or a simple molecule Study timescale
  of the fragmentation via pump-probe techniques
• Chirped multiphoton excitation to excite an
  entire atomic shell to a higher shell, in a
  single pulse (Ultimate Goal Precise Control and
  Charaterization of X-Ray Fields).

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Advantages of AMO for Single Particle
Imaging/Diffraction

• Structure of size-selected clusters (when
  combined with ion beamline to create monodisperse
  beam)
• Dynamic imaging of dissociating molecules,
  exploding clusters, etc
• Cost of detectors encourages purpose built
  chamber to be shared??

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Further Equipments needs

• Lower photon energies beamline (C edge)
• Monochromator for low hv (below 800 eV)
• Laser ablation system to generate metal clusters
• Ion source (ECR/EBIT?)
• He cryostat for cluster source (including metal
  clusters).
• Streak camera

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RD Needs

• KB focusing pair (submicron spot size, for soft
  x-rays)
• Imaging of fast (keV) electrons
• High readout rate detectors.
• Improved Synchronization between laser and LCLS
  pulse (pump-probe)
• Non-collinear/collinear X-ray delay line
• X- ray Interferometers development (3-10)
• Support to Theorists for modeling and predictions

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END