Status, Progress and Outlook from AMOS Team

Nora Berrah, WMU

1. Team Organization.

2. Scientific Plan.

3. Progress in Experimental Plan to Carry Out the First Experiment.

4. Future Plan.

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 LBLJohn Bozek LBL Philip H. Bucksbauom UMRoy Clarke UM Todd Ditmire UT AustinPaul Fuoss ANL Ernie Glover LBLChris Greene U Colorado Elliot Kantor ANLBertold Kraessig ANL Steve Leone UC BerkeleyDan Neumark UC Berkeley Gerhard Paulus Texas A&MSteve Pratt ANL Alexei Sokolov Texas A&MJohn Reading Texas A&M David Reis UMSteve Southworth ANL Linn Van Woerkom OSULinda Young ANL

~ Twenty Additional Scientists Expressed Interest at the October 2004 Workshop

Update on AMOS Activities/ Organization

1. Instrument Scientist on Board (Jan 2006)2. Weekly Teleconf (DiMauro, Bozek, Young, Bucksbaum, Berrah)

3. N. Berrah on Sabbatical FY06 4. Periodic visits by L. DiMauro5. 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.

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

AMOS Major Scientific Thrusts:

•X-Ray Strong Field Physics •Dynamics at the Atomic- Scale

• Fundamental Atomic and Chemical Physics

Status of Broad Scientific Plan

1. 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

Initial Scientific Goals (First 2 Years)

1. High Field Studies in Atoms (Ne) in Molecules (HBr) and in van der Waals Clusters and C60.

2. 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

• 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!

Introduction/Background

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, electron’s ponderomotive (quiver motion) important at low frequencies IS negligible in the x-ray regime (λ2).

Low-Frequency Physics → High Frequency

- Ip

1015 W/cm2

- Ip

1013 W/cm2

- Ip10x20 W/cm2

• Keldysh parameter <<1• Tunnel / over the barrier

ionisation• Ponderomotive energy 10

– 100 eV

• Keldysh parameter >>1

• Multi-photon ionisation• Ponderomotive energy 10

meV

IR:Low frequency regime

VUV FEL:Intense photon source

XFEL FEL:Highly ionizing source

• Angstrom wavelength• Direct multiphoton ionisation• Secondary processes

Optical Frequency = (Ip/2Up)1/2 -1; Up=I/4ω2 (au) Tunneling Frequency

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!!

How Would LCLS High Field Affect:

1. Auger Processes Subsequent to Inner-Shell Photoionization of Gas-Phase Matter? Nonlinear effects, Multiple core hole formation (Ne, S-)

2. Inner-Shell Resonances (excitation to Rydberg state, doubly or triply excited states)? (Ar, CO, HBr)

3. Threshold Effects? PCI (Ar) Electron Recapture? (Li-)

4. Fragmentation dynamics? (OCS, Van der Waals Clusters)

LCLS High Field Beam will Favor Non-Sequential Auger Decay

Photodetachment(or Ionization)

Auger Decay

Sequential(or “Cascade”)

Multi-Auger DecayAuger Decay

SimultaneousDouble-Auger Decay( 3-10% of single Auger)

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?

High Field Studies in Atoms

Theory Available! Calculate the rate of production of highly charged Xei+ ions produced by direct multiphoton absorption, to compare with experiment.

PRL 94, 023001 (2005)

FLASH Experiment

TOF Spectrum for Atomic Xenon Multiphoton Ionization (Wabnitz et al.’05 )

Wabnitz et al. ‘05

First LCLS Experiment: K-Shell in Ne

1. Photoionization2. Auger Decay3. Sequential Multiphoton Ionization4. Direct Multiphoton Ionization

Theory:Double-K ionization in Ne due to absorption of 2-photons by 1 atom for hγ>932 eV is predicted to be 100%

LCLS

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.

2 e-out

1e-out

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.

High Field Studies in Molecules

Molecular Fragmentation: Ion Momentum Imaging of Molecules (ALS)

Resonant Auger Electron Spectroscopy

• Interesting in molecules too – CO resonant Auger:

Probe Auger(2+)/Spectator Auger(1+) Decay & Fragmentation Pathways

Spectator Auger

LCLS: HBr

2p & 2s Ionization

HBr 3d (ALS) Excitation/Ionization

2D Map; Angle-Resolved;e- TOFs

High Field Studies in Clusters

Cluster Studies at FLASH in Hamburg

Cluster Studies, FLASH

200 400 600 800

2*1010

Xe+

8*1010

Inte

nsity (

arb

. u

nits)

Time of flight (ns)

6*1011

Xe2+

6*1012

3

54

PFEL

=2.5*1013

W/cm2

876

Tpuls=50 fs FEL=98 nm

Unusually high energy absorption in cluster

Fragmentation starting at 1011 W/cm2

Wabnitz et al, Nature 420, 482 (2002)

Xenon Cluster size 2500 atoms

Coulomb explosions change at short wavelengths

Source:Wabnitz et al,Nature, Dec 2002

Molecular dynamics simulations indicatethat standard collisional heating cannot fully account for the strong energy absorption.

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) ORExplosion 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?

Two Dimensional Map of Xe Clusters for 4d Ionization (ALS)

Size Effect Revealed via Angle-Resolved Study of Xe Clusters (ALS)

___ Atomic data

High Field Studies in Ions

High Charge State Formation Following 2p Photodetachment of S- (ALS)

Li3+/Li2+<1%

S2+/S+ 60%

Th, Sim-Auger

Int, K-Out

H, S-Off; or

S-Up+Seq-Aug

Where will the Action Take Place?

AMO “home”?• Instrument

Layout Primarily on Side-Branch

AMO Instrument - Layout• Use APS style tables with multiple axes of motion

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)

How do We Plan to Carry Out the First Experiments?

Two Classes of Experiments

1. 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)

High Field Experiments: Fluorescence Spectrometers

– Probe entirely different electronic channels than those available to electronic transitions

– Much less sensitive to space-charge broadening

Schematic of the High-Field Experimental System

Being made by John

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 Δl = +1, -1 get Δ l = -2, 0, +2) – i.e. s-to-s and s-to-d transitions accessible

– Dipole angular distributions (i.e. β = -1, 0, 2)

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

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)

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

1. Probing metal clusters photoionization-produced 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

3. 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).

Beyond the First Experiments

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??

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

R&D 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

END