Background and Present Status from AMO Instrument

Team

1. Team Organization.

2. Proposed Scientific Plan.

3. The First Experiment.

4. Future Plan.

Historical Facts

• April 2004: LCLS puts out a call for Letters of Intent (LOI)category A: science & end-station constructioncategory B: sciencecategory C: instrument design

• July 2004: LCLS SAC makes recommendation that two AMO proposals of the “category A LOI” collaborative teams merge

• October 2004: Ultra-fast science workshop

October 2004: Ultra-fast science workshop

►Workshop Objective:solicit input & participation from the AMOP community for the LCLS project

- shape the scientific program: Scientists ideas

- help define the critical XFEL machine parameters

- help define the designs of an AMOP end-station(s)

- interaction of the five collaborative teams

► Five LCLS collaborative teams:- Atomic, Molecular & Optical Science

- Optical pump x-ray probe studies in chemistry, biology & material science

- Diffraction imaging of single objects approaching atomic scale resolution

- Coherent x-ray scattering for the study of dynamics

- High-energy density science

AMO Collaborative Team ( Original Merged LOIs A)Marriage of Synchrotrons + Ultrafast Communities

Lou DiMauro (OSU) & Nora Berrah (WMU) (co-T. Leaders)

John Bozek (Instrument Scientist)

Pierre Agostini OSU Musahid Ahmed LBLJohn Bozek LBL Philip H. Bucksbaum SU/SLACRoy 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 AMO Organization/Activities

1. Instrument Scientist, John Bozek, Hired (Jan 2006)2. Regular Teleconference (Berrah, Bozek, DiMauro, Young)

3. N. Berrah on Sabbatical FY06 4. Periodic visits by DiMauro/Berrah5. 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.

Update on AMO 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. Held Ultrafast x-ray Summer School June 2007

Team Major Scientific Thrusts:

•Multiphoton and High-Field X-Ray Processes in Atoms, Molecules, Clusters,& Biological Molecules.

•Time-Resolved Phenomena in Atoms, Molecules (bio-molecules) and Clusters using Ultrafast X-Rays

AMO LOIs Collaborative Team

Science:

1. Multiple core excitation in atoms, molecules and clusters

2. Timing experiments: Inner-shell side band experiments Photoionization of aligned molecules

Temporal evolution of state-prepared systems

3. Nonlinear physics

4. Ion (positive/negative) studies

5. Pump-probe, X-X or X-laser or X-e

6. Raman processes

7. Cluster dynamics (Diffraction of size-selected clusters)8. Photoionization dynamics of biomolecules

Ken Taylor (Ireland) Possibilities for few- and many-electron atoms & ions in XFEL pulses

David Reis (UM) Synchronization issues for pump-probe experiments at LCLS

Robin Santra (ITAMP) Cluster physics at high photon energies

Anders Nielsson (SSRL) Time resolved spectroscopy for studies in surface chemistry and electron driven processes in aqueous systems

Chris Greene (UCB) Multiphoton ionization processes in free atoms and clusters

John Bozek (ALS, LBNL) Atoms, molecules, clusters and their ions studied with two or more Photons

Ali Belkacem (LBNL) Inner-shell ionization and de-excitation pathways of laser-dressed atoms and molecules

Keith Nelson (MIT) Give him 10 minutes max and then let's get back to reality

Ernie Glover (LBNL) X-ray/optical wave mixing

Elliott Kanter (ANL) Hollow neon atoms

Science discussed at 2004 October AMOS forum

LCLS Characteristics

• The LCLS beam intensity (~1013 x-rays/200 fs) is greater than the current 3rd generation sources (104 x-rays/100 ps).

• Extreme focusing (KB pairs) 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).

AMOS Inst.Team Short-Long Range Plans:AMOS Inst.Team Short-Long Range Plans:

High Field: Using the extremely high brightness of the LCLS we propose to study:

→multiple ionization atoms & simple molecules with angle-resolved spectroscopy and ion imaging to understand basic phenomena in highly excited matter

→High-field photoionization in clusters (of various types)

→Low density ionic targets: atoms, molecules, fragments, clusters, biomolecules by photoelectron and ion imaging techniques

Time-Resolved: Temporal resolution will be used to perform:

→Inner-shell photoelectron spectroscopy of molecules (pump-probe using lasers) into specific states.

→Inner-shell photoelectron imaging of isolated biomolecules to follow their chemistry in natural time scale

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?

LCLS High Field Beam will Probe:

Photodetachment(or Ionization)

Auger Decay

Sequential(or “Cascade”)

Multi-Auger DecayAuger Decay

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

High Field Studies in Atoms

Some Examples

X-Ray Strong Field Experimentx-ray multiphoton ionization

photoionization

Auger

2-photon, 2-electron

sequential

correlated ionization

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

Intensity , Wavelength and Ponderomotive Energy (Lambropoulos)

λ (nm) ћω (eV) Up (eV) I (Up≈ ћω ) W/cm2

1242 1 1.27 7.8 1012

621 2 0.31 6.3 1013

310.5 4 7.9 10-2 5.0 1014

155.2 8 1.9 10-2 4.0 1015

77.6 16 4.9 10-3 3.2 1016

38.8 32 1.2 10-3 2.6 1017

19.4 64 3.1 10-4 2.1 1018

9.7 128 7.7 10-5 1.6 1019

4.9 256 1. 10-5 1.3 1020

2.4 512 4.8 10-6 1.1 1021

1.2 1024 1.2 10-6 8.4 10 21

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 Experiments

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

Ne K-edge ~ 870 eV

Ne Charge State vs IntensityRohringer & Santra, PRA 76, 033416 (2007)

@1050 eV

Probable Ne Charge State with hv

Rohringer & Santra, PRA 76, 033416 (2007)

@1μm beamsize

Power of TOFs: 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

Resonant Auger Electron Spectroscopy

• Interesting in molecules too – CO resonant Auger:

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

Spectator Auger

LCLS: HBr, Br2 2p & 2s Ionization

HBr 3d (ALS) Excitation/Ionization

2D Map; Angle-Resolved;e- TOFs

Ion Imaging : Fragmentation Decay Channels of CO22+ Subsequent to K-

Shell Photoionization and Auger Decay of CO2.

Identify different fragmentation mechanisms

Fragment Momentum Correlation Plots: Fragmentation Decay Channels of CO2

2+ Subsequent to K-shell Photoionization and Auger Decay of CO2.

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

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

hν=37.8 eV, <N>~100, I=3x1013W/cm2 @25 fs

In contrast with earlier studies in IR and VUV spectral regime, we find NO evidence for electron emission from plasma heating processes; Multistep ionization process is dominant

Proposed at 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?

4d Photoelectron Spectrum of Xe Clusters at h=135 eV

Velocity Map Imaging Coincidence System (PEPIPICO) @ ALS

Electron Detection Ion Detection

80 mm position-sensitive multi-hit hex-anode detector (Roentdek)

Rolles et al. Nucl. Instr. and Meth. B 261, 170 (2007).

Fragmentation of Rare Gas Clusters @ ALS

PEPIPICO coincidence map for photoionization at hv=216 eV

High Field Studies in Ions

Movable Ion-Photon Beamline for ions & size-selected clusters

Size Selected Production Size and Charge Selected Detection

Absolute cross sections: measurements of overlaps, photon & ion fluxes and detector efficiencies.

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

Li3+/Li2+<1%LCLS: S K-shell

S2+/S+ 60%

Th, Sim-Auger Int, K-Out H, S-Off; S-Up+Seq-Aug

PR A 72, 050701(R), 05

Ion StudiesIon Studies: : Measure electron spectra of ionic

species –

Si-→S+

•Si+

•Si2+

Si3+

Photoionization Dynamics of Clusters or Biomolecules

Biomolecules injected via electrospray

Time-Resolved Studies of Molecules

Pump-probe experiments of molecules (state-selected): - Launch a molecule on a particular potentially energy surface - Watch temporal evolution with angle-resolved inner-shell PES

Photodissociation Dynamics of I2-:

Pump-Probe Experiments•Short delay times photodetachmentaccesses bound vibrational levelsof I2 states

•Longer times,dissociation to I- + I

•Complete dissociation≡ photodetaching free I-

LCLS, Probe with >800 eV photons

I2

I2-

Photodissociation Dynamics of I2-

I- photoelectron spectrum

2P1/2 and 2P3/2 spin-orbit states of I.

Neumark et al. Chem. Phys. Lett, 258 (1996) 523.

Photodissociation Dynamics of I2-

Dissociation Time scale: Rise time of electron signal reaches 50% of its maximum value by 100 fs.

I 2P3/2

I 2P1/2

END

Molecular Fragmentation: Ion Momentum Imaging of Molecules (ALS)

Photodissociation Dynamics of I2-

Kolsoff et al.