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

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 construction
category B: science
category 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
John Bozek LBL
Roy Clarke UM
Paul Fuoss ANL
Chris Greene U Colorado
Bertold Kraessig ANL
Dan Neumark UC Berkeley
Steve Pratt ANL
John Reading Texas A&M
Steve Southworth ANL
Linda Young ANL
Musahid Ahmed LBL
Philip H. Bucksbaum SU/SLAC
Todd Ditmire UT Austin
Ernie Glover LBL
Elliot Kantor ANL
Steve Leone UC Berkeley
Gerhard Paulus Texas A&M
Alexei Sokolov Texas A&M
David Reis UM
Linn Van Woerkom OSU
~ Twenty Additional Scientists Expressed Interest at
the October 2004 Workshop
Update on AMO Organization/Activities
1.
2.
3.
4.
5.
Instrument Scientist, John Bozek, Hired (Jan 2006)
Regular Teleconference (Berrah, Bozek, DiMauro, Young)
N. Berrah on Sabbatical FY06
Periodic visits by DiMauro/Berrah
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.
5.
6.
7.
8.
Ion (positive/negative) studies
Pump-probe, X-X or X-laser or X-e
Raman processes
Cluster dynamics (Diffraction of size-selected clusters)
Photoionization dynamics of biomolecules
Science discussed at 2004 October AMOS forum
Ken Taylor (Ireland)
David Reis (UM)
Robin Santra (ITAMP)
Anders Nielsson (SSRL)
Chris Greene (UCB)
John Bozek (ALS, LBNL)
Ali Belkacem (LBNL)
Keith Nelson (MIT)
Ernie Glover (LBNL)
Elliott Kanter (ANL)
Possibilities for few- and many-electron atoms &
ions in XFEL pulses
Synchronization issues for pump-probe
experiments at LCLS
Cluster physics at high photon energies
Time resolved spectroscopy for studies in surface
chemistry and electron driven processes in
aqueous systems
Multiphoton ionization processes in free atoms
and clusters
Atoms, molecules, clusters and their ions studied
with two or more Photons
Inner-shell ionization and de-excitation pathways
of laser-dressed atoms and molecules
Give him 10 minutes max and then let's get back
to reality
X-ray/optical wave mixing
Hollow neon atoms
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:
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:
Auger Decay
Photodetachment
(or Ionization)
Auger Decay
Sequential
(or “Cascade”)
Multi-Auger
Decay
Simultaneous
Double-Auger Decay
( 3-10% of single Auger)
Some Examples
High Field Studies in Atoms
X-Ray Strong Field Experiment
x-ray multiphoton ionization
photoionization
correlated ionization
Auger
sequential
2-photon, 2-electron
Low-Frequency Physics → High Frequency
IR:
Low frequency regime
VUV FEL:
Intense photon source
XFEL FEL:
Highly ionizing source
- Ip
- Ip
1015 W/cm2
• Keldysh parameter  <<1
• Tunnel / over the barrier
ionisation
• Ponderomotive energy 10
– 100 eV

- Ip
10x20 W/cm2
1013 W/cm2
• Keldysh parameter  >>1
• Multi-photon ionisation
• Ponderomotive energy
10 meV
Optical Frequency
Tunneling Frequency
• Angstrom wavelength
• Direct multiphoton
ionisation
• Secondary processes
= (Ip/2Up)1/2 -1;
Up=I/4ω2 (au)
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
FLASH Experiments
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.
TOF Spectrum for Atomic Xenon Multiphoton Ionization
(Wabnitz et al.’05 )
Wabnitz et al. ‘05
First LCLS Experiment: K-Shell in Ne
1. Photoionization
2. Auger Decay
3. Sequential Multiphoton Ionization
4. Direct Multiphoton Ionization
Theory:
LCLS
Double-K ionization in Ne due to
absorption of 2-photons by 1 atom for
hγ>932 eV is predicted to be 100%
Ne K-edge ~ 870 eV
The probability of twophoton absorption by 1s2 shell accompanied by the
creation of double 1svacancies predominates
over the probability of the
process of two-photon oneelectron excitation/ionization
of the 1s2 shell in the range
of x-ray photon energies ≥
930 eV.
2 e-out
1e-out
Ne Charge State vs Intensity
Rohringer & Santra, PRA 76,
033416 (2007)
@1050 eV
Probable Ne Charge State with hv
@1μm beamsize
Rohringer & Santra, PRA 76,
033416 (2007)
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
HBr 3d (ALS)
Excitation/Ionization
2D Map; AngleResolved;e- TOFs
LCLS: HBr,
Br2 2p & 2s
Ionization
Ion Imaging : Fragmentation Decay Channels of CO22+ Subsequent to KShell Photoionization and Auger Decay of CO2.
Identify different
fragmentation
mechanisms
Fragment Momentum Correlation Plots: Fragmentation Decay Channels of
CO22+ Subsequent to K-shell Photoionization and Auger Decay of CO2.
High Field Studies in Clusters
Cluster Studies at FLASH in Hamburg
Cluster Studies, FLASH
Xenon Cluster size 2500 atoms
13
PFEL=2.5*10
2
6
7
W/cm
8
Tpuls=50 fs
FEL=98 nm
Intensity (arb. units)
3
4
5
12
6*10
2+
Xe
11
6*10
 Unusually high energy
absorption in cluster
 Fragmentation starting at
1011 W/cm2
10
8*10
+
Xe
10
2*10
200
400
600
800
Time of flight (ns)
Wabnitz et al, Nature 420, 482 (2002)
Molecular dynamics simulations indicate
that standard collisional heating cannot
fully account for the strong energy
absorption.
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
hν=37.8 eV, <N>~100, I=3x1013W/cm2 @25 fs
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) 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?
4d Photoelectron Spectrum of Xe Clusters at hn=135 eV
Velocity Map Imaging Coincidence System (PEPIPICO) @
ALS
Electron Detection
Ion Detection
80 mm position-sensitive multi-hit hexanode 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)
S2+/S+ 60%
LCLS: S
K-shell
Li3+/Li2+<1%
PR A 72,
050701(R), 05
Th, Sim-Auger
Int, K-Out
H, S-Off; S-Up+Seq-Aug
Ion 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
photodetachment
accesses bound
vibrational levels
of I2 states
•Longer times,
dissociation to I- + I
I2
•Complete dissociation
≡ photodetaching free I-
LCLS, Probe
with >800 eV
photons
I 2-
Photodissociation Dynamics of I22P1/2 and 2P3/2 spin-orbit states of I.
I- photoelectron
spectrum
Neumark et al. Chem. Phys. Lett, 258 (1996) 523.
Photodissociation Dynamics of I2I 2P3/2
Dissociation Time
scale: Rise time of
electron signal
reaches 50% of its
maximum value by
100 fs.
I 2P1/2
END
Molecular Fragmentation: Ion Momentum
Imaging of Molecules (ALS)
Photodissociation Dynamics of I2-
Kolsoff et al.