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Robert W. Schoenlein Materials Sciences Division Lawrence Berkeley National Laboratory Ultrafast X-ray Science: A New Frontier for Next Generation Light Sources SRI 2001 Workshop: Energy Recovery Linac Sources of Synchrotron Radiation

Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

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Page 1: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

Robert W. Schoenlein

Materials Sciences DivisionLawrence Berkeley National Laboratory

Ultrafast X-ray Science:A New Frontier for Next Generation Light Sources

SRI 2001 Workshop:Energy Recovery Linac Sources of Synchrotron Radiation

Page 2: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

• Developing Research Program in Ultrafast X-ray Science

• Femtosecond x-ray beamline(s) at the Advanced Light Source

C. BresslerM. CherguiU. Lausanne

R. AbelaSwiss Light Source - PSI

R.W. FalconeS. Johnson

A. LindenbergU.C. Berkeley

T. E. GloverP.A. HeimannH.A. Padmore

ALS Berkeley Lab

R.W. SchoenleinA. Cavalleri

H.H.W. ChongC.V. Shank

Materials Sciences Div. LBNL

A.A. ZholentsM.S. Zolotorev

Accelerator and FusionResearch Div. LBNL

A. BelkacemM. Hertlein

M. PriorChemical Sciences Div. LBNL

J. LarssonLund

Page 3: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

Scientific Motivation for Ultrafast X-ray Research

Existing third generation synchrotron sources:

Current state of the art from infrared through EUV:modelocked femtosecond lasers and amplifiers

• <10 femtosecond resolution (10-4 tsynch)

• powerful x-ray probes of ‘static’ structure of matter

• optical properties/valence electrons

• indirect probe of structural dynamics

Is there a scientific reason to measure structural changes with femtosecond resolution?

• high flux, high brightness, spectral range (10 eV-100 keV)

• temporal resolution ~100 ps

Page 4: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

time-resolved EXAFS, NEXAFS, surface EXAFS

delay

���������

�� �������

diffraction angle

��������

time delay

���������

�� �����

��

ordered crystals - phase transitions, coherent phonons

r

energy

���

Kedge

detector

time-resolved x-ray diffraction

� �������

f(r)

complex/disordered materials - chemical reactions

bonding geometrysurface dynamics

fundamental time scale for atomic motionvibrational period: 1/νvib ~ 100 fs

Structural Dynamics in Condensed Matter

• ultrafast chemical reactions

• ultrafast phase transitions

• surface dynamics

• ultrafast biological processes

Rapidly emerging filed of researchPhysics, Chemistry and Biology

Femtosecond X-ray Science

Page 5: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

Ultrafast Structural Dynamics in Solids

• solid-solid phase transitions

• order/disorder transitions (melting)

Ultrafast Molecular Dynamics

• structural dynamics of the transition state

• solvent/solute interactions (solvent structure)

Ultrafast Processes in Biology

structural dynamics/reactions at surfaces

magnetization and spin dynamics

Outline

Page 6: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

Solid/Liquid Phase Transitions on the Femtosecond Time Scale

Atomic disordering on a time scale of a vibrational period ?

• electron temperature >> lattice temperature

• no equilibration of vibrational modes (vibrational coherence)

• Lattice Instabilities - high density electron-hole plasma

Nonequilibrium conditions

Phase Transition

(femtosecond optical excitation)

temperature?

vibrational motion~105 cm/sec~1 Å in 100 fs

• heating at constant volume – Warm Dense Matter

e-e scattering e-phonon scattering phonon-phonon scattering

100 fs 1 ps 10 ps 100 ps10 fs1 fs

• “non-thermal” melting

laser (visible photons)

electron-hole plasma

lattice (electron-phonon coupling)

Conventional Laser Melting

Page 7: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

P. Stampfli and K.H. Bennemann, Phys. Rev. B 49, 7299 (1994).

thermal melting non-thermal melting

Diamond/zinc-blende structure unstable to shear forces (TA phonons)

Eb – cohesive energy per atom

ξo – electron-hole plasma density

Non-Thermal melting: Lattice Instability

Page 8: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

Laser Heated InSb Data

-40 -20 0 20 40 60

1.6

1.7

1.8

1.9

2.0

2.1

2.2

time delay (ps)

��������������������� �������

-40 -20 0 20 40 60 80

-60

-40

-20

0

20

time delay (ps)

���������� ��������

~ 10 ps delay

lattice expansion propagating at the sound speed

(300 fs, 30 keV probe)

electronbeam

90 µm

femtosecond x-ray pulses

∆θ

femtosecondlaser pulse

Thomson Scattering Source

Leemans et al., Phys. Rev. Lett., 1996.Schoenlein et al., Science, 1996.

Chin et al., Phys. Rev. Lett., 1999.

Page 9: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

Indication of Ultrafast Disordering• ~6 % reduction in integrated diffracted photons for τdelay<1 ps

• sub-picosecond formation of ~ 30 Å melt depth

• higher sensitivity to the surface7.5 keV photons from Thomson source (25 MeV e-beam)

InSb 12.8 degrees off (111)

7 7.2 7.4 7.60

50

100

150

200

250

x-ray photon energy (keV)

Gaussian fits-10 ps+1 ps+10 ps

-10 -5 0 5 10

0.90

0.95

1.00

1.05

time delay (ps)

������� �������������

�����

Chin et al., Phys. Rev. Lett., 1999.

Page 10: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

Ultrafast Structural Dynamics in Crystalline Solids

beyond Bragg studies of order disorder transitions

Femtosecond X-ray Spectroscopy (EXAFS and XANES)

• amorphous/polycrystalline materials

• surface sensitivity

• short-range order dynamics, coordination and bonding

• semiconductors - structural dynamics of semiconductor/metal transition

• graphite (diamond) - liquid carbon, diamond graphitization

Structural Dyanamics of Nanocrystal Materials

• reversible solid/solid phase transitions

Systems of interest

Page 11: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

WZRS WZ

RSRS WZ

pressure (GPa)

70

90

110

130

0 2.0 4.0 6.0 8.0

����������������!��

EA

PT

0 1 2 3 4 50

0.2

0.4

0.6

0.8

1

r (Å)

4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8-0.03

-0.02

-0.01

0

0.01

0.02

0.03

E (keV)

wurzite rocksalt

����

CdSe EXAFS

CdSe Nanocrystals: Solid-Solid Phase Transformation

A.P. Alivisatos et al. - U.C. Berkeley

Page 12: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

Ultrafast Chemical Reactions

Structural Dynamics of the Transition State

• intramolecular vibrational relaxation (IVR)

• internal conversion - IC

reaction coordinate������

reactant

photo-product

τIC < τIVR

reaction coordinate

������

reactant

photo-product

τIVR < τIC

Page 13: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

hνhigh-spin state

charge-transfer state

low-spin state

τ~700 fs

Fe

L

Fe

L

• ~10-15% increase in metal-ligand bond distances

• structural dynamics concomitant with changes in optical and magnetic properties

• structural dynamics - spin crossover and electron transfer

• mechanistic role in biochemical processes (cytochrome P450)

• magnetic and optical storage material

0 1 2 3 4 5

0.2

0.4

0.6

0.8

r (Å)0

7.2 7.25 7.3 7.35 7.4 7.45 7.5 7.55 7.6

-0.04

-0.02

0

0.02

0.04

E (keV)

low-spin (ground state) high-spin (photoexcited)

FeII EXAFS

����

FeII Spin-Crossover Molecules

Page 14: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

Ultrafast Chemical Reactions - Solvent Dependence

Ru – charge-transfer complex [Ru(bpy)3]2+

����

���� ���������

� ��� ��� ��� ��� ����

���

���

���

���

���

���

���

���

��������� ��

���

��

��������

���

����� ���� "����� ������ � ��#�$%�$& '#'$%�$& '������()�

$%�$& *+ � � ,,-,

$%�$%)$& ��� ��� ��� ./-0

$%�$%)$%)$& �.� ��� ��� �,)1

Femtosecond Anisotropy Measurements (optical)

Yeh, Shank, and McCusker, Science, 289 (2000)

Page 15: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

� �����

�������������

�������������

��

��

*�0� *�/� *)�� *))� *),� *)0� *)/�

����

����

) �������*�

2�3���4���5�����#��

( ��������#��-�-

"�����')

&�'����%)6

C. Bressler, M. Chergui et al. - U. LausanneA. Filipponi et al. - ESRF

Solvent-Solute Structural Dynamics

X- + hν →→→→ Xneutral + esol

Page 16: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

Structural Dynamics of Ultrafast Biological Processes

Role of protein environment in chemical reaction?

structure ⇔ dynamics ⇔ function

• large (and small) scale conformational changes → function

pump-probe techniques with laser and x-ray pulses

• light-induced reactions in bio-molecules

• transient changes in temperature, pressure, ph etc.

• proteins exist on a multidimensional energy surface

• dynamic measurements in structural biology (msec to femtosecond scale)

Page 17: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

Rhodopsin - photoreceptor for vision• cis-trans isomerization complete in 200 fs

Structural Dynamics of Ultrafast Biological Processes

• vibrationally coherent

7������������

*�� **� 0�� 0*�

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��

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�*�

)��

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,��

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0���

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Schoenlein et al. Science (1991)Wang et al. Science (1994)

Page 18: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

Measured ‘static’ Structure of Bacteriorhodopsin (M-state intermediate)

(2 Å resolution)

H. Luecke et al, Science, 286, 255, (1999) ALS Beamline 5.0.2

Page 19: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

Heme Protein Dynamics

• vibrationally coherent photodissociation - ultrafast optical spectroscopy

Zhu, Sage, and Champion, Science, 266 (1994)

• structural changes associated with ligand binding and dissociation?

• static EXAFS measurements of Fe-N distances in hemoglobinP. Eisenberger et al., Nature, 274 (1978)

Time-resolved Crystallography of CO-Mb Photolysis

Srajer et al., Science, 274, (1996) ESRF beamline ID9

photolysis τ<75 fsFe-His compression Tvib~150 fsHeme doming Tvib~430 fs

nanosecond resolution -> 100 ps

flux ~ 108 ph/pulse/0.1% BW

N

N

Fe

O

(1.8 Å resolution)

Page 20: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

Characteristics for Ideal Source

(1) temporal resolution ≤ 100 fs

• synchronization to laser trigger

(2) high average flux 108-1013 photons/sec/0.1% BW

(3) tunable 0.3 keV - 20 keV

(4) rep. rate: 100 Hz - 10 kHz

• high average brightness <1 mrad source divergence

X-rays for Ultrafast Structural Dynamics

• pulse duration

Page 21: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

�� � 7�����

bendmagnet

mirror����� x-rays

7�����

femtosecondelectron bunch

bend magnet beamline

30 ps electronbunch

femtosecondlaser pulse

spatial separationdispersive bend

�;

electron-photon interaction in wiggler

femtosecond x-rays

e-beam

Generation of Femtosecond X-rays from the ALS

Zholents and Zolotorev, Phys. Rev. Lett., 76, 916,1996.

Page 22: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

CalculatedElectron Density

Distribution

-3σx to +3σx +3σx to +8σx +4σx to +8σx

-1200-1000 -800 -600 -400 -200 0 200

60

80

100

120

140

160

delay (fs)-1200 -1000 -800 -600 -400 -200 0 200

80

100

120

140

160

180

200

220

240

260

delay (fs)-1000 -500 0 500 1000

1800

1900

2000

2100

2200

2300

2400

2500

2600

�����

delay (fs)

-1000 -500 0 500 1000 0

.2

.4

.6

.8

1.0

0

1

2

3

4

-4

-3

-2

-1

time (fs)

�#��

Schoenlein et al., Science, 287,2000

Femtosecond Pulses of Synchrotron Radiation

Page 23: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

Femtosecond X-ray Flux and Brightness

103 10

4

105

106

107

108

109

1010

1011

1012

photon energy (eV)

��������# #�-�:��;�

������ ����# #��)#����)#�-�:��;�

105

106

107

108

109

1010

1011

1012

Thomson Source: flux: 2x103 ph/s/0.1% BW brightness: 3x103 ph/s/mm2/mrad2/0.1% BW

undulator brightness (200 fs, 40 kHz)

bend magnet brightness (100 fs, 5 kHz)

(20 mm period, 1.0 T, 1 m length)

undulator flux (200 fs, 40 kHz)

bend magnet flux (100 fs, 5 kHz)

(20 mm period, 1.0 T, 1 m length)

Page 24: Ultrafast X-ray Science: A New Frontier for Next ......A New Frontier for Next Generation Light Sources ... Physics, Chemistry and Biology Femtosecond X-ray Science. Ultrafast Structural

ALS beamlines for ultrafast x-ray spectroscopy• BEND: 105 ph/s/0.1% BW, ~100 fs, 0.3-12 keV

• UNDULATOR: 108 ph/s/0.1% BW, ~200 fs, 0.5-10 keV

Time-resolved Measurements of Structural Dynamics in Condensed Matter

Scientific Applications for Femtosecond X-ray Pulses

fundamental time scale for atomic motion - vibrational period ~100 fs

Solid-State Physics• ultrafast phase transitions (solid/liquid and solid solid)

Chemistry• structural dynamics of transition state - kinetic pathway of reaction

Biology• structural dynamics - biological function and efficiency

• reaction dynamics in solution (dilute) Hb EXAFS >1012 photons (∆t, ∆E)

• structural dynamics of complex molecules and biomolecules LAUE >108 ph/pulse

Dedicated X-ray facility for studies of Structural Dynamics