AMO & Chemistry @ LCLS IApril 10, 2019Linda YoungDistinguished Fellow/Argonne National Laboratory

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October 1, 2009 —› November 27, 2018

2AMO First Users AMO Last Users

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Timeline - some experiments in AMO and chemistry

2009

Ultraintense soft x-ray inteactions with atoms,

molecules, clusters

Soft x-ray spectroscopy

Surface catalysisSolution chemistry

13 14 15 169 10 11 125 6 7 81 2 3 4

Aligned molecule imaging Atomic inner–shell laser

Stimulated Raman Scattering

Double core hole spectroscopy

Streaking pulse characterization

Hard x-ray spectroscopy

spin state changes

C60 nanoplasma

Coherent structural dynamics with

diffuse scattering

Quantum vortices

RIXSPhotoinduced

electron transfer

Solvation dynamicsSoft x-ray atom

specific core level spectroscopy

X-ray optical cross correlation

Molecular moviering opening

X-ray induced dynamics in

clusters

Ultraintense hard x-ray interactions

Two-color pump/probeIn-flight holography

Femtosecond emission

spectrosocpy

Bond formation at metal surfaces

Time-domain Auger

Angular StreakingNonlinear Compton

Catalytic N2 formation

Vitamin B12

Imaging femtosecond nanoplasma

dynamics

Coherent dynamics C60

Surface chemistry driven by soft x-rays

Electronic to nuclear

relaxation core excited state

Donor-bridge-acceptor

Conical intersections

Nuclear nonlinear

optics

Attpsecpmd scattering

Femtosecond RIXS

Ionized water

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LCLS – more intense than …

§ 100 suns on the Earth’surface focused to ~ 1 cm2

§ 10 billion synchrotron pulses

§ Capable of focussed intensity of 1020 W/cm2 at ~1 Å

§ Compare to atomic unit of intensity of 3.5 x 1016 W/cm2

Stohr PRL (2016)

Unprecented intensity at short wavelengths – what happens?

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A prime motivation for the LCLS: diffract-before-destroy

Neutze, Wouts, van der Spoel, Weckert, Hajdu - Nature 406, 752 (2000)

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LCLS 1st experiment

Nature of electronic response to 105 x-rays/Å2

80 - 340 fs800 - 2000 eV~1018 W/cm2

This work establishes the dominant interaction as sequential multiphoton absorption.

Guided by theoryRohringer & Santra PRA (2007)

ObservationsFull stripping of neon atom in single pulseHollow atom formationIntensity induced transparency

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Making it happen …

Oct 1, 2009 ~9 am – Leak Checking

Sep 30, 2009 ~3 pm – Pre-run meeting

Linda: Can you change the pulse duration?

Paul & Zhirong: Sure no problem.

Linda: How long does it take?

Paul: 30 mins

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What about resonances? Can theory be predictive?

LCLS 5th experiment: Unveiling and driving hidden resonances in neon

Kanter … PRL (2012)

LCLS 8th experiment: Ultra-efficient ionization of heavy atoms (Xe)

Rudek… Nat Photonics (2012)

Predictive theory including resonancesHo… PRL (2014)

Experiment + predictive theory including resonances and relativistic effects w/ hard x-rays

Rudek… Nat Commun (2018)

These works establish a predictive theory for ultraintense x-ray interactions with atoms that are used in an atomistic approach to calculate coherent diffractive imaging of macromolecules including damage.

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Explore ultraintense hard x-ray ionization in molecules

Nature of molecular response to 105 x-rays/Å2

8.3 keV~30 fs

~1020 W/cm2

Compare ionization of isolated heavy atom with embedded heavy atom.

Observe that ionization of a moleculeis considerably enhanced compared to an individual heavy atom with the same absorption cross-section –unlike earlier studies.

Iodomethane Iodobenzene Xenon

Rudenko… Nature (2017)

This work uncovers a new mechanism for efficient x-ray ionization: ultrafast charge transfer within molecule refills core holes providing further targets.

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AMO – more than …

Atomic inner-shell laser

Timing tools for x-ray & laser pulsesIn-flight x-ray holography

Two-color probes of x-ray processes

Rohringer…Nature (2012)

Gorkhover…Nat Pho (2018)

Picon…Nat Comm (2016)

Hartmann…Nat Pho (2014)

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Chemistry

Chemistry is the scientific discipline involved with elements and compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during a reaction with other substances.

Wikipedia

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What has light ever done for chemistry ?

- Induces important biological reactions- Vitamin D synthesis- DNA damage

- Promotes electron transfer for device design- Molecular switches- Solar energy harvesting

- Provides energy to drive uphill processes

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What has LCLS done for photochemistry ?

Molecular moviering opening

Molecular switchlow-spin to high-spin Chemical bond

formation

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Photoproduction of Vitamin D – ring opening reaction

UVB; 290–315 nm

7-Dehydrocholesterol Vitamin D3

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First “molecular movie” of a ring-opening reaction

Minitti … PRL (2015)

Optical pump/x-ray elastic scattering probeGas phase CHD

Optical: 267 nm, 65 fs, 4-8 µJ, 100 µm X-ray: 8.3 keV, 30 fs, 1012 photons, 30 µm

Detector q range: 1 - 4.2 Å-1

Previously studied with UV spectroscopies, but correlation between time constants and molecular structures was absent.

p excitation causes rapid expansion of carbon bonds followed by rupture in two oscillations - 80 fs

Demonstrates feasibility of x-ray movies for gas phase chemistry and structural dynamics – direct input to theories of non-adiabatic dynamics.

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How does single photon low- to high-spin conversion occur?

Model molecular switch: [Fe(bpy)3] 2+

Singlet to quintet state in ~100 fs following photoexcitation of a MLCT state

Pass through a triplet state?- X-ray emission spectroscopy- UV spectroscopy

Control excited state dynamics?- Ligand effects- Solvent effects

Extend lifetime of charge transfer state to create practical photocatalyst

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How does single photon low- to high-spin conversion occur?

XANES spectra have varying sensitivity to electronic, coherent and incoherent structural changes

Prominent 265 fs oscillations observed at many x-ray absorption energies.

Optical pump/x-ray total fluorescence probe30 mM solution phase [Fe(bpy)3] 2+

Optical: 530 nm, 50 fs, <2.2 mJ/mm2

X-ray: 7.1 – 7.18 keV, 20 fs, monochromaticTime resolution: 25 fs (RMS)

Lemke … Nat Commum (2017)

This work demonstrates that time-resolved XANES can reveal coherent and incoherent ultrafast dynamics along with the change of electronic state.

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Tracking the ultrafast creation of a catalyst

Optical pump/x-ray dispersed emission probe

1 M solution phase Fe(CO)5

Optical: 266 nm, 100 fs, 5 µJ, 100 x 400µm2

X-ray: 705-715 eV, 160 fs, 1010photons/pulse

Time resolution: 300 fs

Optical pulse ejects a CO from Fe(CO)5 to form a 16-

electron Fe(CO)4 - a homogeneous catalyst.

Time-resolved RIXS spectra probe the evolving frontier

orbitals: metal-centered dp –› ds*

Calculated RIXS signatures for various intermediates are

used to identify kinetic pathways.

This work finds a new excited singlet state, resolving debate about importance of various spin channels, and demonstrates a broadly applicable & complementary method to structural probes to chemical dynamics. Wernet… Nature (2015)

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Probing the transition state region in catalysis

The work provided first experimental characterization of the transition state in a surface catalytic reaction and provides direct input into the theory of heterogeneous catalysis

Laser pulses heat electrons in the Ru substrate that thermalize (1500 - 3300 K).

Energy transfer from electron to phonon to adsorbate cause the reaction between CO and adsorbed O atoms in > 1ps

XAS spectral changes for the transition state consistent with DFT calcs

Oström … Science (2015)

Optical pump/x-ray absorption probeO and CO on Ru(0001)

Optical: 400 nm, 170 fs X-ray: 528 - 546 eV, 80 fs, dE/E=2000

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Academically – non-adiabatic dynamics are a grand challenge

LCLS with its ability to determine nuclear and electronic dynamics on their natural timescales is poised to markedly advance predictive theories for non-adiabatic processes.

Potential energy surface is the central concept for understanding chemical reactions.

Adiabatic (Born-Oppenheimer) PES a 3N hypersurface is a function of all nuclear positions –mapped w/ high accuracy for larger & larger systems.

BUT – many events cannot be described w/ BO

Non-adiabatic electronic transitions between PESs are ubiquitous and important …

conical intersectionsintersystem crossinginternal conversionelectron transfer ….

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Preparing for the Attosecond Frontier with LCLS- II

Attosecond metrology @ LCLS Attosecond photoionization dynamics

X-ray photoionization into a continuum dressed by a circularly polarized laser field yields an angularly streaked spectrum to recover single shot attosecond pulse structure and phase.

--- N. Hartmann… Nat Photon (2018)

X-ray photoionization of NO in the presence of a circularly polarized laser field shows a photon energy dependent photoemission time delay of N vs O – suggesting shape resonance trapping.

--- J. Cryan … to be published

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Thanks from all the AMO and Chemistry Users

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Thanks to the phenomenal accelerator, beamline, data teams

Accelerator team

Controls team

Main Control Center - Oct 2009 AMO Control Room - Oct 2009

Data team

Laser team

All the instrument scientists!

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Happy 10th anniversary LCLS !

What are you looking forward to with LCLS-II?

Phil BucksbaumThe top of my list is attosecond science. Once we begin user operations on LCLS-II, we will soon see real movies that display the kinds sub-femtosecond correlated electron and atomic motion that have only been imagined thus far in simulations and theoretical models. Innovations like XLEAP and attosecond axial streak cameras are paving the way for this, so that we won't have to wait another decade past first light for the tools to catch up. These movies, once we see them, will not merely validate theory. They will produce their own new surprises and new "Aha!" moments of insight, just as we have seen in the last decade with LCLS, and other breakthrough technologies (LIGO, for example). I'm really looking forward to that.

Kelly GaffneyMoving forward, I am excited to use metal & ligand soft x-ray spectroscopy to measure time dependent changes in bonding (covalency) as a function of a time dependent geometry. In this way, I think we can directly access the extent of coupling (adiabaticity) between electronic states as a function of geometry. Does the charge distribution change continuously as a function of geometry (Born-Oppenheimer) or undergo discrete jumps over a narrow range of geometry (non-Born-Oppenheimer) and what molecular properties determine which scenario dominates.

“I am excited to discover new ideas and make new friends – with both people and molecules”--- Kelly