LCLS
University of Californiaat San Diego
Uppsala University, Sweden University, Uppsala National Institutes of Health of Institutes National Laboratory National Brookhaven Brookhaven National Laboratory National Brookhaven California Institute of Technology of Institute California
Brookhaven National Laboratory National Brookhaven Stanford Synchrotron Radiation Laboratory Radiation Synchrotron Stanford
Femtochemistry Laboratory National Brookhaven Dan Imre, Anfinrud, Philip Arthur, John Hastings, Jerry Kao, Chi-Chang Neutze, Richard Mark Renner, Group, Wilson-Squire Zewail, Ahmed LCLS Description of static molecularof properties in terms bond lengths and angles has served us well. everyVirtually in biology new discovery and chemistry can be traceda to structure being solved.
A Chemist’s View of Nature View A Chemist’s LCLS Chemical transformations are about dynamics, i.e. rapid changesin bond lengths and bond angles. What needed is will is a tool that possible make a simple connection evolution. and the static picture between its time
Chemistry is about Motion about is Chemistry LCLS The ultimate goal of any molecularThe ultimate goal of any dynamics study is to produce a nuclear of the motion picture function of time. motions as a
Chemistry is about Motion about is Chemistry LCLS of reacting has been of reacting a BUT
in the process long-time dream long-time spatial information Femtosecond lasersfast enough are Capturing molecules Their greater than 200-nm wavelengthnot does allow for any
Spectroscopy of the Transition State Transition of the Spectroscopy LCLS resolution system that attempts to break that limit for the inability of lasersfor the inability of provide to the spatially needed Ultrafast Electron Diffraction (UED) is only the experimental Spectroscopy of the transition state is an to compensateSpectroscopyof the transition attempt
Spectroscopy of the Transition State Transition of the Spectroscopy LCLS What arethe time-scales? Whatthe are length-scales? Putting things in perspective
Temporal and Spatial Scales Spatial and Temporal LCLS Å Time in femtoseconds, distance in I + 2 CH OH + H → 2 → I
Temporal and Spatial Scales Spatial and Temporal 2 O 2 H CH LCLS willit possiblemapthe nuclear makemotions to out
LCLS with a resolution 0.1with of Å, which is clearly sufficient. TIME The verya systemsresolutiona few light require of time femtoseconds, while heavier ones can pulses be studied with a hundred femtosecondfew long. BOND LENGTH The
Temporal and Spatial Resolution Spatial and Temporal LCLS H. Zewail Ultrafast Electron Diffraction Electron Ultrafast
UED Experimental Set-up Experimental UED LCLS UEDwill never break the becausepsec limit time of the fundamental the relationship between in the electrons number of bunchand pulse length. tens picoseconds spatial resolution is the only tool with the requiredis and with temporal the only tool
I Photodissociation
2
LCLS femtoseconds
I-CH
2 The
UED CH UED LCLS time 6LJQDO LCLS +] 5DWH relative signals relative 3
LCLS &URVV VHFWLRQ )OX[ and the relative crossection; crossection; relative 2 W ∆ SV IV 8(' /&/6 time resolution; time resolution; Comparison between Ultrafast Electron Diffraction (UED) Comparison between Diffraction Electron Ultrafast resolutionis at 50 least times better. 1 The predicted signals are comparable the but
Comparison between UED and LCLS UED and between Comparison LCLS Exp 1. Gas phase photochemistry Exp 2. Condensedphase photochemistry Exp 3. Dynamics nanoparticles in
Proposed Experiments Proposed LCLS beam as a probe
Pump laser
LCLS
Probe LCLS Probe Sample CCD to initiate the process and the the process and the to initiate The femtochemistry experimentslaser ultrafast use an
Pump-Probe Experiments Pump-Probe LCLS Time resolved diffraction Time resolved Mie scattering (small angle scattering) • •
Experimental Approaches Experimental LCLS is ideally suited to suited is ideally
LCLS LCLS Photodissociation of an isolated of Photodissociation of the simplest is molecule diatomic reactions. chemical defined easily is t=0 is well wave-function initial The defined localized remains wave-function The reaction the throughout The investigate these reactions these investigate 5 t 4 t 3 t 2 t
1
0 t t
Absorption Absorption Raman Resonance
Experiment 1. Gas phase photodissociation reactions photodissociation phase 1. Gas Experiment LCLS will makewill it possible to The coupling nuclear between and electronic motion is a universal phenomenon dominates that almost all photochemistry. is essentialIt we that develop an of this behaviorintuitive picture LCLS directly observe this complex motion.
Nuclear and Electronic Coupling is Universal Phenomenon is Universal Coupling Electronic and Nuclear LCLS The solvent cage changes the dynamics and provides a means reactions. to study recombination
Experiment 2. Condensed phase photochemistry phase 2. Condensed Experiment LCLS .) 300fsec 100psec 200psec 200psec
et al 80 psec time80 psec resolution from resolution 2 3 4 0 Radiation Facility Radiation European Synchrotron European 1 2 3 4 Diffuse scattering X-ray with ) A 2 u π B 1 in dichloromethane (Neutze X 2 I 3 4 0 1 Internuclear separation ( A/A' 2.0 3.0 4.0 5.0
0
30 20 10
) cm (10 Energy
-1 3
Third Generation Sources Have a Limited Time Resolution Time Limited a Have Sources Third Generation LCLS .) Time nsec Time
et al
0.0 0.2 0.4 0.6
1 0 1 Relative signal Relative ) A 2 u π B 1 in dichloromethane (Neutze 2 I X 3 4 0 1 Internuclear separation ( A/A' 2.0 3.0 4.0 5.0
0
30 20 10
) cm (10 Energy
-1 3
An Example from E S R F R from E S An Example LCLS Nanoparticles Semiconductorsnanocrystals and metal also known as quantum dots possess unique size-dependent electronic propertiesquantumand optical size result from that confinement of charge carriers and very large surface to volume ratios. These propertiesapplications hold great promise in for areas such as microelectronics, electro-optics, photocatalysis, andphotoelectrochemistry. They are also area surface large their of because attractive, particularly and fast chargetransport properties,photovoltaics for chemicaland photo-degradation wastes of and pollutants.
Experiment 3. Dynamics in nanoparticles in 3. Dynamics Experiment LCLS . will maketo conduct it possiblewill
LCLS
single particles experiments on The size distribution problem size distribution The Under most experimental conditions size dependent properties tend to be maskedthe presence by of a wide size distribution. of the The high intensity effect The solvent Under most experimentalhigh conditionssurface the to To solvent. to sensitivity extreme in results ratio volume reproducible,provide a controlled, for well defined, inert scattering low backgroundenvironment, with particles be will study. for crystals Ne in isolated
Experiment 3. Dynamics in nanoparticles in 3. Dynamics Experiment LCLS
LCLS LCLS Melting a single nanoparticle
3. Melting single nanoparticles single Melting 3. Laser photon
Experiment LCLS
LCLS
LCLS scattering spectrum at 1.5 Å will LCLS Signal Signal Signal t=0 t=1 t=2 t=3 Pump Probe Probe Probe Laser photon The time evolution of the Mie possiblemake particle it to map out internal vibrational modes asas surface well capillary modes of a single nanoparticle.
Experiment 3. Vibrations in nanoparticles 3. Vibrations Experiment LCLS 3.0 2.8 2.6 2.4 2.2 2.0 1.8 Particle Diameter (nm) 1.6 1.4 Mie scattering spectrum at 1.5 A Mie scattering spectrum at 1.5 1.2 1.0 0 50
550 500 450 400 350 300 250 200 150 100
Scattering at 1.5 Å at 1.5 Scattering Intensity Simulated scattering intensity at a single angle as a function of function a as angle single at a intensity scattering Simulated fixed for a is obtained spectrum rich A similarly size. particle angle. of scattering a function as size particle and size particle in to changes sensitive extremely are spectra Mie shape.
Simulation of Mie Simulation LCLS is the only tool that will, in the foreseeablein the future,is that will, the only tool problems in the canapplied of berange to a wide
LCLS LCLS make it possible observenuclear a to motion during it make reaction in real time. The were upon here, touched which someof chemistry, of field photodissociation most fundamental the from reaction, to properties thecharacterizing of applied problem more the of nanoparticles. The
Femtochemistry at the LCLS : Conclusion at the Femtochemistry