Atomic, Molecular and Optical Science
Transcript of Atomic, Molecular and Optical Science
Atomic, Molecular and Optical Science
AMO OverviewIntense short pulses of X-ray radiation created by the LCLS free electron
laser (FEL) will interact with electrons in the sample being illuminated to
create states of matter that have not been observed previously. The goal
of the Atomic, Molecular and Optical (AMO) science instrumentation at the
LCLS is to explore the interaction of this intense radiation with the simplest
forms of matter, namely atoms and molecules, to gain an understanding of
how their electronic structure responds. Femtosecond X-ray pulses from
the LCLS also offer the opportunity to follow the evolution of chemical re-
actions on their natural time scales using well established and powerful
tools such as ion, photoelectron, Auger and X-ray emission spectroscopy.
A suite of instrumentation including focusing optics, gas delivery systems,
electron, ion and photon spectrometers and a synchronized high-power
laser are currently being designed for the AMO end-station.
AMOL I N A C C O H E R E N T L I G H T S O U R C E
Main Contacts:
Name John Bozek� Instrument ScientistPhone 650-926-5091Email [email protected]
Name Christoph Bostedt AMO Instrument ScientistPhone 650-926-2591Email [email protected]
Name Jerry Hastings LUSI Project DirectorPhone 650-926-3107Email [email protected]
AMO Complete Assembly
AMO at the LCLS
LCLSComplex
AMO/Near Hall/Hutch 1
Scienti�c Application
Techniques
Sample Environment
Focusing Capability
Beam Size at Sample
Energy Range
Energy Resolution ΔE/E
Magnetic BottleElectron Spectrometer
Pulse Energy Monitor
Beam Screens
Atomic, molecular and optical science with ultrafastand ultraintense x-rays at the lcls
Scienti�c Capabilities
Photon Beam Properties
Diagnostics
Electron time-of-�ight spectroscopy
Ion time-of-�ight spectroscopy
Ion imaging
Ion momentum spectroscopy
X-ray emission spectroscopy
Skimmed supersonic pulsed gas jet
Elliptically bent Kirkpatrick-Baez mirrors
~1-2 μm at interaction region
825-2000 eV
~0.2% (inhomogeneous fel bandwidth)
(no monochromator)
Measures the photon energy and bandwidth of the X-rayswith a high e�ciency electron spectrometer
Measures the energy of each pulse
Measures position and size of beam in the far �eld
AT O M I C , M O L E C U L A R A N D O P T I C A L S C I E N C E
AMO Characteristics
AMO Science FocusThe interaction of ionizing radiation with matter has been a topic of much study
since Hertz observed (1887) and Einstein described (1905) the photoelectric ef-
fect. While the mechanisms of excitation and ionization following the illumina-
tion of a sample with a weak beam of X-rays are well understood, little is known
about the processes which occur when an intense beam of X-ray radiation strikes
a target. Novel multi-electron processes are expected to occur and states of mat-
ter never before seen created. The goal of the AMO instrument is to study the
interaction of the intense, short pulses of X-rays from the LCLS with the simplest
forms of matter; atoms, molecules and clusters, to expand the understanding of
which processes are important at different intensity regimes.
The extremely short pulses of X-rays from the LCLS provide a unique capability
to study chemical processes at their natural time-scale. X-rays, such as those pro-
duced by the LCLS, interact with electrons in matter, exciting or ionizing them or
scattering from them. Electron dynamics occur on the attosecond time-scale,
much faster than the duration of the LCLS pulse. Nuclear dynamics (the motion
of nuclei in a molecule) occur on the femtosecond time scales, however, a time
scale that the LCLS is ideally suited to study, and the electronic structure of a
molecule adjusts to the changing nuclear structure. Furthermore, photoion-
ization of inner-shell electrons provide a site-specific probe of the electronic
structure of a molecule, i.e. allowing electrons from a carbon atom to be dif-
ferentiated from those of an oxygen atom. The LCLS is therefore a powerful tool
for studying the motion of atoms in molecules reactions initiated by an external
trigger (i.e. laser).
The unique capabilities of the LCLS AMO instrument will address a wide variety of science such as:
• Investigate Multiphoton and High-field X-ray Processes in Atoms, Molecules and Clusters
• Multi-photon Ionization/ Excitation in Atoms/Molecules/ Clusters
• Accessible Intensity on Verge of High-field Regime
• Study Time-resolved Phenomena in Atoms, Molecules and Clusters Using Ultrafast X-rays
• Inner-shell Side Band Experiments
• Photoionization of Aligned Molecules
• Temporal Evolution of State-prepared Systems
The AMO instrument is separated into four vacuum chambers, each with their own specific purpose:
• Single Pulse Shutter
• Focusing Optics
• High-field Physics End-station
• Diagnostics Chamber
In addition, a ~2mJ 120Hz 800nm pulsed laser (with harmonics) will be provided along with a control and data acquisition system ca-pable of measuring data from each pulse.
AT O M I C , M O L E C U L A R A N D O P T I C A L S C I E N C E
P
P
Gas Jet
Up
to A
ir Va
lve
BypassValve
Di�erentialPumping
LaserIntroduction
Mirror
BeamFocus
Paddle
ElectronSpectrometers 5x
Telescopeand Camera
X-ray EmissionSpectrometers
1 of 3Ion Spectrometers
High-�eld Physics End-station
Turbo
RemoveableBeam Stop
BeamViewingPaddle
PP
P
PrimaryPump Sample P
PrimaryPump
TurboRG
A
Slow SpeedCamera
Slow SpeedCamera
P
P
IonPump
Single Pulse Shutterwith Beam Paddle
Single Pulse Shutter
Slow SpeedCamera
P P
P
IonPump
PrimaryPump
Turb
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TSP
KB Mirror 1 and 2
Focusing Optics
Scanning Slits (2)with YAG Paddle
Slow SpeedCamera
Magnetic BottleElectron Spectrometer
X-ray EmissionSpectrometers
GasNeedle
Diagnostics Chamber
P P P
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PrimaryPump
Turb
o
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Di�erentialPumping
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PrimaryPump
Turbo
RGA
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ir Va
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Up toAir Valve
BeamViewingScreen
120 HzCameras
FixedBeamStop
Slow SpeedCamera
BeamViewingScreenTotal
PowerMeasurement
AMO CompleteAssembly
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AMO Assembly Breakdown
AT O M I C , M O L E C U L A R A N D O P T I C A L S C I E N C E
Single Pulse Shutter:The first small chamber will house a single pulse shutter that can be used to allow
only a single FEL pulse pass through to the experimental chambers. A millisec-
ond shutter from azsol GmbH (http://www.azsol.ch/index.php?p=home&lg=en)
will be incorporated into the vacuum chamber on a translation stage to allow
insertion into the beam.
Focusing Optics:Two elliptically bent mirrors will be used to image the FEL beam into the experi-
mental chamber. Dynamically bent mirrors can be adjusted to focus the beam
into either the interaction region in the high-field physics chamber or the diag-
nostics chamber, depending upon the experimental requirements.
High-field Physics End-station:The main experimental chamber of the AMO instrumentation includes the ma-
jority of the experimental capabilities. A skimmed pulsed gas jet is used to intro-
duce sample gas into the chamber where it will be ionized/excited by X-rays from
the LCLS. Several spectrometers will detect the results of the interaction of the
FEL radiation with the sample, including electron, ion and X-ray spectrometers.
A set of five electron time-of-flight spectrometers will be arrayed around the in-
teraction region to measure the energy and direction of the ejection of electrons
from the sample. One of three possible ion spectrometers, either a simple time-
of-flight, a velocity map imaging, or a momentum resolving ion spectrometer,
will also be mounted simulataneously, providing a means of measuring both
ions and electrons from each shot. Eventually two X-ray spectrometers will be
available to measure fluorescence from the samples, although they will have to
be fit in place of the electron spectrometers when in use.
Diagnostics Chamber:A separate diagnostics section is being designed to measure the parameters of
the X-ray FEL on a pulse-by-pulse basis. A magnetic bottle electron spectrom-
eter will be used to measure the photon energy and bandwidth of each pulse.
Ce:YAG beam screens will be used to image the beam downstream of the focus
and a thermal energy monitor used to monitor the intensity of each pulse. These
tools are designed to provide information about each pulse to aid in the inter-
pretation of the data obtained in the upstream chamber.
AT O M I C , M O L E C U L A R A N D O P T I C A L S C I E N C E