Ultrafast AMO Physics at the LCLS X

ultrafast.stanford.edu
Ultrafast Short Wavelength Probes of
Inner Electron Sub-Cycle Dynamics in
Molecules
Philip H. Bucksbaum
Stanford PULSE Institute
Stanford University and
SLAC National Accelerator Laboratory
Menlo Park, CA
Collaborators
•
•
3/1/13
Bucksbaum group (including
alumni) : Adi Natan, James
Cryan, Mike Glownia, Doug
Broege, Andrei Kamalov,
Julien Devin, James White,
Song Wang, Jaehee Kim,
Limor Spector, Joe Farrell,
Brian McFarland, Vlad
Petrovic, Lucas Zipp, Ian
Tenney, Markus Guehr, Ryan
Coffee
•
Experimental groups contributing to our LCLS work:
Nora Berrah et al, Kalamazoo; Lou Dimauro et al, OSU;
Jon Marangos, Imperial College; Linda Young et al,
ANL; Hamed Merdji, CEA Saclay; Raimund Feifel,
Uppsala; Abbas Ourmazd et al., Milwaukee; AMO and
Laser group, LCLS; PULSE Institute: Bucksbaum
group, Guehr group; Reis group; Bogan group.
Theory contributions: Tamar Seideman group,
Northwestern; Alejandro Saenz group, Berlin; Martinez
group, PULSE Institute
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Strong fields at long and short wavelengths
both induce nonlinear dynamics in molecules
• Molecules are highly interactive multi-particle
systems.
• Strong optical fields couple states, induce ionization
and structural changes, ATI, HHG
• Short wavelengths excite inner electrons, leading to
exotic many-electron excited states, Auger relaxation.
• These ultrafast dynamics unite strong field HHG and
free electron laser science.
Laser Lab: hv=1.5 eV
LCLS: hv=1500 eV
T=3fs
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T=3as
3
3
High harmonic generation (HHG)
Pulse energies:
picojoules to nanojoules
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X-ray Free Electron Laser (LCLS)
Pulse energies:
millijoules
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Two sources: HHG and LCLS
Relativistic electrons
in strong magnetic fields.
Atomic electrons
in strong laser fields.
•Electron energy= γmc2
•Wavelength = λ
•Undulator period =λu
•Maximum deviation angle of the
electrons = K/ γ
λHHG
MAX
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−1
 3.17 F

I
~ 15 − 50nm
= hc 
+
P
2
 4mω L

2
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λFEL
λu  K 2 
 ~ 0.1 − 4nm
= 2 1 +
2γ 
2 
6
Two sources: HHG and LCLS
LCLS:
Sub-fs spikes, SASE
Power
HHG:
Attosecond pulse trains, attochirp
0
2
4
6
8
Time (fs)
10
12
14
Low bunch
charge
Nuhn, NIM A 429, 249 (1999)
Y. Ding, PRL 102, 254801(2009)
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Two sources: HHG and LCLS
HHG: Inner electron dynamics
on the 3 eV and 1 fs scale
LCLS: Inner electron dynamics
on the keV and few fs scale
Impulsive dynamics
If tunnel time
t < h/∆E
ΓK = σKFlcls ≈ 1015 s-1
Impulsive dynamics
If Auger time
t < h/∆E
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Coherent rotational revivals: tool for
aligning the molecule
U=-1/4 ∆α E2 cos2θ
Stapelfeld, Seideman, Averbukh, others
τ pump <τ rotation
Cryan, et al. PRA,
80, 063412 (2009).
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HHG in kicked N2
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The HHG spectrum changes with the alignment
angle
HOMO
Generate
90o Align
Generate
0o Align
H21 and H43
HOMO
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H21 and H43
McFarland et al,
Science 322, 1232 (2008)
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Align
Cutoff
Align
McFarland et al,
Science 322, 1232 (2008)
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Generate
Plateau
Generate
H21
13
Align
Cutoff
Align
McFarland et al,
Science 322, 1232 (2008)
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Generate
Plateau
Generate
H43
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Cutoff
Align
Align
McFarland et al,
Science 322, 1232 (2008)
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Generate
Plateau
Generate
H21 oblate distribution
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Plateau
Align
Cutoff
Generate
H43 oblate distribution shows
destructive interference
+
Harmonics produced by
different orbitals are
out of phase by
e-i∆E∆t ~ e-iπ
Farrell, J. P. Chemical Physics 366(1-3): 15 (2009).
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Stripping atoms at LCLS
Core ionization and Auger
relaxation strip the atom
“from inside out”.
P
A
Charge
P
A
P
P rate ~ Ixrays
A rate ~ Nelectrons
P
V
Time
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Ne10+ at the focus
Nature 466, 56 (2010)
• Full ionization of Ne is possible
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Auger electron energies observed in the molecular
frame from N2  N2+  N22+ at 1.1keV
0o
90o
Total
45o
(Cryan et al, J. Phys. B 45
055601 (2012))
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Transient state studies: N2++ Potential
Energy Surfaces
Shaded area: Frank-Condon
R. W. Wetmore and R. K. Boyd, J. Phys. Chem. 90,
5540 (1986).
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Transient state studies: N2++ Potential
Energy Surfaces
Shaded area: Frank-Condon
R. W. Wetmore and R. K. Boyd, J. Phys. Chem. 90,
5540 (1986).
t=47 fs = 0.09eV ~ N22+ 1Π u(v=1011)
t=21 fs = 0.19eV ~ N22+ X1Σg(v=34)
t=13 fs = 0.31eV ~ N2+ 2Σg(v=01)
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Example: searching for N2++ vibrational wave
packets probed by 800 nm dissociation.
N2++
N2++
N+
N+
Pump-probe jitter obscures
the femtosecond dynamics
Glownia, J. M., et al. (2010). Opt. Express 18(17): 17620-17630.
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Strong and Ultrafast: Hollow atoms
P
Charge
P
Double core holes form
when the photoionization rate
exceeds Auger
A
P
A
P
Time
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Hollow atom formation at LCLS
Hoener, M., L. Fang, et al. Phys.
Rev. Lett. 104(25): 253002 (2010).
Frustrated ionization in N2
M. Hoerner, N.
Berrah, et al.
LCLS, Fall 2009
Hoener, M., Fang, L., Kornilov, O.,
Gessner, O., Pratt, S. T., G\"Uhr,
M., Kanter, E. P., Blaga, C.,
Bostedt, C., Bozek, J. D.,
Bucksbaum, P. H., Buth, C., Chen,
M., Coffee, R., Cryan, J., Dimauro,
L., Glownia, M., Hosler, E., Kukk,
E., Leone, S. R., Mcfarland, B.,
Messerschmidt, M., Murphy, B.,
Petrovic, V., Rolles, D. & Berrah,
N.
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N2 from LCLS shows Double core
vacancies.
Single-site double core Auger
spectrum
Main Auger
ssDCH
Auger
Shake-Up
Auger
3/1/13
Cryan PRL 105, 083004 (2010)
x10
Cryan, J. P., Glownia, J. M., Andreasson, J., Belkacem, A., Berrah, N.,
Blaga, C. I., Bostedt, C., Bozek, J., Buth, C., Dimauro, L. F., Fang, L.,
Gessner, O., Guehr, M., Hajdu, J., Hertlein, M. P., Hoener, M., Kornilov,
O., Marangos, J. P., March, A. M., Mcfarland, B. K., Merdji, H.,
Petrovi\Ifmmode \Acutec\Else \'C\Fi, V. S., Raman, C., Ray, D., Reis, D.,
Tarantelli, F., Trigo, M., White, J. L., White, W., Young, L., Bucksbaum,
P. H. & Coffee, R. N.
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DNA photoprotection (thymine)
Hudock et al.,
J. Chem. Phys. A,
111, 85 (2007)
Potential energy
ππ*
ππ*
Perun et al.,
J. Chem. Phys. A,110,
13238 (2006)
100 fs
~ps
100 fs
nπ*
nπ*
100 fs
~ps
Excitation
Effective nuclear path
Effective nuclear path
Fast: 100 fs – relaxation from FC to minimum
Medium: ~ ps – tunneling through barrier
Fast: 100 fs – non-BOA dynamics
Medium: ~ ps – vibrational relaxation
Markus Guehr collaboration, McFarland, et al., arXiv:1301.3104 [physics.chem-ph]
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Pump-Probe Scheme
UV
PUMP
n
NONBOA
DYNAMICS
SXR
PROBE
∆t=?
TIME
π
AUGER DECAY
π∗
Ekin
Record Auger electron energies as function of pump-probe delay
DELAY
O 1s
O 1s
Markus Guehr collaboration, McFarland, et al., arXiv:1301.3104 [physics.chem-ph]
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Delayed Ultrafast X-ray Auger Probing: DUXAP
Thymine Auger spectra (BL8 ALS)
π∗
n
C
π
N
O
Auger Matrix element:
<φcore χcont|1/r12|φvalφval’>
O 1s
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Spatial sensitivity for valence orbital at core hole!
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Time Dependent Auger
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UV on – UV off/
(UV on + UV off)
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McFarland, et al., arXiv:1301.3104
[physics.chem-ph]
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Map of DNA photoprotection
ππ*
70fs
nπ*
400fs
200 fs
Ground
state
Excitation
Effective nuclear path
Fast: 100 fs – non-BOA dynamics
Medium: ~ ps – vibrational relaxation
Markus Guehr collaboration, McFarland, et al., arXiv:1301.3104 [physics.chem-ph]
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Strong field lasers and LCLS create and
probe ultrafast processes:
• X-ray induced core holes allow access to the fastest time
scales in atoms and molecules
• Strong field lasers and HHG can probe interelectron
dynamics in bonding electrons
• High time and spatial resolution of both tools can reveal
how bonds are made and broken
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Thanks!
•
•
3/1/13
Bucksbaum group (including
alumni) : Adi Natan, James
Cryan, Mike Glownia, Doug
Broege, Andrei Kamalov,
Julien Devin, James White,
Song Wang, Jaehee Kim,
Limor Spector, Joe Farrell,
Brian McFarland, Vlad
Petrovic, Lucas Zipp, Ian
Tenney, Markus Guehr, Ryan
Coffee
•
Experimental groups contributing to our LCLS work:
Nora Berrah et al, Kalamazoo; Lou Dimauro et al, OSU;
Jon Marangos, Imperial College; Linda Young et al,
ANL; Hamed Merdji, CEA Saclay; Raimund Feifel,
Uppsala; Abbas Ourmazd et al., Milwaukee; AMO and
Laser group, LCLS; PULSE Institute: Bucksbaum
group, Guehr group; Reis group; Bogan group.
Theory contributions: Tamar Seideman group,
Northwestern; Alejandro Saenz group, Berlin; Martinez
group, PULSE Institute
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