Matthias Uiberacker
description
Transcript of Matthias Uiberacker
Matthias Uiberacker
Brijuni Conference, 31. August 2006, Brijuni Islands, Croatia
Sampling electron dynamics in atoms in real time with sub-femtosecond resolution
Prof. Ferenc Krausz
Dept. f. Physik, Ludwig-Maximilians-Universität München, Germany
Max-Planck-Institut für QuantenoptikGarching, Germany
Institut für PhotonikTechnische Universität WienWien, Austria
attosecond physics aims at gaining insight into the motion of electrons on atomic scales
&
of electronic motion in atoms, molecules, solids and plasmas
&
of electronic motion in atoms, molecules, solids and plasmas
0.00.0 0.10.1 0.20.2 0.30.3 0.40.4 [nanometers][nanometers]
e-e-
e-e-
direct controldirect control real-time observation real-time observation
time (s)
10-18 10-15 10-12
10-15
10-12
10-9
space (m)
molecules & solids
atoms
mic
ros
cop
y, d
iffr
acti
on
the microcosm: imaging in space and time
nuclearstructure &dynamics
attosecondmetrology
attosecondmetrology
femtosecondmetrology
atomsatoms
molecules
electronselectrons in
in
attophysicsattophysics
high–speed photography of microscopic processes:
time–resolved pump-probe spectroscopy
a sampling system with sub-fs resolution
what to do?
utilizing pump/probe techniques
ultrashort visible laser pulses are close to the wavecycle-limit of pulse duration (1-3fs).
..but, can be used to produce shorter (sub-fs) xuv pulses (high harmonic generation)
efficiency for 2 sub-fs xuv pulses is not sufficient yet
pump pulse and probe pulse need to be short enough to freeze the motion of electrons
using the electric field of laser pulses for probing with sub-fs resolution
= a(t)cos(ωLt + φ)
a(t)a(t)
T0 2.5 fsT0 2.5 fs
T0 /4 625 as (@ 0 0.75 µm)T0 /4 625 as (@ 0 0.75 µm)
E(t)
requires stabilization and control of carrier-envelope phase in combination with a weak sub-fs xuv pulse ->
pump/probe measurements with sub-fs resolution!
waveform-controlled few-cycle light opens the door to steering & capturing electrons on an attosecond timescale
A. Baltuska, T. Udem, M. Uiberacker, M. Hentschel, E. Goulielmakis, C. Gohle, R. Holzwarth, V. Yakovlev, A. Scrinzi, T. W. Hänsch, F. Krausz, Nature 421, 611 (2003)
ultrabroadband dispersioncontrol with chirped multilayers
R. Szipöcs, K. Ferencz, Ch. Spielmann, F. KrauszOpt. Lett. 19, 201 (1994)
stabilization of the frequency comb of a mode-locked laser
T. W. Hänsch et al., 1997, 1999H. Telle et al. Appl. Phys. B 69, 327 (1999)D. Jones et al., Science 288, 635 (2000)
Ne gasNe gas
few-femtosecond,few-cyclelaser pulse
λL 750 nmTp = 5 - 6 fsWp = 0.2 - 0.4 mJ
few-femtosecond,few-cyclelaser pulse
λL 750 nmTp = 5 - 6 fsWp = 0.2 - 0.4 mJ
Drescher et al., Science 291, 1923 (2001)
Hentschel et al., Nature 414, 509 (2001)
Kienberger et al., Science 297, 1144 (2002)
phase-stabilizedelectric fieldphase-stabilizedelectric field
xuv/x-ray radiation from strongly driven atoms
3D-solution of the Schrödinger equation for hydrogen: Armin Scrinzi (TU Vienna)
steering bound electrons with controlled light fields: the generation of a sub-femtosecond pulse
x(t)
EELL((tt))
EELL((tt))
EELL((tt))
EELL((tt))
xuv/x-ray radiation from strongly driven atoms
6060 7070 8080 9090 100100 11011000
10001000
Inte
ns
ity
[c
ou
nts
]In
ten
sit
y [
co
un
ts]
Photon energy [eV]Photon energy [eV]
xuv-filterxuv-filter
sub-femtosecond xuv/x-ray pulse generation
Ne gasNe gas
few-femtosecond,few-cyclelaser pulse
λL 750 nmTp = 5 - 7 fsWp = 0.3 - 0.5 mJ
few-femtosecond,few-cyclelaser pulse
λL 750 nmTp = 5 - 7 fsWp = 0.3 - 0.5 mJ
6060 7070 8080 9090 100100 11011000
10001000
Inte
ns
ity
[c
ou
nts
]In
ten
sit
y [
co
un
ts]
Photon energy [eV]Photon energy [eV]
time-of-lightelectron or ionspectrometer
time-of-lightelectron or ionspectrometer
atomicgas
atomicgas
near- diffraction-limitedxuv/soft-x-ray beamnear- diffraction-limitedxuv/soft-x-ray beam
xuv and laser pulse act on target particlesxuv and laser pulse
act on target particles
Drescher et al., Science 291, 1923 (2001)
Hentschel et al., Nature 414, 509 (2001)
Kienberger et al., Science 297, 1144 (2002)
attosecond pulse generation and detection
by irradiation with xuv-light pulses by irradiation with xuv-light pulses
core-levelphoto-
emission
+1
core-levelphoto-
emission
+1
Augerdecay
+2
Augerdecay
+2
photo-emission
&shake up
+1
photo-emission
&shake up
+1
Augerdecay
&shake up
+2
Augerdecay
&shake up
+2
kin.
ene
rgy
kin.
ene
rgy
00
core orbitalcore orbital
occupiedvalenceoccupiedvalence
unocc.valenceunocc.valence
triggering electronic transitions inside atoms
valencephoto-
emission
+1
valencephoto-
emission
+1final
charge statefinal
charge state
bind
. en
ergy
bind
. en
ergy
Exuv (t)
subsequentsubsequentcore-holecore-hole
by means of strong-field-induced free-free transitions: streaking by means of strong-field-induced free-free transitions: streaking
kin.
ene
rgy
kin.
ene
rgy
bind
. en
ergy
bind
. en
ergy core-level
photo-emission
+1
core-levelphoto-
emission
+1
Augerdecay
+2
Augerdecay
+2
photo-emission
&shake up
+1
photo-emission
&shake up
+1
Augerdecay
&shake up
+2
Augerdecay
&shake up
+2
00
occupiedvalenceoccupiedvalence
unocc.valenceunocc.valence
EL(t)
probing electronic transitions inside atoms
Exuv (t)
attosecondstreak camera
core orbitalcore orbital
valencephoto-
emission
+1
valencephoto-
emission
+1final
charge statefinal
charge state
resolution ~ 100 femtoseconds
electron-optical streak camera
D. J. Bradley et al., Opt. Commun. 2, 391 (1971)M. Y. Schelev et al., Appl. Phys. Lett. 18, 354 (1971)
eAL(t) eAL(t)
mapping time to momentum
electron release timeelectron release time
Δp(t7)Δp(t7)
Δp(t6)Δp(t6)
Δp(t5)Δp(t5)
Δp(t3)Δp(t3)
Δp(t2)Δp(t2)
Δp(t1)Δp(t1)
00
momentumchange alongthe EL vector
momentumchange alongthe EL vector
-500 as-500 as 00 500 as500 as
laser electric fieldlaser electric field
t7t7t1t1 t2t2 t3t3 t4t4 t5t5 t6t6
optical-field-driven streak camera optical-field-driven streak camera J. Itatani et al., Phys. Rev. Lett. 88, 173903 (2002)M. Kitzler et al., Phys. Rev. Lett. 88, 173904 (2002)
timetime
time-dependent
electron emission
time-dependent
electron emission
electronmomentumdistribution
electronmomentumdistribution
attosecond streak camera: complete measurement of a few-cycle light wave and a sub-fs xuv pulse
ele
ctr
on
co
un
ts /
bin
ele
ctr
on
co
un
ts /
bin
∆W(t) eAL(t)∆W(t) eAL(t)
6565
7575
8585
ele
ctr
on
kin
eti
c
en
erg
y [
eV
]
ele
ctr
on
kin
eti
c
en
erg
y [
eV
]
delay [fs]delay [fs]00 44-4-4 88
xuv pulsexuv
pulse
time [fs]time [fs]
inte
ns
ity
[a
rb.
u.]
inte
ns
ity
[a
rb.
u.]
00
11
ins
tan
tan
eo
us
e
ne
rgy
sh
ift
[eV
]in
sta
nta
ne
ou
s
en
erg
y s
hif
t [e
V]
9292
9393
9494
9595
9696
9797
-0.4-0.4 -0.2-0.2 0.00.0 0.20.2 -0.4-0.4
xuv = 250as
measurementsimulation
6060 7070 8080 9090 100100
final electron energy, Wf [eV]final electron energy, Wf [eV]
6060 7070 8080 9090 10010000
100100
6060 7070 8080 9090 100100
In the absenceof the laser field
single 250-attosecondxuv pulse @ 95 eV single 250-attosecondxuv pulse @ 95 eV
-6
6
3
0
-3
lig
ht
ele
ctr
ic f
ield
, E
L(t
) [1
07
V/c
m]
LL
( )( )
dA tE t
dt
-20-20
-10-10
00
1010
2020
v
ec
tor
po
ten
tia
l, -
AL(t
)
ve
cto
r p
ote
nti
al,
-A
L(t
) [f
sM
V/c
m]
[fs
MV
/cm
]
E. Goulielmakis et al., Science 305, (2004)
by means of strong-field-induced free-free transitions: streaking by means of strong-field-induced free-free transitions: streaking
kin.
ene
rgy
kin.
ene
rgy
bind
. en
ergy
bind
. en
ergy core-level
photo-emission
+1
core-levelphoto-
emission
+1
Augerdecay
+2
Augerdecay
+2
photo-emission
&shake up
+1
photo-emission
&shake up
+1
Augerdecay
&shake up
+2
Augerdecay
&shake up
+2
00
occupiedvalenceoccupiedvalence
unocc.valenceunocc.valence
EL(t)
probing electronic transitions inside atoms
attosecondstreaking spectroscopy
EXUV (t) core orbitalcore orbital
valencephoto-
emission
+1
valencephoto-
emission
+1final
charge statefinal
charge state
streaked electron spectra following core-hole excitation in krypton by a sub-fs xuv pulse
M. Drescher et al., Nature 419, 803 (2002)
tracing core-hole decay directly in time lifetime of M-shell (3d) vacancy in Krypton: h = 7.91 fs tracing core-hole decay directly in time lifetime of M-shell (3d) vacancy in Krypton: h = 7.91 fs
by means of strong-field-induced bound-free transitions: tunneling by means of strong-field-induced bound-free transitions: tunneling
kin.
ene
rgy
kin.
ene
rgy
bind
. en
ergy
bind
. en
ergy core-level
photo-emission
+1
core-levelphoto-
emission
+1
Augerdecay
+2
Augerdecay
+2
photo-emission
&shake up
+1
photo-emission
&shake up
+1
Augerdecay
&shake up
+2
Augerdecay
&shake up
+2
00
occupiedvalenceoccupiedvalence
unocc.valenceunocc.valence
EL(t)
probing electronic transitions inside atoms
EXUV (t) core orbitalcore orbital
valencephoto-
emission
+1
valencephoto-
emission
+1final
charge statefinal
charge state
attosecondtunneling spectroscopy
multiphoton versus tunneling ionization: the Keldysh theory
Keldysh, L.V., Sov. Phys. JETP 20, 1307 (1965)
multiphoton ionization: due to absorption of many photons
tunneling ionization: due to suppression of Coulomb potential
electron wave-packetsemitted within a time t shorter than the half-period of the laser
effective Coulomb barrier
tunneling
electron emission within a time mp shorter than the pulse duration
L
bL 2
eE
mW
Keldyshparameter:
> 1 < 1
time evolution of probing – ionization with a few-cycle pulse
atomic/molecular
target
bind
. en
ergy
bind
. en
ergy
occupiedvalenceoccupiedvalence
unocc.valenceunocc.valence
core orbitalcore orbital
kin.
ene
rgy
kin.
ene
rgy
level 1level 2
low E0high E0
level 2level 1
level 1
attosecond tunneling spectroscopy
first experiments in neon and xenon
testing the sub-fs resolution with neon
XUV pulse
NIR pulse
A. Kikas et al., J. of Electr. Spectr. and Rel. Phen. 77, 241-266 (1996).
95.2 % 4.8 %
92.8 % 7.2 %2.4 %
steps are visible -> sub-fs resolution is valid(signal/noise has to be improved)
2.4 %
Ne2+ versus delay time
..to be published
xenon energy levels – illustration of dynamics
XUV pulse
NIR pulse
8.9 %
78 %
3.3 %
9.7 %
Auger2Auger1
NIR-DI
NIR-I
Xe4+ versus time
Xe3+ versus time
A1 = 6.0 0.7 fs
A2 = 30.8 1.4 fs
A1
F. Penent et al., Phys. Rev. Lett. 95, 083002 (2005).
resolving electron dynamics in xenon
0 50 100 150 200 250
0
10
20
30
40
Delay time
Xe4+
Double exponential fit
Cou
nts
A1 = 6.0 0.7 fs
A2 = 30.8 1.4 fs
this experiment: time-integral frequency-resolved
experiments:
..to be published
F. Penent, Phys. Rev. Lett. 95, 083002 (2005).
A1 (4d3/2) = 6.3 0.2 fsA1 (4d5/2) = 5.9 0.2 fs
A2 > 23 fs
xuv optics & atomic spectroscopy:Th. Uphues, U. Kleineberg, U. Heinzmann
Univ. Bielefeld, Germany M. Drescher
Univ. Hamburg, DESY, Germanylight phase control:
Ch. Gole, R. Holzwarth, T. Udem, T. W. Hänsch Univ. Munich - MPQ Garching, Germany& measurement:
G. Paulus, H. Walther A&M Univ. Texas, USA / MPQ Garching Ch. Lemell, J. Burgdörfer, A. Scrinzi Vienna Univ. Techn., Austriametrology: P. B. Corkum, M. Yu. Ivanov NRC Canada, Ottawa, Canadamolecular spectroscopy: M. Kling, M. Vrakking AMOLF, Amsterdam, Netherlands M. Lezius, K. Kompa MPQ Garching, Germany
xuv optics & atomic spectroscopy:Th. Uphues, U. Kleineberg, U. Heinzmann
Univ. Bielefeld, Germany M. Drescher
Univ. Hamburg, DESY, Germanylight phase control:
Ch. Gole, R. Holzwarth, T. Udem, T. W. Hänsch Univ. Munich - MPQ Garching, Germany& measurement:
G. Paulus, H. Walther A&M Univ. Texas, USA / MPQ Garching Ch. Lemell, J. Burgdörfer, A. Scrinzi Vienna Univ. Techn., Austriametrology: P. B. Corkum, M. Yu. Ivanov NRC Canada, Ottawa, Canadamolecular spectroscopy: M. Kling, M. Vrakking AMOLF, Amsterdam, Netherlands M. Lezius, K. Kompa MPQ Garching, Germany
postdoctoral:
A. Apolonski
A. Baltuska
A. Cavalieri
T. Fuji
E. Goulielmakis
R. Kienberger
J. Seres
M. Uiberacker
V. Yakovlev
PhD candidates:
N. Ishii
T. Metzger
J. Rauschenberger
M. Schultze
C. Theisset
A. Verhoef
graphics: Barbara Ferus
postdoctoral:
A. Apolonski
A. Baltuska
A. Cavalieri
T. Fuji
E. Goulielmakis
R. Kienberger
J. Seres
M. Uiberacker
V. Yakovlev
PhD candidates:
N. Ishii
T. Metzger
J. Rauschenberger
M. Schultze
C. Theisset
A. Verhoef
graphics: Barbara Ferus
coworkers & collaborators
End
1 ionization of D2
2 recollisional excitation
3 formation of a coherent superposition (1sg
+,2pu+)
state in D2+
1 ionization of D2
2 recollisional excitation
3 formation of a coherent superposition (1sg
+,2pu+)
state in D2+
2pσu+2pσu+
may attosecond control of electronic motion in chemical bonds affect the outcome of molecular dynamics?
D+
rightright+D D
D+
leftleft + D D
YES: direction of emission of D+ is controlled by light waveform YES: direction of emission of D+ is controlled by light waveform
D2+D2+
1sσg+1sσg+
D2D2
e-e-
RR
1
23
time [fs]time [fs]
EL(t
)E
L(t
)
asy
mm
etry
lef
t/ri
gh
tas
ym
met
ry l
eft/
rig
ht
-5-5 00 55 1010 1515
0.50.5
00
-0.5-0.5
phase-controlledfew-cycle wave
M. Kling et al., Science 312, 246 (2006)
time
right
left
00
M. Kling et al., Science 312, 246 (2006)
time
right
left
M. Kling et al., Science 312, 246 (2006)