Advanced Plasma and Laser Science (Kenichi ISHIKAWA) for internal use only (Univ. of Tokyo)

Kenichi Ishikawa (石川顕一) http://ishiken.free.fr/english/lecture.html [email protected]

Advanced Plasma and Laser Science プラズマ・レーザー特論E

Attosecond Science (1) アト秒科学(1) 2014/5/20

1

Advanced Plasma and Laser Science (Kenichi ISHIKAWA) for internal use only (Univ. of Tokyo)

femtosecond, attosecond ミリ

m

10-3

マイクロ

μ

10-6

ナノ

n

10-9

ピコ

p

10-12

フェムト

f

10-15

アト

a

10-18

Light propagates during 30 fs …

3 × 108 (m/s) × 30 × 10−15 (s) = 9 × 10−6 (m) = 9 µm

2

2014/5/20

Advanced Plasma and Laser Science (Kenichi ISHIKAWA) for internal use only (Univ. of Tokyo)

Why so short pulses?

necessary shutter speed snapping ultrafast motion 3

for

2014/5/20

Advanced Plasma and Laser Science (Kenichi ISHIKAWA) for internal use only (Univ. of Tokyo)

Light=Electromagnetic wave

波長800nmの光の一周期 (optical cycle at 800 nm)

800

10

9

m/(3

108 m/s) = 2.7

10

15

s = 2.7 fs

First direct measurement of light waves 2004年！ 2014/5/20

4

Advanced Plasma and Laser Science (Kenichi ISHIKAWA) for internal use only (Univ. of Tokyo)

Attosecond science Electron

atomic unit of time = 24 attoseconds Orbital period of the Bohr electron Nucleus

2⇡ T = = 2⇡ !

r

2 e 1 mω 2 r = 4πϵ0 r2

4⇡✏0 mr3 = 152 as = 2⇡ a.u. 2 e

real-time observation and time-domain control of atomic-scale electron dynamics 2014/5/20

5

Advanced Plasma and Laser Science (Kenichi ISHIKAWA) for internal use only (Univ. of Tokyo)

‣

Dynamics of the Auger effect

‣

Delay in photoemission

‣

Direct measurement of light waves

2014/5/20

6

Advanced Plasma and Laser Science (Kenichi ISHIKAWA) for internal use only (Univ. of Tokyo)

Dynamics of the Auger effect オージェ効果のダイナミクス A method to analyze ultrafast processes with a laser field.

2014/5/20

7

Advanced Plasma and Laser Science (Kenichi ISHIKAWA) for internal use only (Univ. of Tokyo)

Auger effect オージェ効果 Photoelectron 光電子 Augerオージェ電子 electron 光電子 Photoelectron

Ejection of a core electron

内殻電子が電離（光電効果） Instantaneous Core-excited ion

内殻励起状態のイオン ~ a few fs Ejection of a valence electron

特性Ｘ線を放出するかわり に軌道電子を放出 Observation of the ejection of Auger electrons →Ionizing X rays < a few fs →Attosecond pulse 2014/5/20

8

Advanced Plasma and Laser Science (Kenichi ISHIKAWA) for internal use only (Univ. of Tokyo)

How to measure the electron ejection time?

Pump（イオン化を引き起 こす）

高調波(HHG)

Probe（電子の放出時刻を 測る）

レーザー光（laser）

2014/5/20

9

Advanced Plasma and Laser Science (Kenichi ISHIKAWA) for internal use only (Univ. of Tokyo)

How to measure the electron ejection time?

高調波とレーザー光を遅 延時間を持たせて照射 Irradiate an atom with an attosecond pulse and laser pulse with delay 2014/5/20

10

Advanced Plasma and Laser Science (Kenichi ISHIKAWA) for internal use only (Univ. of Tokyo)

How to measure the electron ejection time? E(t) = E0 (t) cos(ωt + φ)

dv dp =m = −eE(t) dt dt ionization at

t = tr で電離

Initial momentum 初速度（運動量）

! p0 = 2m(¯hωX − Ip )

p = p0 + ∆p ! ∞ " eE0 (t) sin(ωtr +φ) = 4mUp (tr ) sin(ωtr +φ) ∆p = −e E(t)dt = −eA(tr ) ≈ ω tr 検出器での運動量 Momentum at the detector

検出器での運動エネルギー Kinetic energy at the detector

p0 ∆p = W0 + W ≈ W0 + m

! 8W0 Up (tr ) sin(ωtr + φ)

2014/5/20

11

Advanced Plasma and Laser Science (Kenichi ISHIKAWA) for internal use only (Univ. of Tokyo)

How to measure the electron ejection time? 検出器での運動エネルギー

! W ≈ W0 + 8W0 Up (tr ) sin(ωtr + φ)

Electron kinetic energy

Ejection time 光電子のエネルギーと 遅延時間の関係

2014/5/20

12

Advanced Plasma and Laser Science (Kenichi ISHIKAWA) for internal use only (Univ. of Tokyo)

Life time of the Auger decay∼8 fs Auger effect 光電子 オージェ電子

Auger electron

光電子

Probe…Laser 750 nm

Photoelectron

Pump…HHG soft x rays 13 nm

10フェムト秒程度の超高速過程が見える！ Ultrafast process 10 fs 2014/5/20

13

Advanced Plasma and Laser Science (Kenichi ISHIKAWA) for internal use only (Univ. of Tokyo)

Delay in photoemission 光電効果には何アト秒かかるか？

2014/5/20

14

Advanced Plasma and Laser Science (Kenichi ISHIKAWA) for internal use only (Univ. of Tokyo)

When Does Photoemission Begin? The photoelectric effect is usually considered instantaneous.

e– Ne

Ne

+

∆t2s

2p

Ne 2s

Short light pulse

Ne

Ne+ ∆t2p e–

2014/5/20

15

rent experimental parameters, the small devia-

time for allowing us to track the history of

measure only re

that modeled via the CVA give rise to a 2-as discrepancy in the relative delay. Accepting this small discrepancy, manyelectron models were applied to investigate the effects of electron correlation. As a first attempt, the multiconfigurational Hartree-Fock method was used to evaluate transition matrix elements from the ground state of Ne to states where the electron wave asymptotically propagated along the direction of the streaking NIR electric field. These

calls for precise knowledge of the delay between the XUV pulse and an outgoing electron wave packet (henceforth, absolute delay). This can only be inferred from theory. For multielectron systems, such as Ne, physical description of the discrepancies revealed by this work proved to be a challenge. The sensitive experimental test to which time-dependent manyelectron models can now be subjected will benefit their development.

lute delays relies tested time-dep Presently, only tw provide this deg photoionization cause of low S/N complex system of the photoelect streaking will atomic photoion sensitive tests, w ually improving predictions. Thes understanding of and will make t atomic chronosco

Advanced Plasma and Lasertions Science ISHIKAWA) internal use only (Univ. photoemission c between the(Kenichi electron’s exact motion and for microscopic phenomena accurately (Fig.of 1A)Tokyo)

The 2s electron appears to come out 21 attoseconds earlier than the 2p electron!

References a 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

Fig. 3. The relative delay between photoemission from the 2p and 2s subshells of Ne atoms, induced by Schultze et al.,sub–200-as, Science 328, 1658 (2010) near–100-eV XUV pulses. The depicted delays are extracted from measured attosecond

streaking spectrograms by fitting a spectrogram, within the strong-field approximation, with parameterized NIR and XUV fields. Our optimization procedure matches the first derivatives along the time delay dimension of the measured and reconstructed spectrograms, thereby eliminating the influence of unstreaked background electrons [for details on the fitting algorithm, see (29)]. From the analysis of a set of spectrograms, the measured delays and associated retrieval uncertainties are plotted against the amplitude of the vector potential applied in the attosecond streak camera. Spectrograms measured in the presence of a satellite attosecond pulse were found to exhibit a less accurate retrieval of the delay value. When a subset of data (red diamonds) that represents scans with less than 3% satellite pulse content was evaluated, a mean delay value of 21 as with a standard deviation of ~5 as was found. The green circles represent the result of analyzing spectrograms recorded with an XUV pulse with narrower bandwidth in order to exclude the potential influence of shakeup states contributing to the electron kinetic energy spectrum.

Eisenbud‒Wigner‒Smith time delay Coulomb-laser coupling

laser-induced initial- and final-state distortion

2014/5/20

12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23.

H. Hertz, Annal W. Hallwachs, A A. Einstein, Ann E. P. Wigner, Ph C. A. A. de Carv 83 (2002). A. F. Starace, in (Springer, Berlin S. T. Manson, R M. Y. Ivanov, J. (2007). A. Baltuška et a R. Kienberger e M. Nisoli, G. Sa (2009). G. Sansone et a M. Schultze et a E. Goulielmakis M. Hentschel et A. Borisov, D. S Echenique, Che A. L. Cavalieri e A. K. Kazansky, 177401 (2009) C. Lemell, B. So A 79, 062901 ( J. C. Baggesen, 043602; and er U. Becker, D. A Photoionization (Plenum, New Y A. Rudenko et a J. Mauritsson et

16

Advanced Plasma and Laser Science (Kenichi ISHIKAWA) for internal use only (Univ. of Tokyo)

Direct measurement of light waves

2014/5/20

17

Advanced Plasma and Laser Science (Kenichi ISHIKAWA) for internal use only (Univ. of Tokyo)

Light is an electromagnetic wave

光は電磁波である

Maxwell

1864年 ∇ · D = ρ

∇·B=0 ∂B =0 ∇×E+ ∂t ∇×H=J …しかし、一体誰が光の電界が波 打つのを見たことがあるのか？ But who ever saw a light field oscillate?

2014/5/20

18

Advanced Plasma and Laser Science (Kenichi ISHIKAWA) for internal use only (Univ. of Tokyo)

Measurement of light fields by attosecond high-order harmonic pulses 電界による運動量変化

Momentum change

∆p = −e

!

∞

tr

E(t)dt = −eA(tr )

検出器での運動エネルギー Kinetic energy at the detector

! W ≈ W0 + 8W0 Up (tr ) sin(ωtr + φ)

2014/5/20

19

Advanced Plasma and Laser Science (Kenichi ISHIKAWA) for internal use only (Univ. of Tokyo)

Measurement of light fields by attosecond high-order harmonic pulses

光の電界の直接測定に初めて成功！→光が「電磁波」であるこ との直接的な証明 Direct proof of the wave nature of light E. Goulielmakis et al., Science 305, 1267 (2004).

2014/5/20

20