Advanced Laser and Photon Science (Takeshi SATO) for internal use only (Univ. of Tokyo)

Takeshi Sato (佐藤健) http://ishiken.free.fr/english/lecture.html [email protected]

Advanced Laser and Photon Science
 レーザー・光量子科学特論E





Attosecond Science (1)
 アト秒科学(1) 2018/6/19

1

Advanced Laser and Photon Science (Takeshi SATO) for internal use only (Univ. of Tokyo)

1. Brief review of high-field phenomena 2. Attosecond science

(within SFA, SEA, and CM,

6/26, 7/3, and 7/10: QM and multielectron description. Treated also in 量子ビーム発生工学特論E (Quantum Beam Generation Engineering))

(1)Attosecond pump-probe experiment (2)Direct measurement of light waves (3)Delay in photoemission (overview) (4)Auger dynamics (overview)

3. Ultrafast hole migration 2018/6/19

2

Advanced Laser and Photon Science (Takeshi SATO) for internal use only (Univ. of Tokyo)

femtosecond, attosecond ミリ

m

-3 10

マイクロ

μ

-6 10

ナノ

n

-9 10

ピコ

p

-12 10

フェムト

f

10-15

アト

a

10-18

3 2018/6/19

Advanced Laser and Photon Science (Takeshi SATO) for internal use only (Univ. of Tokyo)

Why so short pulses?

necessary shutter speed snapping ultrafast motion 4

for

2018/6/19

Advanced Laser and Photon Science (Takeshi SATO) 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 2 mω 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 2018/6/19

5

Advanced Laser and Photon Science (Takeshi SATO) for internal use only (Univ. of Tokyo)

1. Brief review of high-field phenomena 2. Attosecond science

(within SFA, SEA, and CM,

6/26, 7/3, and 7/11: QM and multielectron description)

(1)Attosecond pump-probe experiment (2)Direct measurement of light waves (3)Delay in photoemission (overview) (4)Auger dynamics (overview)

3. Ultrafast hole migration

2018/6/19

6

Advanced Laser and Photon Science (Takeshi SATO) for internal use only (Univ. of Tokyo)

2-1 Attosecond pump probe experiment Attosecond streaking Pump

Probe

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 Pump：イオン化を引き起こす induce ionization

高調波 = アト秒パルス HH = Attosecond pulse

Probe：電子の放出時刻を測る measure the electron ejection time

レーザー光 Laser

More generally Pump: induce something Probe: measure something, with delay 2018/6/19

7

Advanced Laser and Photon Science (Takeshi SATO) for internal use only (Univ. of Tokyo)

2-1 Attosecond pump probe experiment

高調波とレーザー光を遅延 時間を持たせて照射し、光 電子スペクトルを測定。 Irradiate an atom with an attosecond pulse and laser p u l s e w i t h d e l a y, a n d measure a photoelectron spectrum

Classical model E(t) = E0 (t) cos(ωt + φ)

Newton equation

dv dp =m = −eE(t) dt dt

ionization at Initial momentum

t = tr で電離 !

ニュートン方程式

p0 =初速度（運動量） 2m(¯hωX − Ip )

2018/6/19

8

Advanced Laser and Photon Science (Takeshi SATO) for internal use only (Univ. of Tokyo)

2-1 Attosecond pump probe experiment

高調波とレーザー光を遅延 時間を持たせて照射し、光 電子スペクトルを測定。 Irradiate an atom with an attosecond pulse and laser p u l s e w i t h d e l a y, a n d measure a photoelectron spectrum

Classical model

! p0 = 2m(¯ hω X − Ip )

Momentum at the detector 検出器での運動量： p = p0 + ∆p Z Z 1 E(t)dt p= e E(t)dt = eA(tr ) A(t) = tr

Kinetic energy at the detector

検出器での p0 p W ⇡ W0 + = W0 m 運動エネルギー：

p0 eA(tr ) m

p20 W0 = 2m 2018/6/19

9

Advanced Laser and Photon Science (Takeshi SATO) for internal use only (Univ. of Tokyo)

2-1 Attosecond pump probe experiment

高調波とレーザー光を遅延 時間を持たせて照射し、光 電子スペクトルを測定。 Irradiate an atom with an attosecond pulse and laser p u l s e w i t h d e l a y, a n d measure a photoelectron spectrum

Classical model Kinetic energy at the detector

p0 p W ⇡ W0 + = W0 m

Electron kinetic energy A(tr) at ejection time tr

p0 eA(tr ) m

p20 W0 = 2m

検出器での 運動エネルギー photoelectron energy vs. delay 光電子のエネルギーと 遅延時間の関係

2018/6/19

10

Advanced Laser and Photon Science (Takeshi SATO) for internal use only (Univ. of Tokyo)

1. Brief review of high-field phenomena 2. Attosecond science

(within SFA, SEA, and CM,

6/26, 7/3, and 7/11: QM and multielectron description)

(1)Attosecond pump-probe experiment (2)Direct measurement of light waves (3)Delay in photoemission (overview) (4)Auger dynamics (overview)

3. Ultrafast hole migration

2018/6/19

11

Advanced Laser and Photon Science (Takeshi SATO) for internal use only (Univ. of Tokyo)

2-2 Direct measurement of light waves 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?

2018/6/19

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Advanced Laser and Photon Science (Takeshi SATO) for internal use only (Univ. of Tokyo)

2-2 Direct measurement of light waves Measurement of light fields p W (tr ) ⇡ W0 + 8W0 Up sin(!tr + )

=)

E(t) = E0 cos(!t + )

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). 2018/6/19

13

Advanced Laser and Photon Science (Takeshi SATO) for internal use only (Univ. of Tokyo)

1. Brief review of high-field phenomena 2. Attosecond science

(within SFA, SEA, and CM,

6/26, 7/3, and 7/11: QM and multielectron description)

(1)Attosecond pump-probe experiment (2)Direct measurement of light waves (3)Delay in photoemission (overview) (4)Auger dynamics (overview)

3. Ultrafast hole migration

2018/6/19

14

Does Photoemission Begin?

2-3 Delay in photoemission

f photoemission was one s that led to the formuantum mechanics. If an bsorbs sufficient energy ght, it can transfer that on, which is then emittoemission mainly focus e temporal or dynamic —but complex electron that will create a slight absorption and electron e delay has been poorly undamental reason: We om absorbing a photon. ollow subsequent emisthem to establish a “time t was absorbed. A practieen that the time delay is d only recently have direct feasible with the advent pulses on the attosecond ale. On page 1658 of this and co-workers present me delays between differrocesses generated by the ht pulse. This finding not studies of the timing of lso provides a new way to interactions in atoms.

More in depth @ 6/26 (QM), 7/3,10 (Multielectron)

The complex dynamics of atomic photoemission has a simple origin—the emission of a negatively charged electron changes the neutral atom into a positive ion. The energy levels of the remaining electrons are different

in the positive ion, and as the electrons adjust to their new energy levels, they release energy that is transferred to the outgoing electron. The time needed for this transfer is the origin of the small time delays.

Downloaded from www.sciencemag.org o

Ultrafast spectroscopy and multielectron Advanced Laser and Photon Science (Takeshi SATO)electron for internal use only (Univ. of Tokyo) calculations reveal complex dynamics occurring just before an atom emits a photoelectron.

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

ic, Molecular, and Optical Physics, d Physics, Queen’s University BelE-mail: [email protected]

e– Ne

Ne+ ∆t2s

2p

Ne 2s

Short light pulse

Ne

Ne+ ∆t2p e–

Electron hesitation. Schematic diagram of a photoemission process for Ne. An incoming photon of an ultrashort light pulse is absorbed by either a 2s (top row) or a 2p (bottom row) electron. After photoabsorption, the electron escapes, while the orbitals of the other electrons adjust to the new surroundings as the atom becomes an ion. This adjustment leads to a time delay ∆t in the emission of the electron, which is longer for emission of a 2p electron than for emission of a 2s electron.

2018/6/19

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known analytical approaches. Thus, for the cur-

mentally. Precise determination of the zero of

attosecond

nucleus. Further- parameters, the measured delay of ~20 as cannot be explained distance of less than 1 Å from the function cðeÞ describes properties of rent experimental thefully small devia- thetime for allowing us to track the history of measure o Advanced Laser and Photon Science (Takeshi SATO) for internal use only (Univ. of Tokyo) role, the by a delayed onset of streaking, which was the more, if screening played a dominant the wave packet. In this representation, a delay Dt tions between the electron’s exact motion and microscopic phenomena accurately (Fig. 1A) photoemis dominant effect in (17). The streaking NIR faster 2p electrons would be exposed to the in photoemission, shown as a shift of the electhat modeled via the CVA give rise to a 2-as calls for precise knowledge of the delay be- lute delays field may be significantly screened by bound streaking field earlier than the slower 2s ones, tron’s trajectory in Fig. 1B, adds eℏ Dt to the phase discrepancy in the relative delay. tween the XUV pulse and an outgoing electron tested tim electrons at small distances from the nucleus. whereas measurements and quantum simulations of cðeÞ. It is therefore meaningful to define the Accepting small delay discrepancy, manywave packet first. this group After the absorption of an XUV photon, it takes show that the slower electron is emitted of the outgoing electron wave pack-(henceforth, absolute delay). This Presently, models were to investigate theworkcan Now we turn our attentionelectron to the quantumthe positive-energy electron a finite time to leave et,applied in accordance with earlier (4, only 5, 25),beas inferred from theory. For multi- provide th d of electron a first attempt, systems, such as Ne, physical descrip- photoioniz of all, we need a correlation. this screened volume, and this time interval may mechanical description. First effects aðeÞ ¼ ℏ deAs arg½cðeÞ%. Analyzingelectron our simulathe multiconfigurational Hartree-Fock method was tion of the revealed by this work cause of lo be different for electrons originating from dif- definition for the photoemission delay. Consider tions, we average aðeÞover the bandwidth discrepancies of to created evaluate matrix proved jyðtÞ〉 bytransition ferent orbitals. However, for an atom, this dif- a photoelectron wave functionused the XUV pulseelements (29) andfrom denote the resulttoasbe a. a challenge. The sensitive exper- complex s stateofof Ne toAs states where electron 0. ground The motion ference cannot exceed a few attoseconds. The an XUV pulse centered at t ¼the the first andthe most importantimental task, wetest val-to which time-dependent many- of the pho is conve- idate characteristic scales can be extracted from the the wave packet after photoionization the experimental Intuitively, wave asymptotically propagated along the methodology. direc- electron models can now be subjected will benefit streaking continuum states one classical trajectories shown in Fig. 1B. If we as- niently described in a basis oftion expects thatfield. a delay in the formation of a atomic pho of the streaking NIR electric These their development. sume that the 2s and 2p electrons are set in je〉, each of which has a well-defined energy e wave packet causes a corresponding temporal sensitive t motion at the same moment, their classical and describes a wave that propagates in the di- shift of the streaking spectrogram. This holds true ually impr

2-3 Delay in photoemission

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

=)

W (tr ) = W0

Downloaded from www.sciencemag.org on June 21, 2011

E(t), A(t) : known(controlled)

p0 eA(tr ) m

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. 2018/6/19

Eisenbud‒Wigner‒Smith time delay Coulomb-laser coupling

laser-induced initial- and final-state distortion

predictions understand and will m atomic chr

Refere 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23.

H. Hertz W. Hall A. Einst E. P. W C. A. A. 83 (200 A. F. St (Springe S. T. Ma M. Y. Iv (2007). A. Baltu R. Kienb M. Niso (2009). G. Sans M. Schu E. Gouli M. Hent A. Boris Echeniq A. L. Ca A. K. Ka 177401 C. Leme A 79, 0 J. C. Ba 043602 U. Beck Photoio (Plenum A. Rude J. Mauri

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Advanced Laser and Photon Science (Takeshi SATO) for internal use only (Univ. of Tokyo)

2-4 Auger dynamics

More in depth @ 7/3, 10 (Multielectron)

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

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 2018/6/19

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Advanced Laser and Photon Science (Takeshi SATO) for internal use only (Univ. of Tokyo)

2-4 Auger dynamics

Auger effect Photoelectron 光電子

Auger electron

Auger electron オージェ電子 Photoelectron 光電子

Probe…Laser 750 nm

Pump… HHG soft x ray 13 nm Photoelectron

10フェムト秒程度の超高速過程が見える！ Ultrafast process 10 fs 2018/6/19

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Advanced Laser and Photon Science (Takeshi SATO) for internal use only (Univ. of Tokyo)

1. Brief review of high-field phenomena 2. Attosecond science

(within SFA, SEA, and CM,

6/26, 7/3, and 7/10: QM and multielectron description)

(1)Attosecond pump-probe experiment (2)Direct measurement of light waves (3)Delay in photoemission (overview) (4)Auger dynamics (overview)

3. Ultrafast hole migration

2018/6/19

19

ignature of ultrafast e molecule (14). econd techniques to bility of investigating es, which involve elecof freedom and their ge molecules (e.g., biules), prompt ioniza-

. most

lanine.

packet created by the attosecond pulse strongly and Photon Science (Takeshi SATO) for internal use only (Univ. of Tokyo) support the Advanced interpretation Laser of the experimental data in terms of charge migration resulting from ultrafast electron dynamics preceding nuclear rearrangement. The a-amino acids consist a central carbonon 7/3, 10 (Multielectron) May beofrevisited atom (a carbon) linked to an amine (-NH2) group, a carboxylic group (-COOH), a hydrogen

3. Ultrafast hole migration

N

O

heres, e, xygen. s nsity a

pump sub-300 as XUV 15-35 eV probe 4 fs VIS/NIR 1.77 eV / 700 nm detect ++NH2-CH-R dication

sciencemag.org SCIENCE

2018/6/19

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only the be related to nuclear which scale. The experimental display a rise time of Advanceddata Laser and Photon Science (Takeshi SATO) dynamics, for internal use usually only (Univ.430 of K, Tokyo) substantially pr come into play on a longer temporal scale, ulti10 T 2 fs and an exponential decay with time mentary materi mately leading to charge localization in a parconstant of 25 T 2 fs [this longer relaxation time figuration show ticular molecular fragment. Indeed, standard constant is in agreement with earlier experiTo further inv we also varied width of the att an indium foil XUV spectrum width at half m 15 eV, followed component ext doubly charged ly visible, sugge involves relativ cation. We have gram with all th alanine generat all the states of materials). A nu states of the ca dication are po tion of just a fe cannot be acces in the case of X dium foil. In th states to the low the less probab photons. We also perfo describe the ho Fig. 2. Pump-probe measurements. (A) Yield of doubly charged immonium ion (mass/charge = 60) as second pulse si a function of pump-probe delay, measured with 3-fs temporal steps.The red line is a fitting curve with an ment. Details o exponential rise time of 10 fs and an exponential relaxation time of 25 fs. (B) Yield of doubly charged supplementary immonium ion versus pump-probe delay measured with 0.5-fs temporal steps, within the temporal central frequen 21 2018/6/19 window shown as dotted box in (A). Error bars show the standard error of the results of four measurethe pulse, a ma

3. Ultrafast hole migration

dication yield oscillates with period

4.3 fs

assigned to electron dynamics in the molecule

Advanced Laser and Photon Science (Takeshi SATO) for internal use only (Univ. of Tokyo)

3. Ultrafast hole migration

Time evolution of hole density (calculation) 正孔密度の時間発展 Why does hole migrate ? detected Create wave packet 波束の生成

Energy levels of relevant species エネルギーレベル probe: 1.77 eV / 700 nm 4 fs VIS/NIR pump: 15-35 eV sub-300 as XUV

2018/6/19

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