新学術領域「コンピューティクスによる物質デザイン：複合相関と非平衡ダイナミクス」
16/Mar/’12

金表面に吸着されたチオール単分子層のコヒーレント振動の実時間計測
Real-time Measurement of Coherent Molecular Motionof Benzenethiol Monolayer Film on Gold Surface
首藤健一a,*)、土井幸司郎a)、片山郁文a)、北島正弘b)、武田淳a)a) 横浜国大・工.
b) 防衛大・応物*) ken1@ynu.ac.jp1

新学術領域「コンピューティクスによる物質デザイン：複合相関と非平衡ダイナミクス」
16/Mar/’12

光誘起反応、光応答

Laser, SR; cw反射分光

シリサイド/シィケート形成

XPS, STS, STATE

STM誘起反応

STM, VASP

半導体上有機物

UPS, 2PPES, Gaussian

超高速応答

fs-laser

SH

測定方法
液相
表面吸着相
干渉・変調
2コヒーレント振動
(1)

(2)

Pump

Probe-光応答ProbeProbe

Probe(1) ポンプ光で格子振動を励起(2)格子変形によってプローブ光の反射率変化を検出
3光吸収率測定

4

Pump-probe

吸収率過渡応答

吸収率異方性E-O sampling5液層ベンゼンチオール(BT)
吸収過渡応答 (光透過計測)
Amplitude[arb.unit.]

Amlitude[arb.unit.]0

フーリエ変換0.8 1.0 1.2 1.4 1.6 1.8 2.0
Delay time[ps]

12

34

5

Delay time[ps]ElectronicResponse67

概ねラマンと対応----->振動
等方、非等方で強度が異なる
6

Organic Thin Films
Organic-molecular devices

Self-assembled monolayer- Discreet Electronic States-Response to External Fielde.g. Distortion by Gas
Photochromic Material- Easy to build- Orientation Preference- Interaction?

(1) Chem. Mater., 23 , 1061–1069 (2011).
(2) J. Am. Chem. Soc., 131, 865-870 (2009).

Coherent Motion by
Electronic Excitation

molecule-molecule
molecule-substrate

Ultrafast dynamics!
7Experimental
OpticsSamplePulsed Ti:Saphaire laser
EDuration : 7.5 fs
Wavelength : 800 nm
Pump-probe process
Probe
EO sampling for Surface

SpecimenAu deposition on Si(001)(Plasma sputter in vacuum)(1μ×1μ)

PD2

E⊥

E//
PumpPD1PBS

Benzenethiol (B.T.) on Au
Tiol: Typical SAM,
Benzene: Simplest Aromatic

Soaked into BT (in Me-OH)
c.f. Liquid BT (pure >98%)8

Adsorbed Benzenethiol on Au-film
Asymmetry in ReflectanceComparison of c.w.Raman-1

Modulated Envelope

0.6 0.8 1.0 1.2 1.4
Delay time[ps]012Electronic
Response

34

Delay time[ps]5Slower
Decay

67Fourie
Trans.

1600

Raman(532nm)
CoherentPhonon
Si SiO2

Intensity[arb.unit.]

Amplitude [arb.unit.]

Amplitude [arb.unit]

400

Raman shift[cm ]
800
1200

10No signal fromsubstrate

Detection Surface-sensitive to Monolayer
Molecular Motion in Real-times

203040Frequency[THz]50

Shifted from Liquid
9時間分解FFT-時間強度変化時間分解FFT
定常ラマン

実時間波形
25201510Intensity[arb.unit.]

Frequency[THz]Ampulitude[arb.unit.]

30502468Delay time[ps]1012000

52

各時間でHanning窓をかける

10 15 20 25 30
4681012Frequency[THz]
Delay time[ps]各時間でのFFT強度

0048
Delay time[ps]1234Intensity[arb.unit.]

Amplitude[arb.unit]

各時間窓でのFFT

120102030

10

Time-resolved Spectral Intensity
LiquidDelay time[ps]
2.0

10

1.0

3.0

4.0

5.0

Time-resolved FFTWindow:Hanning function
width 0.3ps

20

F.T. of whole signal

30

Frequency[THz]00.0Time-course of intensityof each component

20

Liquid vibrations
fluctuate in-phase30

10Frequency[THz]

0Adsorbed Layer

Different Modulation
11

Time-course of Intensity in Liquid
20THz
Intensity30THz
Intensity20THz

0.4ps
05
Frequency[THz]Frequencies in Beat

FourieTrans.

30THz
0.7

2.4

Intensity[arb.unit.]

1.31psSection at peakcomponents

2.70

1 2 3 4Frequency[THz]50

10

1 2 3 4Frequency[THz]Beat!
18.57THz
20.99THz

1520253035012
3
Delay time[ps]45Simple Beat: Sum of Close Modes -----> Independent Vibration

125

Time-course of Initial Phase in Liquid
Initial Phase φ in aSinusoidal Wave
LiquidFourier Component

E = Asin(ωt + φ )Hanning window: 0.8ps

0040

1520

20

020

Phase[rad]522 10Frequency[THz]Frequency[THz]24-2-418 25 -20
16 30

35-6-40

0 1

Phase 18.5THz
Phase 20.9THz

1 22 3
3 4
DelayDelaytime[ps]time[ps]

4551

2

3
Delay time[ps]4The two componts have constant φ.

Two modes vibrate independently.

13

Time-course of Initial Phase in Adsorbed Layer
Intensity of Adsorbed Layer
Section at peakcomponents
Intensity 30THz

FourieTrans.

00.5 0.7
1.2

2.2

1.6

05
Frequency[THz]Intensity[arb.unit.]

Frequencies in Beat

123
45
Frequency[THz]

1015
200.7
1.6

25

2.3

30
350

12
3
Delay time[ps]4514Interference is not simple summation of three componensts

6

Time-course of Initial Phase in Adsorbed Layer
1.0

2.0

3.0

4.0

5.030350.0

Intensity[arb.unit.]

Intensity of peaks in Adsorbed Layer

3Initial 1Phase 2 Delay time[ps]412Phase[rad]Frequency[THz]30031-10

29.96THz-232.28THz

1.5ps-4
30.71THz

32-20-6

3301

133
42 2
Delay time[ps]455Phase 29.96THz
Phase 30.71THz
Phase 32.28THz

1.5ps

010

4

Delay time[ps]

2829

3

1

2

3
Delay time[ps]4

Two modes has phase shift along time.
Interaction of the two out of the close three modes.
15

Surface vibronic modes in Adsorbed Layer
1011cm-1(30.33THz)

1033cm-1(30.99THz)

1087cm-1(32.61THz)

In-plane C-H rot.

Even memb

Odd memb.

Two Interactiong Modes: Expanding of Odd/Even Carbons
16
Due to Electronic? Or Configurationally?

Numerical Analysis
d 2 x1
C22()
ωxxx
=−+−
1
12
12mdt
d 2 x2
C22()
ωxxx
=−−−
222
12mdt

Initial Phase
33
32

40
30

020
1031

0010 0030

0-10-20

29

80.4%

19.6%

-30

28
0

12-40

3451003.580-12-15x10

2.5x101604020

ω1=30.71

2.00-20

1.526283032

1.034

Initial Phaseω1=30.00

3.00-1-2-30.5
10.0010203040

Frequency (THz)

5060234Frequency (THz)517Summary
ベンゼンチオール 超高速計測
Liquid-時間分解計測=フーリエ成分 → 振動
対称・非対称で強度比相違- 単分子吸着層= 反射配置：表面敏感計測= 重ね合わせ → ビート= 吸着層では位相変調→偶数・奇数変形で結合→ 非線形結合で説明

Adsorbed Layer
Mode Coupling

Sterice18