Photon Factory Activity Report 2014 #32(2015) B

BL-7A,11B/2013G683┤㙐࢔࡛ࣝ࢝ࣥಟ㣭ࡋࡓ㔠(111)㠃࡟࠾ࡅࡿࣃࣛࢪ࣒࢘ࢼࣀࢡࣛࢫࢱ࣮
Palladium Nanocluster on a Au(111) Surface Modified with n-Alkane㐲⸨ ⌮ 1*ࠊ୰ᮧ ᑗᚿ 2ࠊ㞵ᐑ ೺ኴ 3
ᮾி㎰ᕤᕤࠊࠛ184-8588 ᑠ㔠஭ᕷ୰⏫ 2-24-16
2༓ⴥ኱ᕤࠊࠛ263-8522 ༓ⴥᕷ✄ẟ༊ᘺ⏕⏫ 1-33
3
KEK-PFࠊࠛ305-0801 ࡘࡃࡤᕷ኱✑ 1-1
O. Endo1*, M. Nakamura2, K. Amemiya3
1

1

Department of Organic and Polymer Materials Chemistry, Faculty of Engineering,Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan2
Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Chiba University,Inage-ku, Chiba 263-8522, Japan3
Photon Factory, IMSS, KEK, Tsukuba, Ibaraki 305-0801, Japan
1 ࡣࡌࡵ࡟ᅛయ⾲㠃࡟࠾ࡅࡿ㔠ᒓᡂ㛗ࡣࠊపḟඖⓗ࡞ᵓ㐀ࡢసᡂᡭἲ࡜ࡋ࡚⯆࿡῝࠸ࠋ㔠(111)⾲㠃࡟྾╔ࡉࡏࡓ┤㙐࢔ࣝ࢝ࣥࡣศᏊ㛗㍈ࢆ⾲㠃࡟ᖹ⾜࡟ࡋ࡚࣓ࣛࣛ࡜࿧ࡤࢀࡿจ㞟ᵓ㐀࠿ࡽ࡞ࡿ༢ศᏊᒙࢆᙧᡂࡍࡿ[1]ࠋࡇࡢ༢ศᏊᒙࡢ␗᪉ⓗ࡞㓄ิᵓ㐀ࢆ฼⏝ࡋࡓ㔠ᒓࡢᡂ㛗ᵝᘧࡢไᚚࢆヨࡳࠊࣃࣛࢪ࣒࢘࠾ࡼࡧ㔠ࢆ⵨╔ࡋ࡚㉮ᰝࢺࣥࢿࣝ㢧ᚤ㙾ほᐹ(STM)ࢆ⾜ࡗࡓ࡜ࡇࢁࠊࣃࣛࢪ࣒࡛࢘ࡣ␗᪉ⓗ࡞ᡂ㛗ࡀほᐹࡉࢀࠊ㔠࡛ࡣ➼᪉ⓗ࡞ᡂ㛗ࡀほᐹࡉࢀࡓࠋᮏ◊✲ㄢ㢟࡛ࡣࡇࡢᡂ㛗ᵝᘧࡢ㐪࠸ࡢཎᅉࢆ᫂ࡽ࠿࡟ࡍࡿࡓࡵࠊⅣ⣲ K ྾཰➃㏆ഐ X ⥺྾཰ᚤ⣽ᵓ㐀ศග(C K-NEXAFS)࠾ࡼࡧ
ࣃࣛࢪ࣒࢘ L3 ➃ X ⥺྾཰ᚤ⣽ᵓ㐀ศග(Pd L3XANES) ᐃࢆ⾜ࡗࡓࠋ2 ᐇ㦂
C K-NEXAFS ᐃࡣ PF ࡢ BL-7A ࡛ MCP ᳨ฟჾࢆ⏝࠸ࡓ㒊ศ㟁Ꮚ཰㔞ἲ(㜼Ṇ㟁఩ 200 V)ࠊࡲࡓࡣ
SCIENTA ศගჾࢆ⏝࠸ࡓ࣮࢜ࢪ࢙㟁Ꮚ཰㔞ἲ(Ek =235-275 eV ࡢ㟁Ꮚࢆィᩘ)࡛ ᐃࡋࡓࠋ㠃ෆ᪉ྥࢆ୺࡟ほ ࡍࡿ┤ධᑕ(NI)࡜㠃┤᪉ྥࢆほ ࡍࡿᩳධᑕ(GI)᮲௳࡛⾜ࡗࡓࠋධᑕගࡢ࢚ࢿࣝࢠ࣮㍑ṇ࡟ࡣ
285.5 eV ࡟⌧ࢀࡿࢢࣛࣇ࢓࢖ࢺࡢ 1sЍπ*CC 㑄⛣(π*CC㑄⛣)ࢆ⏝࠸ࡓࠋPd L3-XANES ᐃࡣ BL-11B ࡛඲㟁Ꮚ཰㔞ἲ࡟ࡼࡾ ᐃࡋࠊࣃࣛࢪ࣒࢘⵨╔๓ࡢᇶᯈࡢࢫ࣌ࢡࢺࣝࢆࣂࢵࢡࢢࣛ࢘ࣥࢻ࡜ࡋࡓࠋ㔠(111)㠃
ࢆ኱Ẽ୰࡛ࣂ࣮ࢼ࣮࢔ࢽ࣮ࣝ࡟ࡼࡾΎί໬ࡋࠊ୙άᛶ㞺ᅖẼୗ࡛෭༷ࡋࡓᚋ n-C35H72 ࡲࡓࡣ n-C44H90 ࡢn-࣊࢟ࢧࣥ⁐ᾮ࡟ᾐࡋ࡚༢ศᏊᒙࢆᙧᡂࡉࡏࡓࠋヨᩱࢆ┿✵ᵴ࡬⛣㏦ࡋࠊ5x10-6 Pa ⛬ᗘࡢ㧗┿✵ୗ࡛ࣃࣛࢪ࣒࢘ࡲࡓࡣ㔠ࢆࢱࣥࢢࢫࢸࣥࣇ࢕࣓ࣛࣥࢺ࡟ᕳ
ࡁ௜ࡅࠊ㏻㟁ຍ⇕࡟ࡼࡗ࡚⵨╔ࡋࡓࠋ⵨╔㔞ࡣ᫬㛫࡛ไᚚࡋࡓࠋ
3 ⤖ᯝ࠾ࡼࡧ⪃ᐹ
ᅗ 1 ࡟ࣃࣛࢪ࣒࢘ࢆ⵨╔ࡋࡓ㝿ࡢ C K-NEXAFS ࢫ࣌ࢡࢺࣝ(a:NIࠊb:GI)ࢆ♧ࡍࠋ⵨╔๓ࡢ༢ศᏊᒙࡢࢫ

࣌ࢡࢺࣝ(㯮⥺)࡟࠾࠸࡚ NI ࡛ 292 eV ௜㏆࡟኱ࡁࡃ
ほ ࡉࢀࡿ྾཰ࣂࣥࢻࡣ σ*CC 㑄⛣࡟ᖐᒓࡉࢀࠊศᏊ
㍈ࡀ⾲㠃࡟ᖹ⾜࡛࠶ࡿࡇ࡜ࢆ♧ࡋ࡚࠾ࡾࠊSTM ࡛ほᐹࡉࢀࡿ࣓ࣛࣛᵓ㐀࡜ᑐᛂࡋ࡚࠸ࡿࠋ୍᪉ࠊ287 eV௜㏆ࡢࣂࣥࢻࡣ σ*CH/R(R ࡣ Rydberg ≧ែ)㑄⛣࡟ᖐᒓࡉࢀࡿࠋσ*CH/R 㑄⛣࡟ࡣⅣ⣲㦵᱁㠃࡟ᖹ⾜࡞㑄⛣(σ*CH/R||㑄⛣)࡜ᆶ┤࡞㑄⛣(σ*CH/R ԋ 㑄⛣)ࡀ࠶ࡾࠊࡑ
ࢀࡒࢀከᒙ⭷୰࡛ࡣ 287.6 eV ࡜ 288.2 eV ௜㏆࡟ほࡉࢀࡿ[2]ࠋ㔠ᒓ⾲㠃࡟Ⅳ⣲㦵᱁㠃ࢆᇶᯈ࡟ᖹ⾜࡟ࡋ࡚྾╔ࡍࡿ࡜(flat-on 㓄ྥ)ࠊ㑄⛣࣮࣓ࣔࣥࢺࡢ᪉ྥ
ࡀ CH ⤖ྜࡢ᪉ྥࢆྥࡃࡓࡵ NI ࡜ GI ୧೫ග࡛ほࡉࢀࡿࡼ࠺࡟࡞ࡾࠊCu(110)㠃࡛ࡣ 286.3 eV ࡜ 287.3eV ࡟྾཰ࡀ⌧ࢀࡿ[3]ࠋᅗ 1 ࡢࢫ࣌ࢡࢺ࡛ࣝࡣ 287eV ࡜ 288 eV ࡟ᑐᛂࡍࡿࣂࣥࢻࡀほ ࡉࢀࠊflat-on㓄ྥ࡛࠶ࡿࡇ࡜ࢆ♧ࡋ࡚࠸ࡿࠋࣃࣛࢪ࣒࢘ࢆ⵨╔ࡍ
ࡿ࡜ࠊGI ࡢࢫ࣌ࢡࢺ࡛ࣝ 285 eV ௜㏆ࡢ྾཰ࣂࣥࢻ
ࡀቑ኱ࡋࡓ(㉥ࠊ⥳⥺)ࠋࡇࡢࣂࣥࢻࡣ㔠ᒓ⾲㠃࡜
flat-on 㓄ྥࡢ CH ⤖ྜࡢ┦஫స⏝ࡢ⤖ᯝ⏕ࡌࡿ㑄⛣(M* 㑄⛣)࠿ࠊCC ୙㣬࿴⤖ྜࡢ⏕ᡂ࡟ࡼࡾ⏕ࡌࡿ
π*CC 㑄⛣࡟ᖐᒓࡉࢀࡿࠋDFT ィ⟬࡟ࡼࢀࡤ Pd(111)㠃
ࡢ᪉ࡀ Au(111)㠃ࡼࡾࡶ CH ࡜ࡢ┦஫స⏝ࡀ኱ࡁࡃࠊቑ኱ࡋࡓ M*㑄⛣ࡢᐤ୚ࡀᏑᅾࡍࡿྍ⬟ᛶࢆ♧ࡋ࡚࠸ࡿࠋ୍᪉ NI ࡛ほ ࡉࢀࡿ σ*CC 㑄⛣ࡢࣆ࣮ࢡ఩⨨ࡣ㧗࢚ࢿࣝࢠ࣮ࢩࣇࢺࡋ࡚࠾ࡾࠊCC ⤖ྜ㊥㞳ࡀ▷ࡃ࡞ࡗࡓࡇ࡜ࢆ♧၀ࡋ࡚࠸ࡿࠋࡇࡢࡇ࡜࠿ࡽ୙㣬࿴⤖ྜࡀ⏕ᡂࡋ࡚࠸ࡿ࡜⪃࠼ࡽࢀࡿࡢ࡛ࠊ285 eV ௜㏆
ࡢ྾཰࡟ࡣ π*CC 㑄⛣ࡢᐤ୚ࡀࡼࡾ኱ࡁ࠸࡜⪃࠼ࡽࢀࡿࠋࣃࣛࢪ࣒࢘ࡣ୙㣬࿴⤖ྜ࡬ࡢỈ⣲௜ຍࡢゐ፹࡜ࡋ࡚ࡼࡃ▱ࡽࢀ࡚࠸ࡿࡀ[4]ࠊ୙㣬࿴⤖ྜ࡜ࣃࣛࢪ࣒࢘࡟ᙉ࠸┦஫స⏝ࡀാࡃࡓࡵࠊ⬺Ỉ⣲཯ᛂಁ㐍ࡶྍ⬟࡛࠶ࡿ࡜᥎ ࡉࢀࡿࠋ⬺Ỉ⣲ᚋࠊࡇࡢᙉ࠸┦஫స⏝࡟ࡼࡾࣃࣛࢪ࣒࢘ࡀศᏊิ࡟ἢࡗ࡚㓄ิࡍࡿࡇ࡜ࡀ␗᪉ⓗ࡞ᡂ㛗ࡢ㉳※࡛࠶ࡿ࡜⪃࠼ࡽࢀࡿࠋ
ᅗ 2 ࡟㔠ࢆ⵨╔ࡋࡓ㝿ࡢ C K-NEXAFS ࢫ࣌ࢡࢺࣝࢆ♧ࡍࠋࣃࣛࢪ࣒࢘⵨╔᫬࡜ྠᵝࠊ⵨╔๓(㯮⥺)ࡣflat-on 㓄ྥࢆ཯ᫎࡋࡓࢫ࣌ࢡࢺ࡛ࣝ࠶ࡿࡀࠊ㔠⵨╔࡟ࡼࡗ࡚ GI ࡢ 285eV ௜㏆ࡢࣂࣥࢻࡣቑ኱ࡏࡎࠊNI

Photon Factory Activity Report 2014 #32 (2015) B㻌㻌Pd*ཧ⪃ᩥ⊩[1] H.-M. Zhang,et al.,Chem. Eur. J. 10(2004) 1415.
[2] O. Endo et al., J. Phys. Chem. C 117(2013) 21856.
[3] K. Weiss et al., J. Electron Spectrosc. Relat. Phenom.
128 (2003) 179.
[4] A. Valcárcel et al., J. Phys. Chem. B 109(2005) 14175.
[5] D. Zhong, et al.,Science 334(2011)213.
[6] O. Endo et al., e-J. Surf. Sci. Nanotech. 13 (2015) 209.
[7] M. W. Tew, et al., J. Phys. Chem. C 113(2009) 15140.
[8] O. Endo et al., PF Activity Report 2013 #31 (2014)
B,2011G629.
* oendo@cc.tuat.ac.jp

Pd1 ML*

M /S

0.1 ML㻌㻌

Absorption

0.1 ML*V CCNI*V CH/R*V CH/RGI

280 285 290 295 300 305 310 280 285 290 295 300 305 310

Photon Energy / eV

Photon Energy / eV

ᅗ 1: Pd/n-C44H90/Au(111)ࡢ C K-NEXAFS ࢫ࣌ࢡࢺࣝࠋ㻌㻌Au***Au

M /S1 ML*

M /S

1 ML

0.1 ML㻌㻌*V CC*V CH/R㻌

0.1 MLGINI*V CH/R

280 285 290 295 300 305 310 280 285 290 295 300 305 310
Photon Energy / eV
Photon Energy / eV

ᅗ 2: Au/n-C35H72/Au(111)ࡢ C K-NEXAFS ࢫ࣌ࢡࢺࣝࠋ
㻌

/ML

1.4

3.0

Absorption

1.0

㻌

0.7
0.3

0.2
0.1
Pd/Au(111)d-Hole Numberbulk
2.04 ࡲ࡜ࡵ
㔠(111)㠃࡟ᙧᡂࡋࡓ┤㙐࢔ࣝ࢝ࣥ༢ศᏊᒙ࡟ࣃࣛࢪ࣒࢘࠾ࡼࡧ㔠ࢆ⵨╔ࡋࡓ⣔ࡢ C K-NEXAFS ࢫ࣌ࢡࢺࣝࢆ ᐃࡋࡓࠋࣃࣛࢪ࣒࢘⵨╔࡟ࡼࡗ࡚⬺Ỉ⣲ࡀ㐍⾜ࡋࡓ⤖ᯝ⏕ࡌࡓ୙㣬࿴⤖ྜ࡜⵨╔ཎᏊ࡜ࡢ㛫ࡢᙉ࠸┦஫స⏝ࡀࠊ␗᪉ⓗ࡞ᡂ㛗ಁ㐍ࡢཎᅉ࡛࠶ࡿ࡜⪃࠼ࡽࢀࡿࠋ

*1 ML*M /SAbsorption

ࡢ σ*CC 㑄⛣ࡢࣆ࣮ࢡ఩⨨ࡶኚ໬ࡋ࡚࠸࡞࠸(㉥ࠊ⥳⥺)ࠋ㔠(111)㠃࡟࠾࠸࡚ n-࢔ࣝ࢝ࣥࡣ࠾ࡼࡑ 450 K
௨ୖࡢ ᗘ࡛ࡣ⬺Ỉ⣲཯ᛂࢆ㉳ࡇࡍࡀ[5]ࠊ௒ᅇࡣᐊ
ୗ࡛࠶ࡿࡇ࡜࠿ࡽ㉳ࡇࡽ࡞࠿ࡗࡓ࡜⪃࠼ࡽࢀࡿࠋ
ᅗ 3 ࡢ NI ࢫ࣌ࢡࢺࣝ(⥳⥺)࡟࠾࠸࡚ 288 eV ௜㏆ࡢ
σ*CH/Rԋ㑄⛣ࡢᙉᗘࡀቑ኱ࡋ࡚࠾ࡾࠊࡇࢀࡣ㔠⵨╔࡟ࡼࡾⅣ⣲㦵᱁㠃ࡀᇶᯈ࡟ᑐࡋ࡚ഴ࠸ࡓศᏊࡀฟ⌧ࡋࡓࡇ࡜ࢆ♧ࡋ࡚࠸ࡿࠋSTM ࡛ࡣ㔠ࢡࣛࢫࢱ࣮ࡢୗ࡟
࠾࠸࡚ࠊ࢔ࣝ࢝ࣥศᏊࡢ࣓ࣛࣛᵓ㐀ࡢ㓄ิࡀኚ໬ࡋ
ࡓ㡿ᇦࡀほᐹࡉࢀࡓ[6]ࠋ
ᅗ 3 ᕥ࡟ Pd/n-C44H90/Au(111)ࡢ Pd L3-XANES ࢫ࣌ࢡࢺࣝࢆ♧ࡍࠋL3 ➃ࡣ୺࡜ࡋ࡚ 2pЍ4d 㑄⛣ࢆほࡋ࡚࠸ࡿࡓࡵࠊ྾཰➃ࡢࣆ࣮ࢡᙉᗘ(white line ᙉᗘ)ࡣ d-hole ࡢᩘࢆ཯ᫎࡍࡿ[7]ࠋᅗ࠿ࡽࣂࣝࢡ࡟ẚ࡭࡚⵨╔ࣃࣛࢪ࣒࡛࢘ࡣ white line ᙉᗘࡀῶᑡࡋ࡚࠸ࡿ
ࡇ࡜ࡀศ࠿ࡿࠋࡇࢀࡣ༢ཎᏊཌ࡛ᩘ nm ࢧ࢖ࢬࡢࢡࣛࢫࢱ࣮࡜࡞ࡿࡇ࡜࡟ࡼࡗ࡚ࠊࣃࣛࢪ࣒࢘ࡢ㓄఩ᩘࡀῶᑡࡋࠊd ࣂࣥࢻࡢᖜࡀ⊃ࡃ࡞ࡾ༨᭷ᩘࡀୖ᪼ࡋࡓ⤖ᯝ࡜⪃࠼ࡽࢀࡿࠋWhite line ᙉᗘ࠿ࡽ௨๓࡜ྠ
ᵝࡢ᪉ἲ[8]࡛ぢ✚ࡶࡗࡓ d-hole ࡢᩘࢆᅗྑ࡟㯮ᅄゅ࡛♧ࡋࡓࠋ⿕そ⋡ 0.35 ML ࢆቃ࡟ d-hole ᩘࡀ୍ᐃ࡜
࡞ࡗ࡚࠸ࡿࡀࠊࡇࢀࡣ STM ࡛ほᐹࡉࢀࡓࢡࣛࢫࢱ࣮㛫ࡢ⼥ྜ㛤ጞ࡟ᑐᛂࡋ࡚࠸ࡿࠋ㉥୸ࡣ࢔ࣝ࢝ࣥᒙ
ࡢ࡞࠸㔠(111)㠃࡟⵨╔ࡋࡓࣃࣛࢪ࣒࢘ࡢ⤖ᯝ࡛࠶ࡿࠋ
࢔ࣝ࢝ࣥᒙ࡟ࡼࡗ࡚ྠࡌ⿕そ⋡࡟࠾࠸࡚ࡣ d-hole ࡢῶᑡᗘྜ࠸ࡀᑠࡉ࠸ഴྥ࡟࠶ࡿࠋࡇࢀࡣࠊ࢔ࣝ࢝ࣥ
ᒙᏑᅾ᫬ࡢ᪉ࡀࣃࣛࢪ࣒࢘ཎᏊࡢᣑᩓ㏿ᗘࡀ㏿ࡃࠊࢡࣛࢫࢱ࣮ࢧ࢖ࢬࡀ᪩ࡃᡂ㛗ࡍࡿࡓࡵ࡜ࠊPd-Au ྜ㔠໬࡟ࡼࡗ࡚ࡶ d-hole ᩘࡢῶᑡࡀࡳࡽࢀࡿࡇ࡜࡟ࡼࡿ࡜⪃࠼ࡽࢀࡿࠋ୍᪉ࠊỈ⣲࡜ࣃࣛࢪ࣒࢘ࡀ⤖ྜࡋࡓሙྜ࡟ white line ࠿ࡽ 5-10 eV ࡢ఩⨨࡟⌧ࢀࡿ࡜⪃࠼ࡽࢀࡿ Pd-H ཯⤖ྜ㌶㐨࡬ࡢ㑄⛣[7]ࡣほ ࡉࢀ࡚࠸࡞࠸ࡢ࡛ࠊỈ⣲ࡣ⬺㞳ࡋࡓ࡜⪃࠼ࡽࢀࡿࠋ

1.2

㻌

Pd bulk
1.27 0.36

0.40
0.35

1.1

0.30

0.9

0.25

0.7

0.1
1
coverage T / ML

0.20

3160 3170 3180 3190 3200
Photon Energy / eV

ᅗ 3: (ᕥ)Pd/n-C44H90/Au(111)ࡢ Pd L3-XANES ࢫ࣌ࢡࢺࣝࠋ(ྑ)white line ᙉᗘ࠿ࡽぢ✚ࡶࡗࡓ dhole ᩘࠋ