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@G< i]:4RS7>m ¡>¢<hc£¤> ¥HQ<j¦v§klvH]¨©>i R4N+ :4RS7:RSªsZ«©¬­®¯5°±(SEIRAS)ZG<hj¨©vH]²Z³´mi¦7v¨©: R4N+:µ¶7U{$«©·>?@¸Z³´v¹ij¦¦vH]CO º»gC4B«©>]C4BU{¼½DEFGmi¾v>]·>;i4:RS¿:ÀÁ>ªsmiÂZ]A4BU{:Ã7ÄÅgj1ÆÇ3, Si-ATR ÈÉÊ~:^Ë©>ÌÍOzvFg Pt ÎÏZFG7ghG<]²ªs>ÐÁ¨©56:ªsZ SEIRAS vÑÒgj¾]Pt «©> CO Zº»ÓÔhÕ²vÖ×QC4«©ZØgjÙÚ>H Ag/AgCl(KCl sat.)ZÛGgj1Ã7ÜÒ3, CO º»g Pt «©> 0.02 M ÝÞMwxÈßàpy{n|}~!Pr4NP(qr:áv®¯ºâKãPwpZä×g
[1]j²Z 200 Â-1000 mV >åæmi7]
Pr4N+U{: C-H ªçèé>êëÓ i
ì{í 1487, 1465, 1388 cm-1 >d ¬îgj¦ H]«©Õ>ïmi7q
rð>ñò{óôg]õö÷Zmi>Dømij¦:ù]O-H úû
èéüý:ªsZþi7]200 Â-300 mV:üývH 3477 7 3357 cm-1 >4gì{í¬îgj¦:4ì{íFig. 1 IR spectra of a CO-covered Pt electrode in 0.02 M tetra-propyl:¬îH]Pr4N+:¬î7@ÿ_g]ammonium perchlorate, measured during a potential sweep at 5 mV s . (a)-1High and (b) low frequency regions. The inset shows the spectrum¦ H]Pr4N+:IJ:4:RSZ^ g] measured at -400 mV and the curve fitting results by the Gaussianfunction. (c) Red and blue plots show the integrated band intensities of-1-1
ìpP:4ÀJ!]ÀJRSsÓ h<i !(CH) (1500~1430 cm ) and "(O-H) (3750~2800 cm ), respectively. (d)Comparison of the spectral lineshape of on-top CO measured at 250, -150,-600, and -1000 mV. Peak top position and intensity were normalized.
¦7"Â#j, ²Z-300 mV $%>mi7]Pr4N+:¨©µ¶Hæ¹

isolated OH&¹'(mi>!ÂÂ")]4>êëÓ iõ¢

H-bonded OH-900mV:ì{í7]C4«©>½g4(CO ':4)>êëÓ

-100Na+-1i 3670 cm :ì{í[2]:­¶*+gj¦ H]

#Abs = 0.002(a)-900mV,­¶­@Qi7U{«©>æ¹¢ i¸
­@Qi]«©7:DEFG>ÀJ4-.Ó

-100

Mg2+(b)¦7Z/gh<ij¾]4-.Ó i²-700mVüývH]CO :KãPwp:0ÿ1B¬îmi2Zn2+(c)-100

6ÑÒÓ j-800, 3>]A4B:4ëñò{v!2QÆÇZ5#j-900

0.1 M NaClO4 ráv CO º»g Pt :²Z0 Â-1000 mV ¾vå6gQ SEIRA KãPwpZä-300 mV-1H+×mi7 3600 cm >7g<ì{íd ¬îg!Fig. 2a(]

(d)

200

3670 cm-1 :ì{í8>*+g!Fig. 3(jÕ²v-900mV-1H¨©:ñò{µ¶¬îmi]3670 cm :*+Et4N+(e)-100H]4gñò{¨©>½9g]CO ':456-500mV-1Z:<;g¦7Z/gh<ij¾]3600 cm :ì{Pr4N+íH]ñò{>f²g]Â¢ CO 7DEFGg4>-100mVêëÓ ij-900, 2QÃH Mg2+` Zn2+v!< ]A4¤Q4ëU
{½9mi7 CO ':4=>>?g: ]7g<ì{í:4;dmi¦75Â#jCO '>@i456[\i 3670 cm-1 :­¶ªs:
²ABBZ¾7: Fig. 3 v;ijA4¤Q4ëU

(f)-9003800

3600
3400
3200
Wavenumber / cm-1

3000Fig. 2 Potential dependent SEIRA spectra of water ona CO-covered Pt electrode in 0.1 M NaClO4,Mg(ClO4)2, Zn(ClO4)2, HClO4, tetraethylammonuim
perchlorate(Et4NP),
and0.02
M
tetrapropylammonium perchlorate (Pr4NP). Eachreference spectrum was measured at 0 V.

{:,>H 0 V Â-1000 mV ¾v8>*+mi]
N+C4B: Pr4N+:,>H]-400 mV ¾vC7D¿ªsÔN+)]:EFG>*+mi¦7À@5Âij¦:ÃOCH]õ¢:C4B894Z?g:h¼½DEFGmg]:EFG>*+mijEt4N+HA4B7C4B:á
·¤QB9ZM#h<i¦7N h<ij

©456:RSªs>mXY>¢<hWXmij[1] A. Yamakata and M. Osawa J. Am. Chem. Soc. 131 (2009) 6892.
[2] Q. Du, R. Superfine, E. Freysz, Y.R. Shen, Phys. Rev. Lett. 70 (1993)
2313.

OCOCOCPr 4N+-2-4C4BU{7A4BU{vH]OP4Q>;i456:fRSQijTUvH]¦:fR:V<¨O
C

Et 4N+

electrostatic force

h<ijEt4N+:,>H]0~-400 mV ¾vL`Â>*+OC0#AbsorbanceiH>]4ZID=Ö×QRSBJmi¦7Z/Kg

OC

removedO O OCCC

Mg 2+M+OCOCremoved
O O OCCCOC

Na +Zn 2+0-200 -400 -600 -800
Potential / V vs Ag/AgCl-1000

Fig. 3 Potential dependence of the peak intensity ofthe free OH at ~3670 cm-1 on CO-covered Pt electrodeduring the negative potential sweep. The insets show
schematic representations of the interfacial water
structure and hydration shells around hydrophilic andhydrophobic cations.