An in situ scanning tunneling microscopy and cyclic voltammetric study of iodobenzene and iodoheptane molecules adsorbed on a Pt(111) electrode

被引:10
作者
Chen, JH
Yau, SL [1 ]
Chang, SC
机构
[1] Natl Cent Univ, Dept Chem, Chungli 320, Taiwan
[2] Helix Corp, Hsinchu 300, Taiwan
关键词
D O I
10.1021/jp020236k
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
We employed in situ scanning tunneling microscopy (STM) and cyclic voltammetry to study the adsorption of iodobenzene and iodoheptane molecules onto a well-ordered Pt(111) electrode in 0.1 M HClO4. These molecules were adsorbed intact without noticeable decomposition at potentials negative of 0.9 V (vs a reversible hydrogen electrode), whereas degradation became prominent at potentials positive of 0.9 V. The coverage of the iodobenzene monolayer is estimated to be about 0.45 from the amount of charges involved in its reductive desorption in KClO4 (pH 10) solutions. This value nearly equals that of iodine atoms at Pt(111). In situ STM was used to probe the spatial arrangements of these adsorbates as a function of potential in 0.1 M HClO4.A well-packed (root7 x root7)R19.1degrees-iodobenzene structure predominated at 0.3 V, which readily rearranged into a (3 x 3) adlattice as a result of a slight increase of coverage at more positive potentials. The. STM appearances of these two adlattices resemble those of iodine atoms on Pt(111), suggesting that the contrast in STM arises mainly from the iodine headgroups. More negative potentials resulted in desorption of iodobenzene molecules and a disordered adlayer. In contrast, iodoheptane molecules were disordered at potentials negative of 0.7 V, but reorganization occurred to produce local (root7 x root7)R19.1degrees at more positive potentials. These, phase transitions were reversible to the modulation of potential between 0 and 0.9 V. The electrochemical potential dominated not only the chemical nature but also the spatial arrangements of the alkyl or, aryl iodide molecules. The tip-and-sample interaction was noticeably stronger for iodoheptane, resulting in disordering of the adlayer.
引用
收藏
页码:9079 / 9085
页数:7
相关论文
共 36 条
[1]   7X7 RECONSTRUCTION ON SI(111) RESOLVED IN REAL SPACE [J].
BINNIG, G ;
ROHRER, H ;
GERBER, C ;
WEIBEL, E .
PHYSICAL REVIEW LETTERS, 1983, 50 (02) :120-123
[2]   The thermal chemistry of iodobenzene on Pt(111) [J].
Cabibil, H ;
Ihm, H ;
White, JM .
SURFACE SCIENCE, 2000, 447 (1-3) :91-104
[3]   ELECTROCHEMISTRY AT PLATINUM SINGLE-CRYSTAL SURFACES IN ACIDIC MEDIA - HYDROGEN AND OXYGEN-ADSORPTION [J].
CLAVILIER, J ;
RODES, A ;
ELACHI, K ;
ZAMAKHCHARI, MA .
JOURNAL DE CHIMIE PHYSIQUE ET DE PHYSICO-CHIMIE BIOLOGIQUE, 1991, 88 (7-8) :1291-1337
[4]   Scanning tunneling microscopy observations of butanethiol self-assembled monolayers on Ag underpotential deposition modified Au(111) [J].
Hsieh, MH ;
Chen, CH .
LANGMUIR, 2000, 16 (04) :1729-1733
[5]   ELECTROCHEMISTRY AT WELL-CHARACTERIZED SURFACES [J].
HUBBARD, AT .
CHEMICAL REVIEWS, 1988, 88 (04) :633-656
[6]   Underpotential deposition of copper on iodine-modified Pt(111): In situ STM and ex situ LEED studies [J].
Inukai, J ;
Osawa, Y ;
Wakisaka, M ;
Sashikata, K ;
Kim, YG ;
Itaya, K .
JOURNAL OF PHYSICAL CHEMISTRY B, 1998, 102 (18) :3498-3505
[7]   In situ scanning tunneling microscopy in electrolyte solutions [J].
Itaya, K .
PROGRESS IN SURFACE SCIENCE, 1998, 58 (03) :121-247
[8]   Iodobenzene on Pd(111) studied by thermal desorption spectroscopy and laser-induced thermal desorption-Fourier transform mass spectrometry [J].
Jaramillo, DM ;
Hunka, DE ;
Land, DP .
SURFACE SCIENCE, 2000, 445 (01) :23-31
[9]   CHARACTERIZATION OF ADSORPTION STATES OF ATOMIC IODINE ON PT(111) [J].
JO, SK ;
WHITE, JM .
SURFACE SCIENCE, 1992, 261 (1-3) :111-117
[10]   VACUUM TUNNELING CURRENT FROM AN ADSORBED ATOM [J].
LANG, ND .
PHYSICAL REVIEW LETTERS, 1985, 55 (02) :230-233