메뉴 건너뛰기




Volumn 19, Issue 20, 2003, Pages 8245-8255

Self-assembled oligo(phenylene-ethynylene) molecular electronic switch monolayers on gold: Structures and chemical stability

Author keywords

[No Author keywords available]

Indexed keywords

COMPOSITION EFFECTS; CRYSTAL LATTICES; ELECTRONIC STRUCTURE; ELLIPSOMETRY; GOLD; HYDROLYSIS; INFRARED SPECTROSCOPY; MOLECULAR STRUCTURE; MONOLAYERS; SELF ASSEMBLY; X RAY PHOTOELECTRON SPECTROSCOPY;

EID: 0141888178     PISSN: 07437463     EISSN: None     Source Type: Journal    
DOI: 10.1021/la035172z     Document Type: Article
Times cited : (143)

References (107)
  • 41
    • 0345979435 scopus 로고    scopus 로고
    • Ulman, A. Chem. Rev. 1996, 96, 1533-1554.
    • (1996) Chem. Rev. , vol.96 , pp. 1533-1554
    • Ulman, A.1
  • 74
    • 0002784623 scopus 로고
    • The photochemistry of nitro and nitroso groups
    • Feuer, H., Ed.; Interscience: New York
    • Morrison, H. A. The photochemistry of nitro and nitroso groups. In Chemistry of the Nitro and Nitroso Groups; Feuer, H., Ed.; Interscience: New York, 1969; pp 165-214.
    • (1969) Chemistry of the Nitro and Nitroso Groups , pp. 165-214
    • Morrison, H.A.1
  • 77
    • 0141948086 scopus 로고
    • Effects of optical anisotropy on spectro-ellipsometric data for thin films and surfaces
    • Francombe, M., Ed.; Physics of Thin Films Series; Academic Press: New York
    • Parikh, A. N.; Allara, D. L. Effects of Optical Anisotropy on Spectro-Ellipsometric Data for Thin Films and Surfaces. In Optical Studies on Real Surfaces and Inhomogeneous Thin Films; Francombe, M., Ed.; Physics of Thin Films Series; Academic Press: New York, 1994; Vol. 19, pp 279-323.
    • (1994) Optical Studies on Real Surfaces and Inhomogeneous Thin Films , vol.19 , pp. 279-323
    • Parikh, A.N.1    Allara, D.L.2
  • 78
    • 0141982662 scopus 로고    scopus 로고
    • note
    • Previous spectroscopic ellipsometry studies have shown the presence of a weakly metallic Au-S interface layer of ∼0.2 nm thickness (ref 76). Experiments are currently inprogress in our laboratory to characterize the properties of the interface layers for the current SAMs.
  • 94
    • 0141913677 scopus 로고    scopus 로고
    • note
    • sample is the thickness of the sample and was the value of interest.
  • 97
    • 0141913675 scopus 로고    scopus 로고
    • note
    • A conclusion interpretation of the OPE CVs is complicated by the fact that they exhibit characteristics indicative of neither a completely blocking film nor a film whose electrochemical response is dominated by well-separated pinholes. The CV is further complicated by the fact that tunneling through the OPE monolayers is more efficient than through alkyl chains [e.g., see ref 18]. If the OPE CVs were characteristic of a film containing many pinholes separated by a distance greater than 10 times the radius of the individual pinhole, there would be no defined reduction-oxidation peaks nor hysteresis in the sweeps [Wightman, R. M.; Wipf, D. O. In Electroanalytical Chemistry; Bard, A. J., Ed.; Marcel Dekker: New York, 1989; Vol. 15, Chapter 3]. The CV would be sigmoidal in shape, and the reduction-oxidation currents would reach a steady state due to the limitations of mass transfer present at pinholes or microelectrodes. The increased peak splitting and the reduced peak currents of the OPE CVs compared to the bare Au are indicative of Faradaic processes that are dictated in part by pinholes and packing defects and by depletion of redox species by tunneling through the SAM-covered areas on the electrode.
  • 98
    • 0003979716 scopus 로고
    • John Wiley & Sons: New York; note
    • Varsanyi, G. Assignments for Vibrational Spectra of Seven Hundred Benzene Derivatives; John Wiley & Sons: New York, 1974. Varsanyi classified benzene derivatives according to the number and approximate mass of the attached substituents. The carbon and nitrogen substituents are considered "light", while a sulfur is considered "heavy".
    • (1974) Assignments for Vibrational Spectra of Seven Hundred Benzene Derivatives
    • Varsanyi, G.1
  • 99
    • 0141948088 scopus 로고    scopus 로고
    • note
    • -1 in the monolayer spectra of both 1 and 2 was excluded from the analysis because it is composed of component modes with different dipole directions and the components could not be sufficiently resolved.
  • 101
    • 0141948089 scopus 로고    scopus 로고
    • note
    • While the SWE and XPS thickness values ranging from ∼1.81-1.94 nm are larger than the IRS tilt angle determined values of 1.51-1.65 nm, one must be careful when assigning accurate values since all the methods have inherent errors. For example, in determining the SWE values the presence of a S-Au interface layer and the optical anisotropy of the molecules were neglected while in the XPS analysis the photoelectron escape depth in the aromatic SAM was estimated from data on aliphatic SAMs.
  • 102
    • 0035822862 scopus 로고    scopus 로고
    • note
    • 2 group of one molecule and an adjacent aromatic ring: Taylor, J.; Brandybyge, M.; Stokbro, K. (http://arxiv.org/PS_cache/cond-mat/pdf/0212/0212191.pdf)]. Deviations between bulk and SAM molecular transition dipole moments have been observed in other molecules containing phenyl units in their backbones [Arnold, R.; Terfort, A.; Woll, C. Langmuir 2001, 17, 4980-4989].
  • 103
    • 0141982661 scopus 로고    scopus 로고
    • note
    • While images of the 2-SAM have not been reported the 1-SAM has been imaged using STM with conflicting results. Dhirani and coworkers (ref 48) reported lattice constants of a = 5.2 ± 0.4 Å and b = 9.7 ± 0.9 Å with γ = 55° and proposed a (2√3 × √3),R30 structure in which the strong Au-S interaction is considered the driving force for formation of the commensurate structure. They proposed a rectangular unit cell with a = 4.99 Å, b = 8.64 Å, and γ = 90° in which there are two types of molecules configurations with differing heights on the long axis of the unit cell. A later ultrahigh vacuum (UHV) STM study by Yang and co-workers (ref 28), in contrast, reported a rectangular unit cell, incommensurate with the gold lattice, containing two molecules and exhibiting lattice parameters a = 5.0 ± 0.2 Å and b = 9.9 ± 0.4 Å. Both groups concluded that the molecules were arranged in a herringbone fashion on the Au surface and their images both reveal a ridgelike structure with different rows of 1 having different apparent heights. Our AFM images do not show these types of detailed features, as would be expected on the basis that AFM involves only force measurements in which the tips do not trace individual atomic features, as in STM, but rather involve multiple atom contacts. Studies are in progress in our laboratory to use UHV STM measurements to determine the detailed structures of the 2-SAM.
  • 104
    • 0141948087 scopus 로고    scopus 로고
    • note
    • + salt residues to the N1s peak.
  • 105
    • 0141878957 scopus 로고    scopus 로고
    • note
    • 2 antisymmetric stretch in the nitro-substituted monolayer. The substantially weaker dipole transitions in the spectra of a pure amine-substituted monolayer may be one reason for the lack of information in the vibrational spectra.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.