Electron Transmission through Self-Assembled Monolayers

and, Deborah Evans; Wampler, Rodric

doi:10.1021/jp984811p

Cited by 9 publications

(5 citation statements)

References 52 publications

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“…However, we believe a more likely explanation is that as electrons in the diamond impinge on the diamond-molecule interfaces, they are more effectively scattered than at the diamond-H interface because of the disordered nature of the molecular layers at the diamond-molecule interface. Previous experimental and theoretical studies of self-assembled monolayers on gold have shown reduced electron-transmission rates through disordered layers compared with ordered layers, which has been ascribed in part to enhanced scattering of the electrons passing through the disordered molecular layer. − We believe these electron scattering effects are the primary reason why the grafted layers of dodecene have lower secondary electron yield than the starting H-terminated diamond surface.…”

Section: Discussionmentioning

confidence: 93%

Direct Photopatterning and SEM Imaging of Molecular Monolayers on Diamond Surfaces: Mechanistic Insights into UV-Initiated Molecular Grafting

et al. 2007

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We have used X-ray photoelectron spectroscopy (XPS), infrared reflection-absorption spectroscopy, and field-emission scanning electron microscopy (SEM) to investigate the formation of single- and two-component molecular patterns by direct photochemical grafting of alkenes onto hydrogen-terminated diamond surfaces using sub-band gap 254 nm ultraviolet light. Trifluoroacetamide-protected 1-aminodec-1-ene (TFAAD) and 1-dodecene were used as model systems for grafting. Illumination with sub-band gap light can induce several different kinds of excitations, including creation of mobile electrons and holes in the bulk and creation of radicals at the surface and in the adjacent fluid, which induce grafting of the alkenes to the surface. SEM images of patterned molecular layers on nanocrystalline diamond surfaces reveal sharp transitions between functionalized and nonfunctionalized regions consistent with diffraction-limited excitation. However, identical experiments on type IIb single-crystal diamond yield a significantly more extended transition region in the molecular pattern. These data imply that the spatial resolution of the direct molecular photopatterning is affected by diffusion of charge carriers in the bulk of the diamond samples. The molecular contrast between surfaces with different terminations is consistent with the expected trends in molecular electron affinity. These results provide new mechanistic insights into the direct patterning and imaging of molecular monolayers on surfaces.

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Section: Discussionmentioning

confidence: 93%

Direct Photopatterning and SEM Imaging of Molecular Monolayers on Diamond Surfaces: Mechanistic Insights into UV-Initiated Molecular Grafting

et al. 2007

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“…Recently, we have been exploring the nature of the interface between water and self-assembled long-chain organic molecules. The interest in these systems is due partially to applications in science and technology. , For example, one application is in the field of reverse-phase liquid chromatography for the separation of structural isomers . The selectivity of the hydrocarbon phase is dependent on its order, which is measured by the conformation of the hydrocarbon chains (trans versus gauche) and the surface roughness.…”

Section: Introductionmentioning

confidence: 99%

Solvation Dynamics at the Interface between Water and Self-assembled Monolayers

Vieceli

Benjamin

2003

J. Phys. Chem. B

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Molecular dynamics computer simulations are used to study the solvation dynamics following an electronic transition in a chromophore adsorbed at the interface between water and chlorine-terminated self-assembled monolayers. By varying the composition of the monolayer and the degree of chlorination, the role of interface polarity and structure on the relaxation time can be elucidated. The relaxation times are found to be faster at smooth interfaces and at interfaces in which the degree of chlorination is larger. Both the water and the self-assembled molecules contribute to the dynamics. However, we find that most of the water contribution to the relaxation is due to water molecules in the first solvent shell while the monolayer contribution is mostly from chlorine-terminated hydrocarbon molecules in the outer solvation shell of the chromophore. The water relaxation is faster than the monolayer relaxation in each system, but it is always slower than that of bulk water. The validity of linear response theory is discussed, and comparisons are made between the relaxation in the systems studied here, simulations of liquid/liquid interfaces, and experimental solvation dynamics data.

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“…The interface between these systems and water can be investigated by a STM 10 (scanning tunneling microscope), an AFM 10 (atomic force microscope), neutron reflection, 12 electrochemical techniques, and other thermodynamic and surface characterization methods, such as wetting experiments 13 and nonlinear spectroscopic techniques. 14 Self-assembled monolayers with different electronic and molecular structures have been used in recent years to study a number of different molecular processes, such as electron transmission, 15 energy transfer, and spectroscopy. 16 In this paper, we consider the interface between water and five different self-assembled hydrocarbon monolayers.…”

Section: Introductionmentioning

confidence: 99%

Adsorption at the Interface between Water and Self-Assembled Monolayers: Structure and Electronic Spectra

and

Benjamin

2002

J. Phys. Chem. B

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The structure of the interface between water and self-assembled organic monolayers having different roughness and polarity is investigated by molecular dynamics computer simulations. The electronic absorption spectrum of an adsorbed chromophore at these different interfaces is computed and correlated with the structure of the interface. Several different electronic transitions characterized by different changes in the electric dipole moment are considered. We find that the effective polarity of the interface is greater than that of bulk water in contrast to the situation at several liquid/liquid interfaces, but in agreement with recent experiments at the liquid/solid interface. We show that this higher effective polarity is due to a contribution from the polar groups at the surface that is larger than the loss due to the decreased interaction with water.

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Electron Transmission through Self-Assembled Monolayers

Cited by 9 publications

References 52 publications

Direct Photopatterning and SEM Imaging of Molecular Monolayers on Diamond Surfaces: Mechanistic Insights into UV-Initiated Molecular Grafting

Direct Photopatterning and SEM Imaging of Molecular Monolayers on Diamond Surfaces: Mechanistic Insights into UV-Initiated Molecular Grafting

Solvation Dynamics at the Interface between Water and Self-assembled Monolayers

Adsorption at the Interface between Water and Self-Assembled Monolayers: Structure and Electronic Spectra

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