Temperature Effects in the Vibrational Spectra of Self-Assembled Monolayers

Forster-Tonigold, Katrin; Stammer, Xia; Wöll, Christof; Groß, Axel

doi:10.1103/physrevlett.111.086102

Cited by 10 publications

(7 citation statements)

References 32 publications

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“…1. This adsorption configuration is similar to what was found by various theoretical studies of thiolate adsorbed on Au(111) [38][39][40]. In our MBD@rsSCS calculations, the PEG(thiol) molecules are tilted from the surface normal by 29.5 -31.9 • depending on the number of repeat units.…”

Section: Adsorption Geometrysupporting

confidence: 88%

Work-function modification of PEG(thiol) adsorbed on the Au(111) surface: A first-principles study

Kim

Guļāns

Draxl

2020

Phys. Rev. Materials

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The possibility of modifying the work function of electrodes is important for optimizing the energy barriers for charge-injection (extraction) at the interface to an organic material. In this study, we perform density-functional-theory calculations to investigate the impact of dithiol-terminated polyethylene glycol (PEG(thiol)) based self-assembled monolayers (SAMs) with different numbers of PEG repeat units on the work function of the Au(111) surface. We find that a monolayer of PEG(thiol) decreases the work function of the Au(111) surface, where the magnitude of this reduction strongly depends on the length of the PEG backbone. The main contribution arises from the dipole due to the adsorption-induced charge rearrangement at the interface. Our work reveals a pronounced odd-even effect, which can be traced back to the dipole moment of the PEG(thiol) layer.

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Section: Adsorption Geometrysupporting

confidence: 88%

Work-function modification of PEG(thiol) adsorbed on the Au(111) surface: A first-principles study

Kim

Guļāns

Draxl

2020

Phys. Rev. Materials

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“…Microscopic understanding of the thermodynamics and kinetics of organic molecules at inorganic substrates plays an increasingly important role in modern surface science and technology [1][2][3][4][5][6]. Obviously, the predictive modeling and understanding of the structure, stability, and dynamics of such hybrid systems is an essential prerequisite for tuning their electronic properties and functions [7][8][9][10].…”

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confidence: 99%

Steps or Terraces? Dynamics of Aromatic Hydrocarbons Adsorbed at Vicinal Metal Surfaces

2015

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The study of how molecules adsorb, diffuse, interact, and desorb from imperfect surfaces is essential for a complete understanding of elementary surface processes under relevant pressure and temperature conditions. Here we use first-principles calculations to study the adsorption of benzene and naphthalene on a vicinal Cu(443) surface with the aim to gain insight into the behavior of aromatic hydrocarbons on realistic surfaces at a finite temperature. Upon strong adsorption at step edges at a low temperature, the molecules then migrate from the step to the (111) terraces, where they can freely diffuse parallel to the step edge. This migration happens at temperatures well below the onset of desorption, suggesting a more complex dynamical picture than previously proposed from temperature-programed desorption studies. The increase of the adsorption strength observed in experiments for Cu(443) when compared to Cu (111) is explained by a stronger long-range van der Waals attraction between the hydrocarbons and the step edges of the Cu(443) surface. Our calculations highlight the need for time-resolved experimental studies to fully understand the dynamics of molecular layers on surfaces.

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“…37,38 IR intensity computed as the square of the changes in the dipole moment would change with tilt angles and their dynamic nature with temperature distribution has been observed by Forster-Tonigold et al for benzylmercaptan assembly on Au {111} through a combined vibrational spectroscopy and ab initio molecular dynamics (AIMD) approach. 37 The variance in the tilt angle distribution in the benzylmercaptan study was seen to increase with temperature and the effects of temperature change were seen as crucial for comparison of measured (IR) and calculated (AIMD) spectra. Sum Frequency Generation (SFG) spectroscopy also quantied changes in the tilt angle through changes in the conformation of the terminal group.…”

Section: Network Modulationmentioning

confidence: 86%

“…The variance in the S-O tilt angle distribution with temperature would be a result of the variance in end-group orientation and affect dipole moments 37 and spectra. 37,38 IR intensity computed as the square of the changes in the dipole moment would change with tilt angles and their dynamic nature with temperature distribution has been observed by Forster-Tonigold et al for benzylmercaptan assembly on Au {111} through a combined vibrational spectroscopy and ab initio molecular dynamics (AIMD) approach. 37 The variance in the tilt angle distribution in the benzylmercaptan study was seen to increase with temperature and the effects of temperature change were seen as crucial for comparison of measured (IR) and calculated (AIMD) spectra.…”

Section: Network Modulationmentioning

confidence: 99%

Epitaxial transfer through end-group coordination modulates the odd–even effect in an alkanethiol monolayer assembly

2014

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Short spacer length and high end-group coordination lead to the top network acting as a template for the buried sulfur-gold interface of n-alkanethiols (SH-(CH2)n-OH or SH-(CH2)n-CH3) on gold {111}. Annealing and templating both drive toward a higher sampling of the spatially favorable bridge adsorption sites. The hydrogen-bonded network increases in strength by increasing the number of hydrogens participating per oxygen, from 1.75 to 1.98 for n = 14-30. Higher n leads to better packing (five times for hydroxyl-terminated and seven times for methyl-terminated for n = 14-30) and stability of monolayers, while lower n results in better epitaxial transfer (transfer coefficient ratio = 13.5 for {SH-(CH2)14-OH}/{SH-(CH2)30-CH3}) and actuation. Odd values of n for the hydroxyl-terminated n-alkanethiols lead to lattice spacing of an average of 0.04 ± 0.01 Å higher than even values. There is a structural transition in properties around spacer length n = 24-27. Characterization of monolayer assembly through correlation between adatom and network layers provides recursive design principles for actuation and sensing applications.

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Temperature Effects in the Vibrational Spectra of Self-Assembled Monolayers

Cited by 10 publications

References 32 publications

Work-function modification of PEG(thiol) adsorbed on the Au(111) surface: A first-principles study

Work-function modification of PEG(thiol) adsorbed on the Au(111) surface: A first-principles study

Steps or Terraces? Dynamics of Aromatic Hydrocarbons Adsorbed at Vicinal Metal Surfaces

Epitaxial transfer through end-group coordination modulates the odd–even effect in an alkanethiol monolayer assembly

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