Surface Structure of A Liquid Perfluoropolyether Examined by Reactive Ion/Surface Scattering

1995 ◽  
Vol 380 ◽  
Author(s):  
T. Pradeep ◽  
S. A. Miller ◽  
H. W. Rohrs ◽  
B. Feng ◽  
R. G. Cooks
Keyword(s):  
Surface Structure ◽  
Metal Ion ◽  
Liquid Surface ◽  
Surface Scattering ◽  
Reactive Scattering ◽  
Self Assembled Monolayer ◽  
Molecular Systems ◽  
Surface Induced Dissociation ◽  
Chemical Sputtering ◽  
Surface Collision

ABSTRACTThis study shows that reactive ion/surface collisions can provide information on the surface structure of molecular systems. The microscopic structures of perfluorinated polyether (PFPE) liquid surfaces are characterized by ion/surface collision experiments in a mass spectrometer and the results are compared to those obtained with a fluorinated self-assembled monolayer (F-SAM) surface. Low energy (< 100 eV) beams of W+ and W(CO)6+ ions are used for surface-induced dissociation (SID) and ion/surface reactive scattering, while Xe+ and Kr+ beams are used for chemical sputtering experiments. Both the PFPE and F-SAM surfaces show similar SID fragments while reactions with W+ and W(CO)6+ lead to the scattered metal ion with multiple fluorine atoms attached. The main peaks in chemical sputtering spectra are similar for both surfaces as well. Both hydrogen probe beams and chemical sputtering confirm that the liquid PFPE surface is nearly free of impurities. Our results on both surfaces also suggest that the CF3 group of the monomer units is most likely projected outward from the bulk of the liquid surface.

The evaluation of the hyperfine interaction tensor components in molecular systems

1977 ◽  
Vol 354 (1677) ◽  
pp. 223-244 ◽  
Keyword(s):  
Angular Momentum ◽  
Hyperfine Interaction ◽  
Metal Ion ◽  
Molecular System ◽  
Slater Type Orbital ◽  
Molecular Systems ◽  
Principal Axes ◽  
Interaction Tensor ◽  
Electronic Wavefunction ◽  
General Method

In this paper a general method is developed to evaluate the nine hyperfine interaction tensor components, A αβ , arising from the electron orbital angular momentum and the electron spin dipolar-nuclear spin angular momentum interactions of an electron associated dominantly with one nucleus coupling with a nucleus with a non-zero magnetic moment, where the electronic wavefunction is described by a Slater-type orbital. The method handles long range and short range coupling including the free atom case. From the results the degree of non-coincidence of the principal axes of the g and A tensors and the n.m.r. shifts are evaluated. As an illustration the molecular system examined is a molecule containing a d 1 transition metal ion in a strong crystal field.

scholarly journals Stochastic Adsorption of Diluted Solute Molecules at Interfaces

2020 ◽  
Author(s):  
Jixin Chen
Keyword(s):  
Analytical Solution ◽  
Observation Time ◽  
Patterned Surfaces ◽  
Fractal Function ◽  
Self Assembled Monolayer ◽  
Power Law Decay ◽  
Sensing Platforms ◽  
Surface Collision ◽  
Measuring Frequency ◽  
Multiple Collisions

<div> <p>Here an analytical solution of Fick’s 2<sup>nd</sup> law is used to predict the diffusion and the stochastic adsorption of single diluted solute molecules on flat and patterned surfaces. The equations are then compared to the results of several numerical Monte Carlo simulations using a random walk model. The 1D diffusion simulations clarify that the dependence of the solute-surface collision rate on the observation-time (measurement time resolution) is because of the multiple collisions of the same molecules over different time regions. It also surprisingly suggests that due to the self-mimetic fractal function of diffusion, the equation should be corrected by a factor of two. The absorption rate of solute on an adsorptive surface is found to follow a power-law decay function due to an evolving concentration gradient near the surface along with the depletion of the bulk solute molecules on the surface, for example, in a self-assembled monolayer adsorption kinetics. Thus, the analytical equations developed to calculate the collision at a fixed measuring frequency can be extended to map the whole curve over time. In the last section of this work, 3D diffusion simulations suggest that the analytical solution is valid to predict the adsorption rate of the bulk solute to a small group of adsorptive target molecules/area on a bouncing surface, which is a critical process in analyzing the kinetics of many bio-sensing platforms.</p> </div>

Synthesis and Surface Structure of Thymine-Functionalized, Self-Assembled Monolayer-Protected Gold Nanoparticles

Langmuir ◽  
2007 ◽  
Vol 23 (18) ◽  
pp. 9170-9177 ◽  
Author(s):  
Jingfang Zhou ◽  
David A. Beattie ◽  
Rossen Sedev ◽  
John Ralston
Keyword(s):  
Gold Nanoparticles ◽  
Surface Structure ◽  
Self Assembled Monolayer ◽  
Self Assembled

scholarly journals Fast Fragmentation During Surface-Induced Dissociation: An Examination of Peptide Size and Structure

2020 ◽  
Author(s):  
George Barnes ◽  
Amanda Shlaferman ◽  
Monica Strain
Keyword(s):  
Self Assembled Monolayer ◽  
Collision Event ◽  
Direct Dynamics ◽  
Surface Induced Dissociation ◽  
Self Assembled ◽  
Dynamics Simulations ◽  
Size And Structure

We present the results of direct dynamics simulations of surface-induced dissociation for protonated versions of A$_\mathrm{n}$K, KA$_\mathrm{n}$ (n = 1, 3, and 5), AcA$_\mathrm{7}$K, and AcKA$_\mathrm{7}$ for collisions with a fluorinated self-assembled monolayer surface. We focus on elucidating fast fragmentation events, which takes place in coincidence with the collision event. Such events generate a large number of products, and hence, are not easily understood through chemical intuition. Our simulations show distinct differences between the A$_{\mathrm{n}}$K/AcA$_\mathrm{7}$K and KA$_{\mathrm{n}}$/AcKA$_7$ series of peptides, with the former being more reactive, and the latter more selective. Backbone rearrangements and sidechain fragmentation are also seen.<br>

Mass Spectrometry for Synthesis and Analysis

2018 ◽  
Vol 11 (1) ◽  
pp. 1-28 ◽  
Author(s):  
R. Graham Cooks ◽  
Xin Yan
Keyword(s):  
Mass Spectrometry ◽  
Essential Element ◽  
Tissue Imaging ◽  
Small Scale ◽  
Soft Landing ◽  
Surface Induced Dissociation ◽  
Surface Collision ◽  
Collision Processes ◽  
Ion Soft Landing ◽  
Exciting Area

Mass spectrometry is the science and technology of ions. As such, it is concerned with generating ions, measuring their properties, following their reactions, isolating them, and using them to build and transform materials. Instrumentation is an essential element of these activities, and analytical applications are one driving force. Work from the Aston Laboratories at Purdue University's Department of Chemistry is described here, with an emphasis on accelerated reactions of ions in solution and small-scale synthesis; ion/surface collision processes, including surface-induced dissociation (SID) and ion soft landing; and applications to tissue imaging. Our special interest in chirality and the chemistry behind the origins of life is also featured together with the exciting area of tissue diagnostics.

scholarly journals Monte Carlo Simulation of Stochastic Adsorption of Diluted Solute Molecules at an Interface

2020 ◽  
Author(s):  
Jixin Chen
Keyword(s):  
Monte Carlo ◽  
Analytical Solution ◽  
Observation Time ◽  
Patterned Surfaces ◽  
Fractal Function ◽  
Self Assembled Monolayer ◽  
Power Law Decay ◽  
Sensing Platforms ◽  
Surface Collision ◽  
Measuring Frequency

<div> <p>Here an analytical solution of Fick’s 2<sup>nd</sup> law is used to predict the diffusion and the stochastic adsorption of single diluted solute molecules on flat and patterned surfaces. The equations are then compared to the results of several numerical Monte Carlo simulations using a random walk model. The 1D diffusion simulations clarify that the dependence of the solute-surface collision rate on the observation-time (measurement time resolution) is because of the multiple collisions of the same molecules over different time regions. It also surprisingly suggests that due to the self-mimetic fractal function of diffusion, the equation should be corrected by a factor of two. The absorption rate of solute on an adsorptive surface is found to follow a power-law decay function due to an evolving concentration gradient near the surface along with the depletion of the bulk solute molecules on the surface, for example, in a self-assembled monolayer adsorption kinetics. Thus, the analytical equations developed to calculate the collision at a fixed measuring frequency can be extended to map the whole curve over time. In the last section of this work, 3D diffusion simulations suggest that the analytical solution is valid to predict the adsorption rate of the bulk solute to a small group of adsorptive target molecules/area on a bouncing surface, which is a critical process in analyzing the kinetics of many bio-sensing platforms.</p> </div>

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