AC/DC Analysis: Broad and Comprehensive Approach to Analyze Infrared Intensities at the Atomic Level

Broad and Comprehensive Approach to Evaluate Infrared Intensities at Atomic Level: The AC/DC Analysis

10.26434/chemrxiv.12909593 ◽

2020 ◽

Author(s):

Wagner Richter ◽

Leonardo Duarte ◽

Luciano N. Vidal ◽

Roy E. Bruns

Keyword(s):

Electronic Structure ◽

Population Analysis ◽

Atomic Level ◽

Numerical Results ◽

Comprehensive Approach ◽

The Other ◽

Single Atom ◽

Infrared Intensity ◽

Infrared Intensities ◽

Automated Protocol

<div>We present a complete theoretical protocol to split infrared intensity in terms owing to individual atoms in two different but related approaches: the Atomic Contributions (AC's) how how the entire molecule motion is noticed by the electronic structure of a single atom, and therefore reflected on the intensity. On the other hand, the Dynamic Contributions (DC's) show how the displacement of a single atom is noticed by the electronic structure of the entire molecule, and reflected on the IR intensity. The two analyses are complementary ways of partitioning the same total intensity, and conserve most of the features of the total intensity itself. Combined they are called the AC/DC analysis. These can be further partitioned following the CCTDP (or CCT) models regarding the population analysis chosen by the researcher. The main conceptual features of the equations are highlighted and representative numerical results are shown to support the interpretation of the equations. The results are invariant to rotation and translation and can readily be extended to molecules of any size, shape or symmetry. A fully automated protocol managed by Placzek program is made available, free of charge.</div>

Download Full-text

Broad and Comprehensive Approach to Evaluate Infrared Intensities at Atomic Level: The AC/DC Analysis

10.26434/chemrxiv.12909593.v1 ◽

2020 ◽

Author(s):

Wagner Richter ◽

Leonardo Duarte ◽

Luciano N. Vidal ◽

Roy E. Bruns

Keyword(s):

Electronic Structure ◽

Population Analysis ◽

Atomic Level ◽

Numerical Results ◽

Comprehensive Approach ◽

The Other ◽

Single Atom ◽

Infrared Intensity ◽

Infrared Intensities ◽

Automated Protocol

<div>We present a complete theoretical protocol to split infrared intensity in terms owing to individual atoms in two different but related approaches: the Atomic Contributions (AC's) how how the entire molecule motion is noticed by the electronic structure of a single atom, and therefore reflected on the intensity. On the other hand, the Dynamic Contributions (DC's) show how the displacement of a single atom is noticed by the electronic structure of the entire molecule, and reflected on the IR intensity. The two analyses are complementary ways of partitioning the same total intensity, and conserve most of the features of the total intensity itself. Combined they are called the AC/DC analysis. These can be further partitioned following the CCTDP (or CCT) models regarding the population analysis chosen by the researcher. The main conceptual features of the equations are highlighted and representative numerical results are shown to support the interpretation of the equations. The results are invariant to rotation and translation and can readily be extended to molecules of any size, shape or symmetry. A fully automated protocol managed by Placzek program is made available, free of charge.</div>

Download Full-text

Atomic-level imaging of the surface structure of Ag2O

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100113160 ◽

1984 ◽

Vol 42 ◽

pp. 656-657

Author(s):

William Krakow

Keyword(s):

High Vacuum ◽

Atomic Level ◽

Ultra High Vacuum ◽

Research Groups ◽

Resolution Electron ◽

Surface Reconstructions ◽

Order Of Magnitude ◽

High Resolution Electron Microscope ◽

Saturated Structure ◽

Transmission And Reflection

In recent years electron microscopy has been used to image surfaces in both the transmission and reflection modes by many research groups. Some of this work has been performed under ultra high vacuum conditions (UHV) and apparent surface reconstructions observed. The level of resolution generally has been at least an order of magnitude worse than is necessary to visualize atoms directly and therefore the detailed atomic rearrangements of the surface are not known. The present author has achieved atomic level resolution under normal vacuum conditions of various Au surfaces. Unfortunately these samples were exposed to atmosphere and could not be cleaned in a standard high resolution electron microscope. The result obtained surfaces which were impurity stabilized and reveal the bulk lattice (1x1) type surface structures also encountered by other surface physics techniques under impure or overlayer contaminant conditions. It was therefore decided to study a system where exposure to air was unimportant by using a oxygen saturated structure, Ag2O, and seeking to find surface reconstructions, which will now be described.

Download Full-text

Surface roughness measurements of vanadium-contaminated fluidized cracking catalysts by atomic force microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100166798 ◽

1996 ◽

Vol 54 ◽

pp. 866-867

Author(s):

H. Kinney ◽

M.L. Occelli ◽

S.A.C. Gould

Keyword(s):

Surface Roughness ◽

Zeolite Y ◽

Atomic Level ◽

Microporous Structure ◽

Contact Mode ◽

Force Microscopy ◽

Atomic Force ◽

Before And After ◽

Roughness Measurements ◽

Cracking Catalysts

For this study we have used a contact mode atomic force microscope (AFM) to study to topography of fluidized cracking catalysts (FCC), before and after contamination with 5% vanadium. We selected the AFM because of its ability to well characterize the surface roughness of materials down to the atomic level. It is believed that the cracking in the FCCs occurs mainly on the catalysts top 10-15 μm suggesting that the surface corrugation could play a key role in the FCCs microactivity properties. To test this hypothesis, we chose vanadium as a contaminate because this metal is capable of irreversibly destroying the FCC crystallinity as well as it microporous structure. In addition, we wanted to examine the extent to which steaming affects the vanadium contaminated FCC. Using the AFM, we measured the surface roughness of FCCs, before and after contamination and after steaming.We obtained our FCC (GRZ-1) from Davison. The FCC is generated so that it contains and estimated 35% rare earth exchaged zeolite Y, 50% kaolin and 15% binder.

Download Full-text