scholarly journals A VIBRATIONAL MODEL FOR ACCURATE DETERMINATION OF OSCILLATOR STRENGTHS IN HYDROGEN BONDED COMPLEXES

2014 ◽  
Author(s):  
Kasper Mackeprang ◽  
Henrik Kjærgaard
Keyword(s):  
Accurate Determination ◽  
Oscillator Strengths ◽  
Bonded Complexes ◽  
Hydrogen Bonded

scholarly journals Accurate thermodynamic properties of gas phase hydrogen bonded complexes

2016 ◽  
Vol 18 (34) ◽  
pp. 23831-23839 ◽  
Author(s):  
Anne S. Hansen ◽  
Zeina Maroun ◽  
Kasper Mackeprang ◽  
Benjamin N. Frandsen ◽  
Henrik G. Kjaergaard
Keyword(s):  
Complex Formation ◽  
Thermodynamic Properties ◽  
Equilibrium Constant ◽  
Gas Phase ◽  
Accurate Determination ◽  
Enthalpy Of Complex Formation ◽  
Bonded Complexes ◽  
Hydrogen Bonded

The increase in temperature causes a decrease in equilibrium constant, which makes accurate determination of the enthalpy of complex formation possible.

Determination of Binding Constants of Hydrogen-Bonded Complexes by ITC, NMR CIS, and NMR Diffusion Experiments

2011 ◽  
Vol 2011 (11) ◽  
pp. 2066-2074 ◽  
Author(s):  
Christiane Dethlefs ◽  
Jens Eckelmann ◽  
Hauke Kobarg ◽  
Thomas Weyrich ◽  
Stefan Brammer ◽  
...  
Keyword(s):  
Binding Constants ◽  
Nmr Diffusion ◽  
Bonded Complexes ◽  
Hydrogen Bonded

Calorimetric Determination of the Equilibrium Constant and the Heat of Formation of Hydrogen Bonded Complexes

Nature ◽  
1968 ◽  
Vol 218 (5140) ◽  
pp. 461-462 ◽  
Author(s):  
D. NEERINCK ◽  
A. VAN AUDENHAEGE ◽  
L. LAMBERTS ◽  
P. HUYSKENS
Keyword(s):  
Equilibrium Constant ◽  
Heat Of Formation ◽  
Calorimetric Determination ◽  
Bonded Complexes ◽  
Hydrogen Bonded

Bonding topology, hydrogen bond strength, and vibrational chemical shifts on hetero-ring hydrogen-bonded complexes — Theoretical insights revisited

2012 ◽  
Vol 90 (4) ◽  
pp. 368-375 ◽  
Author(s):  
Boaz G. Oliveira ◽  
Regiane C. M. U. Araújo
Keyword(s):  
Hydrogen Bond ◽  
Bond Strength ◽  
Chemical Shifts ◽  
Dipole Moments ◽  
Interaction Strength ◽  
Hydrogen Bond Strength ◽  
Electronic Densities ◽  
Bonded Complexes ◽  
Hydrogen Bonded

This work presents a theoretical study about the interaction strength of the hydrogen-bonded complexes C2H4O···HF, C3H6O···HF, C2H4O···HCF3, and C3H6O···HCF3 at the B3LYP/6–311++G(d,p) level. The structures, hydrogen bond energies, charge transfers, and dipole moments of these complexes were analyzed in accordance with routine spectroscopy events, such as the red- and blue-shifts on the stretch frequencies of the proton donors (HF and HCF3). The ChelpG atomic charges were used to quantify the charge-transfer fluxes from electron donor (O) towards to acceptors (HF or HCF3). Moreover, the topological calculations on the basis of the quantum theory of atoms in molecules (QTAIM) approach were also used to unveil the hydrogen bond strength (O···H), mainly in the determination of their electronic densities and Laplacian shapes.

A quantitative approach to inner shell losses

1978 ◽  
Vol 36 (1) ◽  
pp. 526-527 ◽  
Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Background Intensity ◽  
Core Excitation ◽  
Quantitative Basis ◽  
Cross Section Differential ◽  
Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

Fast calibration of CBED patterns for quantitative analysis

1993 ◽  
Vol 51 ◽  
pp. 674-675
Author(s):  
M.A. Gribelyuk ◽  
M. Rühle
Keyword(s):  
Reciprocal Lattice ◽  
Accurate Determination ◽  
Incident Beam ◽  
Crystal Thickness ◽  
Structure Model ◽  
Beam Direction ◽  
Transmitted Beam ◽  
Reciprocal Vector ◽  
On Line

A new method is suggested for the accurate determination of the incident beam direction K, crystal thickness t and the coordinates of the basic reciprocal lattice vectors V1 and V2 (Fig. 1) of the ZOLZ plans in pixels of the digitized 2-D CBED pattern. For a given structure model and some estimated values Vest and Kest of some point O in the CBED pattern a set of line scans AkBk is chosen so that all the scans are located within CBED disks.The points on line scans AkBk are conjugate to those on A0B0 since they are shifted by the reciprocal vector gk with respect to each other. As many conjugate scans are considered as CBED disks fall into the energy filtered region of the experimental pattern. Electron intensities of the transmitted beam I0 and diffracted beams Igk for all points on conjugate scans are found as a function of crystal thickness t on the basis of the full dynamical calculation.

Computer-Assisted High-Re Solution TEM

1990 ◽  
Vol 48 (1) ◽  
pp. 162-163
Author(s):  
F.A. Ponce ◽  
H. Hikashi
Keyword(s):  
Signal To Noise Ratio ◽  
Accurate Determination ◽  
Computer Software ◽  
Video Camera ◽  
Image Contrast ◽  
Objective Lens ◽  
Computer Assisted ◽  
Optical Parameters ◽  
Astigmatism Correction

The determination of the atomic positions from HRTEM micrographs is only possible if the optical parameters are known to a certain accuracy, and reliable through-focus series are available to match the experimental images with calculated images of possible atomic models. The main limitation in interpreting images at the atomic level is the knowledge of the optical parameters such as beam alignment, astigmatism correction and defocus value. Under ordinary conditions, the uncertainty in these values is sufficiently large to prevent the accurate determination of the atomic positions. Therefore, in order to achieve the resolution power of the microscope (under 0.2nm) it is necessary to take extraordinary measures. The use of on line computers has been proposed [e.g.: 2-5] and used with certain amount of success.We have built a system that can perform operations in the range of one frame stored and analyzed per second. A schematic diagram of the system is shown in figure 1. A JEOL 4000EX microscope equipped with an external computer interface is directly linked to a SUN-3 computer. All electrical parameters in the microscope can be changed via this interface by the use of a set of commands. The image is received from a video camera. A commercial image processor improves the signal-to-noise ratio by recursively averaging with a time constant, usually set at 0.25 sec. The computer software is based on a multi-window system and is entirely mouse-driven. All operations can be performed by clicking the mouse on the appropiate windows and buttons. This capability leads to extreme friendliness, ease of operation, and high operator speeds. Image analysis can be done in various ways. Here, we have measured the image contrast and used it to optimize certain parameters. The system is designed to have instant access to: (a) x- and y- alignment coils, (b) x- and y- astigmatism correction coils, and (c) objective lens current. The algorithm is shown in figure 2. Figure 3 shows an example taken from a thin CdTe crystal. The image contrast is displayed for changing objective lens current (defocus value). The display is calibrated in angstroms. Images are stored on the disk and are accessible by clicking the data points in the graph. Some of the frame-store images are displayed in Fig. 4.

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