Accurate determination of low state rotational quantum numbers (J < 4) from planar-jet and liquid nitrogen cell absorption spectra of methane near 1.4 micron

Ondřej Votava; Milan Mašát; Petr Pracna; Samir Kassi; Alain Campargue

doi:10.1039/b922109c

Die Dissoziation des C2-Moleküls durch Rotation

Zeitschrift für Naturforschung A ◽

10.1515/zna-1967-1226 ◽

1967 ◽

Vol 22 (12) ◽

pp. 2023-2026b ◽

Cited By ~ 1

Author(s):

G. Messerle ◽

L. Krauss

Keyword(s):

Dissociation Energy ◽

Accurate Determination ◽

Low Pressure ◽

Rotational Structure ◽

Quantum Numbers ◽

Very High

The C2-spectrum was excited i low pressure arc with an electrically heated tungstencathode. In this arc the rotational structure of the C2 bands could be followed up to very high rotational quantum numbers. In the c1IIg state a dissociation by rotation was observed. This effect yields D0(C2) = (6,11 ± 0,04) eV. The dissociation by rotation allows the accurate determination of the dissociation energy. Additionally the dissociation products of the IIg states could be fixed unambigously.

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Bulk Solubility and Speciation of Plutonium(VI) in Phosphate-Containing Solutions

MRS Proceedings ◽

10.1557/proc-294-739 ◽

1992 ◽

Vol 294 ◽

Cited By ~ 3

Author(s):

H. T. Weger ◽

S. Okajima ◽

J. C. Cunnane ◽

D.T Reed

Keyword(s):

Absorption Spectra ◽

Accurate Determination ◽

Absorption Bands ◽

Initial Ph ◽

Colloid Formation

ABSTRACTThe solubility and speciation of Pu(VI) with phosphate is being investigated to determine the ability of phosphate to act as an actinide getter. In the initial studies performed, solubility was approached from oversaturation at an initial pH = 4, 10 and 13.4. Absorption spectra were recorded, the solution filtered, and the filtrate analyzed for Pu content. Absorption spectra were obtained at varying phosphate concentrations, and at pH of 2.7 to 11.9. The effect of complexation on the 833 nm Pu(VI) band was characterized. Evidence for three phosphate complexes was obtained for pH < 10, which have absorption bands at 842, 846 and 849 nm. Evidence for colloid formation was observed, but is not conclusive. The possible presence of colloids prevented an accurate determination of true solubility. A concentration of 10−5 to 10−6M Pu(VI) was measured in solutions at pH ≤ 10 that was filtered with a 50 nm filter. Pu(VI)-phosphate complexes predominated at pH ≤ 11.6. At higher pH, however, only hydrolyzed Pu(VI) was detected. At pH = 12, the concentration of Pu(VI) was as high as 10−4M.

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A quantitative approach to inner shell losses

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010010977x ◽

1978 ◽

Vol 36 (1) ◽

pp. 526-527 ◽

Cited By ~ 2

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

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Fast calibration of CBED patterns for quantitative analysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100149209 ◽

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.

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Computer-Assisted High-Re Solution TEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100179567 ◽

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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