scholarly journals X-ray Emission Spectra of Some Carbon-containing Molecules

1986 ◽  
Vol 39 (5) ◽  
pp. 717 ◽  
Author(s):  
RA Phillips ◽  
FP Larkins
Keyword(s):  
Transition Probabilities ◽  
Emission Spectra ◽  
Fluorescence Yield ◽  
Total Carbon ◽  
Molecular Orbital Calculations ◽  
Electronic Relaxation ◽  
X Ray ◽  
Hartree Fock ◽  
Relaxation Effects ◽  
Absolute Transition

Ab initio molecular orbital calculations for the energy and intensity of X-ray transitions associated with the carbon monoxide, hydrogen cyanide and carbon dioxide molecules have been calculated at the Hartree-Fock level. It is demonstrated that in general the absolute transition probabilities are sensitive to the inclusion of electronic relaxation effects and interatomic transition moment contributions. It is concluded that calculations for molecular X-r!ly emission henomena should be undertaken at least at the multicentre relaxed Hartree-Fock level to achieve a realistic basis for comparison with experiment. Total carbon-K X-ray rates do not show a strong variation with changes in the molecular environment. The total rates are of a similar magnitude to those reported for the atom. The calculated carbon-K fluorescence yield is also similar in both the carbon atom and the CO2 molecule.

scholarly journals Atomic X-ray Transition Probabilities: A Comparison of the Dipole Length, Velocity and Acceleration Forms

1984 ◽  
Vol 37 (1) ◽  
pp. 45 ◽  
Author(s):  
HM Quiney ◽  
FP Larkins
Keyword(s):  
Transition Probabilities ◽  
Nuclear Charge ◽  
Principal Quantum Number ◽  
Dipole Transition ◽  
Final States ◽  
X Ray ◽  
Hartree Fock ◽  
Isoelectronic Series ◽  
Rydberg Electron ◽  
Dipole Length

The length, velocity and acceleration forms of the dipole transition operator are examined in calculations of diagram and satellite X-ray emission probabilities in the Ne + to Ar 9 + isoelectronic series. All calculations are within the relaxed nonrelativistic Hartree-Fock framework, using separately optimized numerical wavefunctions for the initial and final electronic states. Divergence between the alternative forms of the transition moment, as the principal quantum 'number of the Rydberg electron and nuclear charge are increased, is discussed in the context of electron correlation differences between the initial and final states.

X-RAY SPECTROSCOPIC ANALYSIS OF BORON-NITRIDE CLUSTERS DEPOSITED BY ION-PLATING METHOD

1996 ◽  
Vol 03 (01) ◽  
pp. 1051-1057 ◽  
Author(s):  
H. KOHZUKI ◽  
M. MOTOYAMA ◽  
T. KANEYOSHI ◽  
Y. KOWADA ◽  
J. KAWAI ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Emission Spectrum ◽  
Cubic Boron Nitride ◽  
Emission Spectra ◽  
Satellite Peak ◽  
X Ray ◽  
Ion Plating ◽  
Hartree Fock ◽  
Plating Method ◽  
Diffraction Patterns

Cubic boron-nitride (c-BN) films were deposited on a silicon substrate by varying the deposition time, using a reactive ion-plating method. In order to investigate the growth mechanism of c-BN films, these c-BN films were characterized by x-ray emission spectra of boron (B K x-ray emission spectra), infrared absorption spectra, selected area diffraction patterns, and TEM microstructures. It was found that the BN film with sp2 bonding formed initially on the substrate and subsequently c-BN film formed. The c-BN film was composed of fine crystallites with a size of about 10 nm and with random orientation. In the case of the B K x-ray emission spectrum from the BN film with sp 2 bonding, the intensity of the satellite peak at the short-wavelength side was extremely stronger than that of sp 2-bonded BN-like turbostratic or hexagonal BN. As a result of calculation of the B K x-ray emission spectrum of BN using the discrete variational Hartree-Fock-Slater (DV-Xα) method, it was found that the satellite peak intensity increased with formation of the fine BN cluster having two-coordinated boron (which has a dangling bond) and with decreasing size of the cluster. Therefore, it is considered that the BN film with sp 2 bonding was composed of the very fine BN cluster having two-coordinated borons, and became the precursor of c-BN film at the interface between the substrate and c-BN film.

Variable-Temperature Ultraviolet Photoelectron-Spectroscopy of the Keto-Enol Tautomers of Pentane-2,4-Dione

1987 ◽  
Vol 40 (3) ◽  
pp. 599 ◽  
Author(s):  
NS Hush ◽  
MK Livett ◽  
JB Peel ◽  
GD Willett
Keyword(s):  
Photoelectron Spectroscopy ◽  
Energy Region ◽  
Variable Temperature ◽  
Photoelectron Spectra ◽  
Ultraviolet Photoelectron Spectroscopy ◽  
Molecular Orbital Calculations ◽  
Electronic Relaxation ◽  
Relaxation Effects ◽  
Enol Tautomer ◽  
Scf Calculations

The HeI photoelectron spectra of pentane-2,4-dione measured at various temperatures have been subjected to a spectrum-stripping technique to enable isolation of the complete HeI photoelectron spectra of the keto and enol tautomers. The resulting spectrum-stripping coefficients allow evaluation of the enolization equilibrium constant at each temperature and subsequently the enthalpy of enolization. Interpretation of the photoelectron spectra is achieved with the use of ab initio molecular orbital calculations. Photoionization of non-bonding oxygen, and π -type electrons, contribute to the low ionization energy region of the spectrum, with a πCC < no- <πCO ordering for the enol tautpmer , and no- < no+ < πCO+ for the keto tautomer . Because of different electronic relaxation effects, ∆SCF calculations are required to predict correctly the observed πCC/no- spacing for the enol tautomer.

Electronic relaxation effects on x-ray spectra of titanium and transition-metal carbides and nitrides

1982 ◽  
Vol 25 (10) ◽  
pp. 6349-6366 ◽  
Author(s):  
A. Balzarotti ◽  
M. De Crescenzi ◽  
L. Incoccia
Keyword(s):  
Transition Metal ◽  
Electronic Relaxation ◽  
Metal Carbides ◽  
X Ray ◽  
Transition Metal Carbides ◽  
Relaxation Effects

Chemical State Analysis by Soft X-ray Emission Spectra with Molecular-Orbital Calculations

1990 ◽  
Vol 34 ◽  
pp. 91-103
Author(s):  
Jun Kawai
Keyword(s):  
Molecular Orbital ◽  
Emission Spectra ◽  
Molecular Orbital Calculation ◽  
Chemical State ◽  
Molecular Orbital Calculations ◽  
Metal Compounds ◽  
X Ray ◽  
Chemical Effects ◽  
Avoided Crossing ◽  
Simple Picture

This paper deals with soft X-ray spectra of compounds which have one or more spectator hole(s) in the valence orbitals. The aim is to give a simple picture of the complicated chemical effects and to describe implications of the chemical effects to know the chemical state from the complicated spectra of materials. The first example of the system which has a spectator hole in the valence orbital is the intensity modifications of the shake-off satellites (KM-→LM) in chlorine Kα spectra. The second example of the system which has spectator holes in the valence orbitals is the multiplet structure of Lα spectra of the transition-metal compounds. It is described that the chemical effects of these two systems are clearly interpreted by the avoided crossing [1] of the molecular orbitals, one of which has a localized hole. We also describe the systems which have no spectator holes. The interpretation of the X-ray spectra of these systems are easy by a molecular-orbital calculation at the ground state.

Adaptation of the Gelius intensity model in semiempirical HAM/3 molecular orbital calculations of valence photoelectron spectra excited by X-ray radiation

1985 ◽  
Vol 63 (7) ◽  
pp. 2007-2011 ◽  
Author(s):  
Delano P. Chong
Keyword(s):  
Ab Initio ◽  
Molecular Orbital ◽  
Cross Sections ◽  
Present Method ◽  
Photoelectron Spectra ◽  
Molecular Orbital Calculations ◽  
Ionization Energies ◽  
X Ray ◽  
Hartree Fock ◽  
Intensity Model

The Gelius intensity model has been adapted in the semiempirical HAM/3 method to calculate the valence ionization energies and intensities in XPS. Both semiempirical and àb initio Hartree–Fock–Slater atomic photoionization cross-sections can be used. Results presented for C2H2, C2H4, N2, H2O, CH3OH, and CH2F2 demonstrate that the present method can facilitate the interpretation of experimental XPS.

scholarly journals Experimental and theoretical lifetimes and transition probabilities for spectral lines in Nb II

2019 ◽  
Vol 627 ◽  
pp. A102
Author(s):  
H. Nilsson ◽  
L. Engström ◽  
H. Lundberg ◽  
H. Hartman ◽  
P. Palmeri ◽  
...  
Keyword(s):  
Transition Probabilities ◽  
Branching Fractions ◽  
Spectral Lines ◽  
Fourier Transform Spectrometer ◽  
Core Polarization ◽  
Time Resolved ◽  
Excitation Scheme ◽  
Hartree Fock ◽  
Two Photon ◽  
Absolute Transition

Aims. We have measured and calculated lifetimes of high lying levels in Nb II, and derived absolute transition probabilities by combining the lifetimes with experimental branching fractions.Methods. The lifetimes were measured using time-resolved laser-induced fluorescence in a two-photon and two-step excitation scheme. The branching fractions were measured in intensity calibrated spectra from a hollow cathode discharge, recorded with a Fourier transform spectrometer. The calculations were performed with the relativistic Hartree–Fock method including core polarization.Results. We report experimental lifetimes of 13 levels in the 4d3(4F)5d and 4d3(4F)6s subconfigurations, at an energy around 70 000 cm−1. By combining the lifetimes with experimental branching fractions absolute transition probabilities of 59 lines are derived. The experimental results are compared with calculated values.

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