IR-Absorption Spectra of Impurities in 6H-SiC

1994 ◽  
Vol 339 ◽  
Author(s):  
F. Engelbrecht ◽  
R. Helbig
Keyword(s):  
Temperature Dependence ◽  
Excited States ◽  
Oscillator Strengths ◽  
Electronic Transitions ◽  
Ir Absorption ◽  
Orbit Splitting ◽  
Ir Absorption Spectra ◽  
Nitrogen Donor ◽  
Splitting Energy ◽  
Vibronic Transitions

ABSTRACTWe performed infrared absorption and reflectivity measurements on serverai 6H-SiC samples at variable temperatures between T=5K and T=300K. From the temperature dependence of the observed absorption lines we separated electronic from vibronic transitions. The electronic transitions are assumed to be due to transitions from the neutral nitrogen donor occupying the three different carbon lattice sites in 6H-SiC into excited states. We determined polarization and the oscillator strengths of these transitions. From the temperature dependence of the electronic transitions we determined the valley-orbit-splitting energy and we demonstrated the influence of compensation. For the different vibronic transitions we determined the Grüneisen constants.

Temperature dependence of IR absorption spectra of the K3Na(CrO4)2 ferroelastic

2013 ◽  
Vol 55 (1) ◽  
pp. 145-149 ◽  
Author(s):  
Yu. E. Kitaev ◽  
T. I. Maksimova ◽  
K. Hermanowicz ◽  
M. Ma̧czka ◽  
J. Hanuza
Keyword(s):  
Temperature Dependence ◽  
Absorption Spectra ◽  
Ir Absorption ◽  
Ir Absorption Spectra

Near-IR Absorption Spectra for the Buckminsterfullerene Anions: An Experimental and Theoretical Study

1992 ◽  
Author(s):  
Del R. Lawson ◽  
Daniel L. Feldheim ◽  
Colby A. Foss ◽  
Peter K. Dorhoug ◽  
C. M. Elliott
Keyword(s):  
Absorption Spectra ◽  
Theoretical Study ◽  
Ir Absorption ◽  
Near Ir ◽  
Ir Absorption Spectra

The Character of Low-Lying Excited States of Mixed-Ligand Metal Carbonyls. TD-DFT and CASSCF/CASPT2 Study of [W(CO)4L] (L = ethylenediamine, N,N'-dialkyl-1,4-diazabutadiene) and [W(CO)5L] (L = pyridine, 4-cyanopyridine)

2003 ◽  
Vol 68 (1) ◽  
pp. 89-104 ◽  
Author(s):  
Stanislav Záliš ◽  
Antonín Vlček ◽  
Chantal Daniel
Keyword(s):  
Excited States ◽  
Substitution Effect ◽  
Electronic Transitions ◽  
Ligand Field ◽  
Metal Carbonyls ◽  
Electron Density Redistribution ◽  
Time Resolved ◽  
Model Complex ◽  
Td Dft ◽  
Time Resolved Infrared Spectroscopy

This contribution presents the results of the TD-DFT and CASSCF/CASPT2 calculations on [W(CO)4(MeDAB)] (MeDAB = N,N'-dimethyl-1,4-diazabutadiene), [W(CO)4(en)] (en = ethylenediamine), [W(CO)5(py)] (py = pyridine) and [W(CO)5(CNpy)] (CNpy = 4-cyanopyridine) complexes. Contrary to the textbook interpretation, calculations on the model complex [W(CO)4(MeDAB)] and [W(CO)5(CNpy)] show that the lowest W→MeDAB and W→CNpy MLCT excited states are immediately followed in energy by several W→CO MLCT states, instead of ligand-field (LF) states. The lowest-lying excited states of [W(CO)4(en)] system were characterized as W(COeq)2→COax CT excitations, which involve a remarkable electron density redistribution between axial and equatorial CO ligands. [W(CO)5(py)] possesses closely-lying W→CO and W→py MLCT excited states. The calculated energies of these states are sensitive to the computational methodology used and can be easily influenced by a substitution effect. The calculated shifts of [W(CO)4(en)] stretching CO frequencies due to excitation are in agreement with picosecond time-resolved infrared spectroscopy experiments and confirm the occurrence of low-lying M→CO MLCT transitions. No LF electronic transitions were found for either of the complexes studied in the region up to 4 eV.

The role of zero-field splitting and π-stacking interaction of different nitrogen-donor ligands on the optical properties of luminescent rhenium tricarbonyl complexes

2021 ◽  
Author(s):  
Plinio Cantero-López ◽  
Yoan Hidalgo-Rosa ◽  
Zoraida Sandoval-Olivares ◽  
Julián Santoyo-Flores ◽  
Pablo Mella ◽  
...  
Keyword(s):  
Excited States ◽  
Coordination Compounds ◽  
Donor Ligands ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Nitrogen Donor Ligands ◽  
Nitrogen Donor ◽  
Π Stacking Interaction ◽  
Rhenium Tricarbonyl

Rhenium tricarbonyl complexes are one of the most important classes of coordination compounds in inorganic chemistry. Exploring their luminescent excited states, lowest singlet (S1), and the lowest triplet (T1), is...

Energy Levels of Core-Excited States and Atomic Oscillator Strengths for Boron and Boron-like Ions (abstract)

2009 ◽  
Author(s):  
Magda A. Rahim ◽  
Beverly Karplus Hartline ◽  
Renee K. Horton ◽  
Catherine M. Kaicher
Keyword(s):  
Excited States ◽  
Energy Levels ◽  
Oscillator Strengths

Study of the Infrared Absorption Spectra of Some Pyridine Derivatives-Iodine Complexes

1976 ◽  
Vol 30 (2) ◽  
pp. 200-204 ◽  
Author(s):  
F. M. Abdel Kerim ◽  
F. Abou El Fotouh
Keyword(s):  
Complex Formation ◽  
Absorption Spectra ◽  
Infrared Absorption ◽  
Ir Absorption ◽  
Pyridine Derivatives ◽  
Thermodynamic Constants ◽  
Ir Absorption Spectra ◽  
Infrared Absorption Spectra ◽  
The Stability ◽  
Iodine Complexes

The ir absorption spectra of some pyridine derivatives-iodine complexes were measured in the region 400 to 1400 cm−1 and the results are discussed. The effect of complex formation on the intensities of some of the bands was investigated. The thermodynamic constants of these complexes were calculated. It was found that the stability of the complex depends to a large extent on the electronegativity as well as the position of the substituent on the pyridine nucleus. The structures of formed complexes are discussed.

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