The origins of the colours of natural yellow, blue, and green sapphires

1972 ◽  
Vol 25 (7) ◽  
pp. 1371 ◽  
Author(s):  
J Ferguson ◽  
PE Fielding
Keyword(s):  
Temperature Dependence ◽  
Absorption Spectra ◽  
Excited States ◽  
Exchange Parameter ◽  
Nearest Neighbour ◽  
Electronic Excitations ◽  
Heisenberg Exchange ◽  
Synthetic Crystals

An analysis of the absorption spectra of natural yellow sapphires shows that the absorption is due to single Fe3+ ions and pairs of ions Fe3+-O2--Fe3+. Assignments of all levels from the 4G, 4P, and 4D have been made as well as four simultaneous electronic excitations of a pair of ions. The temperature dependence of the intensity of the pair absorption shows that one pair is mainly involved, probably the fourth- nearest neighbour pair. The value of the Heisenberg exchange parameter (J Sa. Sb) lies in the range 30-40 K. Estimates of this parameter for various excited states have been made. Synthetic yellow sapphires have spectra which duplicate the natural specimens. Blue and green natural sapphires have, in addition to the bands present in the spectra of yellow sapphires, spectra with bands at 17800 (┴C), 14200 (//c), 11500 (┴C), and 10000 om-1 (//c). The first two can be linked to Fe,Ti pairs and the evidence favours the nearest neighbour pair Ti4+-O2?Fe2+ for the 17800 cm-1 band and possibly the first neighbour pair for the 14200 cm-1 band. The second two can be produced in synthetic crystals by growth from fluoride-containing flux and the evidence supports an explanation involving second-nearest neighbour pairs Fe2+- O2--Fe3+ for the 11500 cm-1 absorption and first neighbours for the 10000 om-1 absorption.

Electronic absorption, fluorescence and polarisation spectra of α,β-diamino-9,10-anthraquinones and their interpretation by the method of configuration analysis

1982 ◽  
Vol 47 (10) ◽  
pp. 2604-2614 ◽  
Author(s):  
Miloš Nepraš ◽  
Miloš Titz ◽  
Jürgen Fabian ◽  
Bohuslav Gaš
Keyword(s):  
Polyvinyl Alcohol ◽  
Absorption Spectra ◽  
Excited States ◽  
Wavelength Range ◽  
Electronic Absorption ◽  
Frequency Dependent ◽  
Absorption Frequency

On the basis of measurement of absorption frequency-dependent polarisation spectra of fluorescence (APF) and dichroism on oriented polyvinyl alcohol sheets, interpretation has been carried out of absorption spectra of α,β-diamino-9,10-anthraquinones in the wavelength range 250 to 600 nm. Character of the excited states has been investigated by the method of configuration analysis (PPP-CA).

scholarly journals Theoretical Electronic and Rovibrational Studies for Anions of Interest to the DIBs

2013 ◽  
Vol 9 (S297) ◽  
pp. 344-348 ◽  
Author(s):  
R. C. Fortenberry
Keyword(s):  
Excited State ◽  
Excited States ◽  
State Of The Art ◽  
Spectroscopic Constants ◽  
Coupled Cluster ◽  
Electronic Excitations ◽  
Electronically Excited States ◽  
Coupled Cluster Theory ◽  
Electronically Excited ◽  
Enolate Anion

AbstractThe dipole-bound excited state of the methylene nitrile anion (CH2CN−) has been suggested as a candidate carrier for a diffuse interstellar band (DIB) at 803.8 nm. Its corresponding radical has been detected in the interstellar medium (ISM), making the existence for the anion possible. This work applies state-of-the-art ab initio methods such as coupled cluster theory to reproduce accurately the electronic excitations for CH2CN− and the similar methylene enolate anion, CH2CHO−. This same approach has been employed to indicate that 19 other anions may possess electronically excited states, five of which are valence in nature. Concurrently, in order to assist in the detection of these anions in the ISM, work has also been directed towards predicting vibrational frequencies and spectroscopic constants for these anions through the use of quartic force fields (QFFs). Theoretical rovibrational work on anions has thus far included studies of CH2CN−, C3H−, and is currently ongoing for similar systems.

OPTICAL ABSORPTION SPECTRA OF ARSENIC AND PHOSPHORUS IN SILICON

1962 ◽  
Vol 40 (10) ◽  
pp. 1480-1489 ◽  
Author(s):  
J. W. Bichard ◽  
J. C. Giles
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Excited States ◽  
Ground State ◽  
Absorption Lines ◽  
Full Width ◽  
Optical Absorption Spectra ◽  
Phosphorus Impurity ◽  
Line Widths ◽  
Phosphorus In Silicon

The optical absorption spectra of arsenic and phosphorus donor impurities in silicon have been studied under conditions of improved resolution. Absorption lines due to transitions from the impurity ground state to the excited states 2p0, 2p±, 3p0, 3p±, 4p0, 4 p±, and 5p0, and 5p± have been observed at 4.2° K. The relative intensities of some of these absorption lines are compared with existing experimental and theoretical estimates. The contribution of instrumental broadening to the observed line widths is assessed and natural line widths are estimated. The estimates indicate values for the natural line widths which are much less than those previously reported. For phosphorus impurity, the natural line widths are estimated to be less than 0.08 × 10−3 electron volts full width at half-maximum. The possibility of concentration broadening is discussed in connection with the arsenic data.

Temperature dependence of the absorption spectra in CdTe-doped glasses

1999 ◽  
Vol 14 (1) ◽  
pp. 58-63 ◽  
Author(s):  
M L Redígolo ◽  
W A Arellano ◽  
L C Barbosa ◽  
C H Brito Cruz ◽  
C L Cesar ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Absorption Spectra ◽  
Doped Glasses

FRUSTRATED TRANSVERSE ISING MODELS: A CLASS OF FRUSTRATED QUANTUM SYSTEMS

1992 ◽  
Vol 06 (14) ◽  
pp. 2439-2469 ◽  
Author(s):  
P. SEN ◽  
B. K. CHAKRABARTI
Keyword(s):  
Excited States ◽  
Transverse Field ◽  
Ising Models ◽  
Quantum Systems ◽  
Nearest Neighbour ◽  
Competing Interactions ◽  
Annni Model ◽  
Kirkpatrick Model ◽  
Transverse Fields ◽  
Exact Diagonalisation

The analytical and numerical (Monte Carlo and exact diagonalisation) estimates of phase diagrams of frustrated Ising models in transverse fields are discussed here. Specifically we discuss the Sherrington–Kirkpatrick model in transverse field and the Axial Next-Nearest Neighbour Ising (ANNNI) model in transverse field. The effects of quantum fluctuations (induced by the transverse field) on the ground and excited states of such systems with competing interactions (frustration) are also discussed. The results are compared to those available for other frustrated quantum systems.

scholarly journals Excited-states of a rhenium carbonyl diimine complex: solvation models, spin–orbit coupling, and vibrational sampling effects

2017 ◽  
Vol 19 (40) ◽  
pp. 27240-27250 ◽  
Author(s):  
Sebastian Mai ◽  
Hugo Gattuso ◽  
Maria Fumanal ◽  
Aurora Muñoz-Losa ◽  
Antonio Monari ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Excited States ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Implicit Solvation ◽  
Td Dft ◽  
Rhenium Carbonyl ◽  
Solvation Models ◽  
P Absorption

Absorption spectra of [Re(CO)3(imidazole)(phenanthroline)]+ were computed using TD-DFT with QM/MM, frozen-density embedding, and implicit solvation models.

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