FA(Ga+,In+,Tl+) tunable laser activity and interaction of halogen atoms (F,Cl,Br,I,At) at the () surface of KCl crystal: ab initio calculations

Shalabi, A.S.; El-Essawy, T.F.; Assem, M.M.; Abdel-Aal, S.; Mahdy, A.M. El

doi:10.1016/s1567-1739(01)00071-2

Cited by 13 publications

(4 citation statements)

References 27 publications

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“…Exciton band E X , F band E F , E X − E F and E X − E Y for twelve alkali halides have been reported by Malghani and Smith [39] and for LiH and LiF by Shalabi et al [40]. The dependence of the Glasner-Tompkins relation on the dopant cation and surface coordination number (flat, edge and corner) of MgO, KCl and AgBr has also been reported by Shalabi et al [41]. However no attempts have been made to clarify the dependence of the Glasner-Tompkins relation on Ag dopant at the low-coordination (100) and (110) surface sites of KCl and KBr.…”

Section: Glasner-tompkins Relationmentioning

confidence: 61%

The role of F A1:Ag+ defects in laser light generation and coadsorption of CO and halogen atoms at the KCl and KBr surface sites. First principles calculations

Abdelrazik¹,

Shalabi²

2007

Open Physics

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F A1 :Ag+ color center at the low coordination (100) and (110) surface sites of KCl and KBr thin films play an important role in providing tunable laser oscillation and adsorbatesubstrate interactions. Double-well potentials at this site are investigated using ab initio molecular electronic structure calculations. The calculated Stokes shifted (optical transition bands), opticaloptical conversion efficiencies, the probability of orientational destruction, exciton (energy) transfer and Glasner-Tompkins empirical rule suggest that laser light generation is sensitive to (i) the lattice anion, (ii) the coordination number of surface ions, and (iii) the choice of the basis set centered on the anion vacancy. The adsorbate-substrate interactions were found to be dependent on the electronegativity of the adatom and on the lattice anion. Optimised geometries and the coadsorption of CO and (F, Cl, Br, I) on KCl and KBr (100) crystals are presented. Calculated chemisorption energies for CO on the (halogen atom/defect free sites of KCl and KBr (100) crystals) showed that the coadsorption of halogen atom tends to block other adsorbate-substrate interactions at the nearest neighbour sites. Thus if halogen atom coverage increases, the CO prefers to be adsorbed on the K + site of the KCl and KBr (100) surfaces and on KBr relative to KCl.

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Section: Glasner-tompkins Relationmentioning

confidence: 61%

The role of F A1:Ag+ defects in laser light generation and coadsorption of CO and halogen atoms at the KCl and KBr surface sites. First principles calculations

Abdelrazik¹,

Shalabi²

2007

Open Physics

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“…Exciton band E X , F-band E F , (E X − E F ) and <(E X − E F )> values for twelve alkali halides have been reported by Malghani and Smith [30] and for LiH and LiF by Shalabi et al [31]. The dependence of the Glasner-Tompkins relation on the impurity cation and the surface coordination number (flat, edge and corner) has also been reported for MgO, KCl and AgBr by Shalabi et al [11,32]. However, no attempt has been made to clarify the dependence of the GlasnerTompkins relation on the size of the impurity cation on the (100) surface of LiCl.…”

Section: Glasner-tompkins Relationmentioning

confidence: 66%

“…A laser-suitable defect should have relaxed excited states deep below the conduction band of the perfect crystal [11][12][13]. To examine this issue, we consider the band structure of the LiCl surface (i.e., the positions of the one-electron defect levels with respect to the perfect surface bands).…”

Section: Optical-optical Conversionmentioning

confidence: 99%

“…Ab initio calculations of laser light generation at the ionic crystal surface are still lacking, and until recently the potential of F A1 :Ga + , Au + , and Ca 2+ center systems to supply useful laser action at the (100) surface of LiCl has been ignored [11][12][13]. We have therefore carried out a fairly extensive set of ab initio calculations in an attempt to examine the role of cationic radii of the doping cations Ga + , Au + , Ca 2+ , and Sr 2+ in laser light generation at the (100) surface of LiCl.…”

Section: Introductionmentioning

confidence: 99%

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Role of cationic size in the optical properties of the LiCl crystal surface: theoretical study

et al. 2011

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The size of the cations (either Ca(2+), Sr(2+), Ga(+), or Au(+)) at the F(A1)-type color centers on the (100) surface of LiCl crystal plays an important role in the optical properties of this surface. In this work, double-well potentials at this surface were investigated using ab initio quantum mechanical methods. Quantum clusters were embedded in simulated Coulomb fields that closely approximate the Madelung fields of the host surface, and the ions that were the nearest neighbors to the F(A1) site were allowed to relax to equilibrium. The calculated Stokes-shifted optical transition bands, optical-optical conversion efficiency, and relaxed excited states of the defect-containing surface, as well as the orientational destruction of the color centers, recording sensitivity, exciton (energy) transfer, and the Glasner-Tompkins empirical relation were all found to be sensitive to the size of the dopant cation.

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Theoretical study of laser light generation and color image formation:F_A1:Cs⁺andF_A2:Li⁺centers at the low coordination (100) and (110) surfaces of AgCl and AgBr

Shalabi

Kamel

Ammar

2005

Int J of Quantum Chemistry

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ABSTRACT:The F A1 :Cs ϩ and F A2 :Li ϩ color centers at the low coordination (100) and (110) surfaces of AgCl and AgBr play important roles in laser light generation and color image formation. Double-well potentials at these surfaces are investigated by using ab initio calculations. Quantum clusters were embedded in the simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces, and ions that are the nearest neighbors to the F A Ϫ defect site are allowed to relax to equilibrium. The calculated Stokes shifts suggest that laser light generation is sensitive to the simultaneous effects of the vibrational coupling mode, the impurity cation, the coordination number of the surface ion, the lattice anion, and the choice of the basis set centered on the anion vacancy. An attempt has been made to explain these effects in terms of Madelung potential, electron affinity, and optical-optical conversion efficiency. All relaxed excited states of the defect-containing surfaces are deep below the lower edges of the conduction bands of the ground-state defect-free surfaces, suggesting that the F A (I):Cs ϩ and F A (II):Li ϩ centers are suitable laser defects. The dependence of orientational destruction, recording sensitivity, and exciton (energy) transfer on the empty cation; the coordination number of the surface ion; and the lattice anion is clarified. The Glasner-Tompkins empirical rule was generalized to include the impurity cation and the coordination number of the surface ion. As far as color image formation is concerned, the supersensitizer was found to increase the sensitizing capabilities of two primary dyes in the excited states by increasing the relative yield of quantum efficiency. The (110) surfaces of AgBr and AgCl were more sensitive than the corresponding (100) surfaces, and AgBr thin film was found to be more sensitive than that of AgCl. On the basis of quasi-Fermi levels, the difference in the sensitizing capabilities between the examined dyes in the excited states is determined.

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FA(Ga+,In+,Tl+) tunable laser activity and interaction of halogen atoms (F,Cl,Br,I,At) at the () surface of KCl crystal: ab initio calculations

Cited by 13 publications

References 27 publications

The role of F A1:Ag+ defects in laser light generation and coadsorption of CO and halogen atoms at the KCl and KBr surface sites. First principles calculations

The role of F A1:Ag+ defects in laser light generation and coadsorption of CO and halogen atoms at the KCl and KBr surface sites. First principles calculations

Role of cationic size in the optical properties of the LiCl crystal surface: theoretical study

Theoretical study of laser light generation and color image formation:F_A1:Cs⁺andF_A2:Li⁺centers at the low coordination (100) and (110) surfaces of AgCl and AgBr

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FA(Ga+,In+,Tl+) tunable laser activity and interaction of halogen atoms (F,Cl,Br,I,At) at the () surface of KCl crystal: ab initio calculations

Cited by 13 publications

References 27 publications

The role of F A1:Ag+ defects in laser light generation and coadsorption of CO and halogen atoms at the KCl and KBr surface sites. First principles calculations

The role of F A1:Ag+ defects in laser light generation and coadsorption of CO and halogen atoms at the KCl and KBr surface sites. First principles calculations

Role of cationic size in the optical properties of the LiCl crystal surface: theoretical study

Theoretical study of laser light generation and color image formation:FA1:Cs+andFA2:Li+centers at the low coordination (100) and (110) surfaces of AgCl and AgBr

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Theoretical study of laser light generation and color image formation:F_A1:Cs⁺andF_A2:Li⁺centers at the low coordination (100) and (110) surfaces of AgCl and AgBr