Rydberg states of small NaArn* clusters

Rhouma, Mounir Ben El Hadj; Lakhdar, Z. Ben; Berriche, H.; Spiegelman, Fernand

doi:10.1063/1.2229210

Cited by 38 publications

(55 citation statements)

References 75 publications

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“…The small number of accessible parameters does not allow a full exploration of the phase space of the charge-separated system. More sophisticated theoretical approaches, 16,17,42 including higher excited states, through ab initio methods, are necessary for a complete understanding of the spectral features.…”

Section: Discussionmentioning

confidence: 99%

“…The use of a "simple" DIM method is preferred as a first approach to the problem in spite of the complexity of the interaction of the excited sodium atom with a rare gas surrounding. 16,17 Accurate ground and excited state potential energy curves extracted from spectroscopic data for all the Na · RG diatomics are currently available, and our simulations are also a test of their validity in the matrix context. On the basis of these Na · RG pair-potentials, the MD calculations permit us to follow the internal motion of the trapped species within the lattice of the host matrix in both the ground and excited states.…”

Section: Introductionmentioning

confidence: 99%

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Investigations of the Optical Spectroscopy of Atomic Sodium Isolated in Solid Argon and Krypton: Experiments and Simulations.

et al. 2009

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The absorption spectra of thin film samples, formed by the codeposition of sodium vapor with the rare gases have long been known to consist of complex structures in the region of the atomic sodium "yellow-doublet" lines. The photophysical characteristics of the associated luminescence (excitation/emission) spectra, indicate strong interaction between the excited P state Na atom and the rare gases (Ar, Kr, and Xe) used as host solids. This system is reinvestigated with new experimental spectroscopic results and molecular dynamics (MD) calculations. The so-called "violet" site in Ar and Kr has been produced by laser excitation of thermally deposited samples. The simulation of the "spray-on" deposition of thin films enables identification of tetravacancy (tv) sites of isolation for ground-state atomic sodium in Ar while in Kr this site is found in addition to single vacancy (sv) occupancy. Various cubic symmetry sites were taken into account to simulate absorption and emission spectra using accurate interaction potentials for the Na · RG diatomics. The wellknown 3-fold splitting in absorption, attributed to the Jahn-Teller effect, was very well reproduced but the simulated spectra for all the sites considered are located in the low energy region of the experimental bands. The evolution of the excited state Na atom is followed revealing the nature and symmetry of the sites that are transiently occupied. Consistent with the large Stokes shift observed experimentally, there is an extensive rearrangement of the lattice in the excited state with respect to the ground state. Combining all the experimental and theoretical information, an assignment of experimental violet, blue, and red absorption features is established involving single vacancy, tetravacancy, and hexavacancy sites, respectively, in Ar and Kr.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigations of the Optical Spectroscopy of Atomic Sodium Isolated in Solid Argon and Krypton: Experiments and Simulations.

et al. 2009

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“…Kr n and Rb ? Ar n small clusters [16][17][18] and we have determined their equilibrium structures. Martyna et al [10] have studied the LiXe n and CsXe n clusters using the path integral calculations at a temperature of 50 K. Boatz et al [9] studied the NaAr n clusters and analyzed the shifts corresponding to the 3p excited states of sodium in an argon matrix.…”

Section: Introductionmentioning

confidence: 99%

“…It was shown, for Li ? Xe n , that n = 4, 6,10,14,16,18,20,22,24, 26, 28 and 30 are the most stable structures. …”

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confidence: 99%

Structure and Stability of the Li+Xen and LiXen Clusters

et al. 2014

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We have studied the structure and stability of the ionic Li ? Xe n and neutral LiXe n (n = 1-35) small clusters. The potential energy surface of the ionic cluster is described using additive potentials, which represent the pair interactions taken from the best available coupled cluster ab initio calculations. The V Li ? Xe and V Xe-Xe potentials have been fitted by Tang and Toennies and Lennard-Jones (LJ) forms, respectively. The structure of LiXe n neutral clusters have been investigated using a model potential and ab initio calculations. We have used the Li ? Xe potential in its ground state and fitted to the Tang and Toennies formula. The LiXe n optimized geometry is, then, used for one electron self consistent filed calculation of the only alkali valence electron interacting with the Li ? Xe n cluster. In order to determine the geometry of Li ? Xe n and LiXe n clusters and their isomers, the potential energy surface has been explored by the Monte Carlo basin Hopping method. Their relative stability was studied by evaluating the energy and the energy differences as function of number n of Xenon atoms in clusters. It was shown, for Li ? Xe n , that n = 4, 6,10,14,16,18,20,22,24, 26, 28 and 30 are the most stable structures.

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“…Such a methodology was found to produce results with high accuracy in various systems, including alkali diatomics, K 2 (Magnier et al 1996(Magnier et al , 2004, and metal-rare gas systems (El Hadj Ben Rhouma et al 2002;Spiegelman et al 2002) including potassium. We present theoretical calculations of the unified line profile of this alkali perturbed by molecular hydrogen with an emphasis on properties of the line satellite.…”

Section: Introductionmentioning

confidence: 99%

Study of the K-H${_2}$ quasi-molecular line satellite in the potassium resonance line

Allard

Spiegelman

Kielkopf

2007

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Context. The optical spectra of L and T-type dwarfs exhibit a continuum dominated by the far wings of the absorption profiles of the Na 3s-3p and K 4s-4p doublet perturbed by molecular hydrogen and helium. The presence of a broad absorption feature in the blue wing of the K 4s-4p doublet may be attributed to the K-H 2 quasi-molecular line satellite as we predicted in a previous work. Aims. The position of the predicted line satellite was not in good agreement with the observed feature. This was a motivation to compute new interaction potentials and corresponding profiles. Methods. New molecular potentials for K-H 2 were computed using a valence pseudopotential with Gaussian orbitals on potassium, for an H 2 molecule assumed to be in its ground state. A quasi-full three-electron multireference calculation agrees very well with available spectroscopic data. The potentials and radiative dipole transition moments were input data for a unified spectral line shape evaluation of the complete K resonance line profile. Results. We show that these improved potentials now predict a line satellite at the position that is observed in late brown dwarf spectra. The existence, shape and strength of this feature is found to depend strongly on temperature, as well on the abundance ratio of potassium and sodium. Conclusions. The structure of the continuum in brown dwarf spectra from 500 to 1000 nm is determined by radiative collisions of alkali atoms with H 2 molecules. We conclude that the sensitivity of the spectrum to temperature, pressure and abundances is a tool for determining basic parameters of brown dwarf atmospheres, provided that the physics underlying its formation is described well.

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Rydberg states of small NaArn* clusters

Cited by 38 publications

References 75 publications

Investigations of the Optical Spectroscopy of Atomic Sodium Isolated in Solid Argon and Krypton: Experiments and Simulations.

Investigations of the Optical Spectroscopy of Atomic Sodium Isolated in Solid Argon and Krypton: Experiments and Simulations.

Structure and Stability of the Li+Xen and LiXen Clusters

Study of the K-H${_2}$ quasi-molecular line satellite in the potassium resonance line

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