Theoretical simulations of the He79Br2 B, v=8←X, v″=0 excitation spectrum: Spectroscopic manifestation of a linear isomer?

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Path integral Monte Carlo simulation of the absorption spectra of an Al atom embedded in helium J. Chem. Phys. 123, 134319 (2005) Helium clusters doped with electronically excited atomic and molecular helium anions He * − and He * − 2 at T = 0.4 K are studied by means of path integral Monte Carlo calculations. Geometry and energetics of the systems with up to 32 solvating He atoms are characterised. The interactions between the anions and the neutral He atoms have been described by fitting previously reported ab initio points to analytical expressions. The He N -He * − clusters with N > 6 display a structure defined by a bipyramid which completely solvates the atomic anion, whereas the rest of surrounding He atoms form a dimple around that initial cage. On the contrary, the structures observed for the He N -He * − 2 clusters clearly show the dopant located outside the helium droplet, thereby confirming the heliophobic character of He * − 2 . C 2015 AIP Publishing LLC. [http://dx

Section: Discussionmentioning

confidence: 99%

A configurational study of helium clusters doped with He∗− and He2∗−

Rodríguez‐Cantano

González‐Lezana

Villarreal

et al. 2015

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“…The higher energy feature was later attributed to rovibronic transitions of a linear He¯7 9 Br 2 (X,vЉϭ0) isomer to vibrationally excited He¯7 9 Br 2 (B,vЈϭ8) intermolecular levels. 27,28 …”

Section: Methodsmentioning

confidence: 99%

“…25,26 Subsequent high-level theoretical calculations of the He¯Br 2 spectra 27,28 provide strong evidence that the higher energy He¯Br 2 band can be attributed to transitions of a linear He¯Br 2 (X,vЉϭ0) isomer to He¯Br 2 (B,vЈ) states with intermolecular vibrational excitation. 27,28 The initial simulations of the higher energy He¯ICl feature 26 were undertaken using rigid rotor models. 29,30 These simulations consistently underpredicted the number of rotational lines observed in the experimental spectrum, especially at higher transition energies in the band.…”

Section: Introductionmentioning

confidence: 99%

Combined experimental/theoretical investigation of the He+ICl interactions. I. Rovibronic spectrum of He⋯ICl complexes in the ICl B–X, 3–0 region

McCoy

Darr

Boucher

et al. 2004

Transitions of two different stereoisomers of the He...ICl(X,v" = 0) weakly bound complex, one with a T-shaped orientation and another that is most likely linear, have been observed in laser-induced fluorescence experiments performed in the ICl B-X region. Here we present experimental and theoretical results aimed at confirming the previous assignments and at gaining additional insights into the He+ICl interactions. High resolution action spectra were recorded in the same region to identify those features that could be attributed to transitions of the He...I35Cl(X,v" = 0) isomers and not to higher-order complexes, Hen...I35Cl, where n > or = 2, or I37Cl containing species. Calculations of the rovibronic spectra of the He...I35Cl complexes in the ICl B-X, 2-0 and 3-0 regions were performed using an ab initio potential energy surface for the He+ICl(X,v" = 0) ground state and two different pairwise additive potentials for the He+ICl(B,v' = 2,3) excited states. The rotation-vibration energies and wave functions for the He cdots, three dots, centered I35Cl complexes were obtained for all bound states with total angular momentum J < 10 using both of these potentials. Electronic spectra were generated using these results, assuming that the transition moment lies along the ICl bond and is not perturbed by the presence of the helium atom. The calculations qualitatively reproduce the He cdots, three dots, centered I35Cl action spectrum and strongly support the previous assignments. The calculations also indicate that some of the spectral congestion observed near the linear band may be attributed to transitions of the linear isomer to multiple intermolecular levels in the excited state. Coriolis coupling strongly mixes He cdots, three dots, centered ICl(B,v') states with rotational excitation, making simulations and assignments of the linear band observed in the experimental spectrum difficult.

“…The higher-energy features were originally assigned as transitions of the T-shaped complexes to excited state levels of the He¯Br 2 (B,vЈ) complex with at least one quanta of intermolecular vibrational excitation. Subsequent theoretical predictions 11 indicate that the higher-energy features are more likely that of a separately stabilized He¯Br 2 (X) complex with an equilibrium linear geometry to excited state levels with intermolecular vibrational excitation.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic observation of the preferentially stabilized, linear He⋯ICl(X 1Σ+) complex

Bradke

Loomis

2003

Stabilization and rovibronic spectra of the T -shaped and linear ground-state conformers of a weakly bound raregas-homonuclear dihalogen complex: He Br 2He 79 Br 2 B,v=8←X,v ″ =0 excitation spectrum: Ab initio prediction and spectroscopic manifestation of a linear isomer Spectroscopic features attributed to rovibronic transitions from both the T-shaped and linear He¯I 35 Cl(X) and He¯I 37 Cl(X) ground-state complexes have been recorded in the ICl B 3 ⌸ 0ϩ -X 1 ⌺ ϩ , 2-0 and 3-0 spectral regions using laser-induced fluorescence spectroscopy. Experiments performed using varying expansion conditions indicate that the He¯I 35,37 Cl(X) complex with a linear equilibrium orientation lies lower in energy than the separately localized T-shaped isomer even though the transition energies of the T-shaped and linear complexes are shifted by ϳ3.5 and ϳ14 cm Ϫ1 to higher energy than the I 35,37 Cl B -X band origins, respectively. Based on comparison with the excited state theoretical predictions of Waterland et al. ͓J. Chem. Phys. 92, 4261 ͑1990͔͒, estimates of the binding energies for the ground state T-shaped and linear He¯I 35 Cl(X) complexes are 17 and 21 cm Ϫ1 , respectively, in qualitative agreement with the recently published predictions of 15.2 and 18.3 cm Ϫ1 obtained using high level ab initio theory for the ground state potential energy surface ͓J. Chem. Phys. 117, 7017 ͑2002͔͒.