Experimental and theoretical study of the electronic spectrum of the BAr2 complex: Transition to the excited valence B(2s2p2 2D) state

Abstract

The 2s2p 2 2 D←2s 2 2p 2 P valence transition in the BAr 2 cluster is investigated in a collaborative experimental and theoretical study. Laser fluorescence excitation spectra of a supersonic expansion of B atoms entrained in Ar at high source backing pressures display several features not assignable to the BAr complex. Resonance fluorescence is not observed, but instead emission from the lower 3s state. Size-selected fluorescence depletion spectra show that these features in the excitation spectrum are primarily due to the BAr 2 complex. This electronic transition within BAr 2 is modeled theoretically, similarly to our earlier study of the 3s←2p transition ͓M. H. Alexander et al., J. Chem. Phys. 106, 6320 ͑1997͔͒. The excited potential energy surfaces of the fivefold degenerate B(2s2 p 2 2 D)state within the ternary complex are computed in a pairwise-additive model employing diatomic BAr potential energy curves which reproduce our previous experimental observations on the electronic states emanating from the B( 2 D)ϩAr asymptote. The simulated absorption spectrum reproduces reasonably well the observed fluorescence depletion spectrum. The theoretical model lends insight into the energetics of the approach of B to multiple Ar atoms, and how the orientation of B p-orbitals governs the stability of the complex.

Accurate ab Initio Structural Parameters of the Diatomic and Triatomic van der Waals Molecules 11BNg (X2Π, A2Σ+) and 11BNg2 (X̃2B1), Ng = 4He, 20Ne, 40Ar, 84Kr, and 132Xe

“…No experimental data are available save certain observations on the existence of excited states of BNe 2 33 and BAr 2 . 11,34 On the theoretical side (nonab initio) calculations predict AE 0 = 53.19 ± 0.3 and 295 ± 0.21 cm −1 for BNe 2 33 and BAr 2 , 11,34 respectively. The following conclusions can be drawn going through the numerical results of Table 5: Xe 2 , respectively.…”

Optical properties of atomic boron in rare gas matrices: An ultraviolet-absorption/laser induced fluorescence study with ab initio and diatomics-in-molecules molecular dynamics analysis

“…10 Finally, the B(2s2p 2 ) 2 D state excitation was succesfully added to theory in a BAr 2 study. 11 The experimental blueshifts for BAr and BAr 2 are 230 and 420 cm Ϫ1 , respectively. 9 Of particular interest is the 108 cm Ϫ1 barrier in the BAr double well B 2 ⌺ ϩ potential at internuclear separation corresponding to the ground state minimum.…”

Absorption Spectroscopy, a Tool for Probing Local Structures and the Onset of Large-Amplitude Motions in Small KArn Clusters at Increasing Temperatures

“…For instance, the microsolvation of aromatic molecules was pioneered in the group of Leutwyler and further developed elsewhere. − The second motivation appeared in theoretical works, where the chromophore spectroscopy is proposed as a sensitive probe of the structure and phase (liquid or solid) of the rare-gas moiety that interacts with the chromophore. This point of view appeared in a series of works where the chromophore is a single alkali, − alkaline earth, , or boron atom. The photoabsorption spectrum of Ca in CaAr n cluster was also proposed as a way to prove the relaxation dynamics of these clusters when placed out of equilibrium …”