Experimental and Theoretical Characterization of the 2²A′–1²A′ Transition of BeOH/D

Abstract

The hydroxides of Ca, Sr, and Ba are known to be linear molecules, while MgOH is quasilinear. High-level ab initio calculations for BeOH predict a bent equilibrium structure with a bond angle of 140.9°, indicating a significant contribution of covalency to the bonding. However, experimental confirmation of the bent structure is lacking. In the present study, we have used laser excitation techniques to observe the 2(2)A'-1(2)A' transition of BeOH/D in the energy range of 30300-32800 cm(-1). Rotationally resolved spectra were obtained, with sufficient resolution to reveal spin splittings for the electronically excited state. Two-color photoionization was used to determine an ionization energy of 66425(10) cm(-1). Ab initio calculations were used to guide the analysis of the spectroscopic data. Multireference configuration interaction calculations were used to construct potential energy surfaces for the 1(2)A', 2(2)A', and 1(2)A" states. The rovibronic eigenstates supported by these surfaces were determined using the Morse oscillator rigid bender internal dynamics Hamiltonian. The theoretical results were in sufficiently good agreement with the experimental data to permit unambiguous assignment. It was confirmed that the equilibrium geometry of the ground state is bent and that the barrier to linearity lies below the zero-point energies for both BeOH and BeOD.

Ab initio study of the neutral and anionic alkali and alkaline earth hydroxides: Electronic structure and prospects for sympathetic cooling of OH−

“…This lead to a large difference between r e (the geometry at the minimum of the potential energy surface) and r 0 (the expectation value of the ground state vibrational wave function), usually measured in experiments. All neutral species have been known to be linear with the exception of BeOH for which the predicted bent structure has recently been confirmed by a experimental study 15 , supported by ab initio calculations. Our calculated bond angle agrees with their results.…”

“…Neutral alkali and alkaline earth hydroxides (MOH) have been extensively studied both theoretically [10][11][12][13][14][15][16][17][18][19][20] and experimentally [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] (see also the reviews of A.Ellis 36 and Gurvitch et al 37 ). The interest lies in the general context of molecular structure and the understanding of the M-O bond.…”

“…The interest lies in the general context of molecular structure and the understanding of the M-O bond. The alkali and heavy alkaline earth (Ca, Sr, Ba) hydroxides are known to exhibit a linear equilibrium geometry while lighter alkaline earth hydroxides are either quasi linear (MgOH) 22 or bent (BeOH) 15 . The linear structure is usually explained by the strong ionic character of the alkali and heavy alkaline earth hydroxides while the more covalent character of the BeOH and MgOH molecules favors a bent structure.…”

Ab initio potential energy surface and vibration‐rotation energy levels of beryllium monohydroxide

“…The ground bending state of the main isotopologue BeOH was calculated to lie just 3 cm −1 below the barrier top. The quasilinearity of the BeOH molecule was only recently confirmed experimentally by Mascaritolo et al…”

The Fourier transform microwave/millimeter-wave spectrum of YOH and YOD (X̃1Σ+Halfen1, Keogh2, Ziurys3 2015Journal of Molecular Spectroscopy2000View full textAdd to dashboardCite

“…High-resolution spectroscopy of alkali and alkaline-earth hydroxide species has been carried out for several decades, beginning with the work of Lide and collaborators [6][7][8][9][10][11][12][13][14][15][16][17][18]. More recently, investigations of aluminum and indium hydroxides have been performed, providing additional insight [19,20].…”