Probing the structures of neutral boron clusters using infrared/vacuum ultraviolet two color ionization: B11, B16, and B17.

The structures of neutral boron clusters, B(11), B(16), and B(17), have been investigated using vibrational spectroscopy and ab initio calculations. Infrared absorption spectra in the wavelength range of 650 to 1550 cm(-1) are obtained for the three neutral boron clusters from the enhancement of their near-threshold ionization efficiency at a fixed UV wavelength of 157 nm (7.87 eV) after resonant absorption of the tunable infrared photons. All three clusters, B(11), B(16), and B(17), are found to possess planar or quasi-planar structures, similar to their corresponding anionic counterparts (B(n) (-)), whose global minima were found previously to be planar, using photoelectron spectroscopy and theoretical calculations. Only minor structural changes are observed between the neutral and the anionic species for these three boron clusters.