25 research outputs found
Electron traps in solid Xe
Correlated real-time measurements of thermally stimulated luminescence and exoelectron emission from solid Xe pre-irradiated with an electron beam were performed. The study enabled us to distinguish between surface and bulk traps in solid Xe and to identify a peak related to electronically induced defects. The activation energy corresponding to annihilation of these defects was estimated by the following methods: the method of different heating rates, the initial-rise method, and the curve cleaning technique with fitting of the thermally stimulated luminescence glow curve
Matrix-isolation FTIR study of azidoacetone and azidoacetonitrile
Azidoacetonitrile (N₃CH₂CN) and azidoacetone (N₃CH₂COCH₃) were studied by matrix-isolation FTIR spectroscopy in solid neon, argon and nitrogen. The IR spectra calculated using the density fuctional theoretical method are discussed in comparison with the experimental data. Significant broadening of the recorded azide bands indicate an awkward fit of these compounds into the solid environment. The strongest absorption is observed for both compounds in the regions of asymmetric and symmetric stretches of the N₃ azide group. Strong band splittings in the N₃ asymmetric stretch region can be most likely explained by very strong Fermi resonances with the CN stretch and combinations and overtones of the numerous lower frequency vibrational modes
Deposition of mass-selected ions in neon matrices: CS₂⁺ and C₆F₆⁺
Infrared and visible absorption spectra and laser-induced fluorescence (LIF) and excitation spectra are obtained for several simple cations deposited from a mass-selected ion beam. In the present preliminary study we demonstrate successful and clean mass selection by presenting spectra of samples obtained by depositing the isotopic ³⁴S¹²C³²S⁺ ion in natural isotopic abundance, and analyzing its spectrum. Spectra of C₆F₆⁺ deposited from a 20 eV ion beam exhibit quite different inhomogeneous line profiles, suggesting that even the relatively low kinetic energy results in considerable damage to the solid. Analysis of the spectra indicates that the Jahn–Teller-distorted vibrational structure in the doubly degenerate ground state of C₆F₆⁺ is strongly perturbed in the newly formed sites, which are presumably of lower symmetry. A 33–46 cm−1 splitting of the origin and other totally symmetric bands in emission is tentatively attributed to the spin–orbit splitting in the ²E₁g ground state
PROBING THE EVOLUTION OF BONDING IN BERYLLIUM CLUSTERS; SPECTROSCOPIC IDENTIFICATION OF Be
Author Institution: Department of Chemistry, Emory University, Atlanta GA 30322; 418 Vista Quinta, Newport Beach, CA 92660The beryllium tetramer has been observed for the first time utilizing pulsed laser ablation of Be metal followed by supersonic expansion into vacuum. The bonding characteristics are probed using electronic spectroscopy by detecting 1+1' REMPI generated ions and also by recording laser induced fluorescence spectra. A vibrational band progression in the UV region is observed and analyzed confirming the tetrahedral symmetry of the ground state. A time of flight mass-spectrometer is used to detect the ions confirming that the new signals have m/z = 36. Each vibrational band appears doubled which we attribute to Jahn-Teller distortion in the excited state. From the analysis of the rotationally resolved spectra we have determined that the Be-Be bond length in the ground electronic state contracts significantly compared with Be illustrating a dramatic change in bonding characteristic. New ab initio calculations on Be are also described in order to help interpret the experimental data. The ionization energy of Be has also been measured using photo-ionization efficiency curves and compared with theory