Jerry M. Kramer

Photodissociation of gaseous olefinic cations

An ion cyclotron resonance spectrometer was used to study the wavelength dependence of the photodissociation of cations in propene and several isomeric butenes. Photodissociation onsets were determined and compared with electron impact and thermodynamic values. In all cases the photodissociation onsets were found to be above both the thermodynamic onset and the first excited state of the cation as determined by photoelectron spectroscopy. The onset results were compatible with a photodissociation mechanism that proceeds by initial excitation into the first excited state, followed by dissociation. A large increase in the photodissociation cross section for all the cations studied was observed at [inverted lazy s] 3.7 eV. This increase correlated with the second excited states of all the cations except 1‐butene. Internal excitation of the parent cations was investigated by the addition of inert gas and by changing the electron beam energy. Photodissociation onsets were also found to be valuable in choosing ...

Spectroscopic characterization of ytterbium monohalide emission in a high pressure electrodeless microwave arc discharge

Molecular emission has been observed in high‐pressure electrodeless microwave arc discharges from the monochloride, monobromide, and monoiodide of ytterbium. The vibrational analyses of the electronic transitions in YbBr and YbI represent the first spectroscopic data for these molecules. Emission from the A (2Σ1/2) →X (2Π+) and A (2Π+) and R (2Π3/2) →X (2Σ+) transitions in YbCl have been observed. By analogy with YbF and YbCl, the blue degraded emission in YbBr and YbI has been assigned to the A (2Π1/2) →X (2Σ+) and A (2Π3/2) →X (2Σ+) transitions. The term values for YbBr and YbI are shifted to the red with respect to YbCl by <100 cm−1 and <300 cm−1, respectively, for both transitions. The spin–orbit coupling constants of the A (2Π) state in YbBr and TbI have been determined from the difference in the band origins of the two A→X transitions. The effect of the lanthanide contraction in the ytterbium monohalides has been examined by comparing the ground state vibrational frequencies of the ytterbium monohal...

The detection and characterization of the visible emission spectra of lutetium monochloride, monobromide, and monoiodide

Molecular emission has been observed in high pressure electrodeless microwave arc discharges from the monochloride, monobromide, and monoiodide of lutetium. The vibrational analyses of two electronic transitions in LuCl, LuBr, and LuI represent the first spectroscopic data for these molecules. The Lu monohalide band spectra in the visible are composed of two electronic transitions, which are degraded to the red. These transitions are characterized by long vibrational sequences, centered about Δv =0. The term values for LuBr and LuI are shifted to the red with respect to LuCl by ∼1000 and ∼2500 cm−1, respectively, for both transitions. The vibrational analyses reveal that both the upper and lower state vibrational frequencies of these two transitions are different for all three monohalides. This suggests that four different electronic states are involved in these two transitions. Explanations for these two transitions are sought by analogy with the group III (Sc, Y, and La) monohalides and the isoelectroni...