A BaGa4Se7 crystal based pulsed mid-infrared light source with a narrow linewidth in 4-12 µm.

We present a BaGa4Se7 (BGSe) crystal based coherent pulsed light source for high resolution mid-infrared (MIR) spectroscopy in the 4-12 µm region. The all-solid-state system consists of an injection seeded optical parametric generator (OPG) and an optical parametric amplifier (OPA) using two KTiOPO4 crystals. The idler output of OPG-OPA and the fundamental output (1064 nm) of a wavelength stabilized Nd:YAG laser are employed for difference frequency generation of MIR pulses in the BGSe crystal.

High-Resolution Electronic Spectrum of the 1,4,6-Heptatrienyl Radical in the Gas Phase.

We report the gas-phase identification of the 1,4,6-heptatrienyl (CH) radical via its - electronic transition spectrum. The optical absorption spectrum in the 590-630 nm region is recorded using cavity ring-down spectroscopy in combination with a supersonic plasma jet. An analysis of the rotationally resolved origin band spectrum has allowed an accurate determination of spectroscopic constants for both the electronic ground and excited states of this radical.

Gas-Phase Optical Spectra of the Indenyl Radical and Its Quantitative Detection in a Jet-Stirred Reactor.

Resonance-stabilized radicals (RSRs), such as the indenyl radical (CH), are proposed to be initiator radicals in soot inception and growth in hydrocarbon combustion processes, but spectroscopic data for many RSRs are still lacking. In this work, the gas-phase optical absorption spectra of the B̃A-X̃A electronic transition of indenyl were identified in a supersonic indene/argon plasma jet. Spectroscopic parameters, including the transition energy, rotational constants, and upper-state lifetime broadening, were obtained from analysis of the experimental spectra.

High-resolution laser spectroscopy of the trans- and cis-1-vinylpropargyl radicals.

Rotationally resolved spectra of the ÃA-X̃A origin bands for both trans- and cis-conformers of 1-vinylpropargyl radical (1VPR) are experimentally studied. Rotational constants for both ground and electronically excited states are experimentally determined. The stability of the ÃA excited state of the cis-1VPR is found to be higher than that of trans-1VPR, which is likely due to additional π-overlap and increased p electron delocalization in the excited state of cis-1VPR.

High-Resolution Laser Spectroscopic Survey of the HΣ-XΣ Electronic Transition of Si.

Rotationally resolved spectra of the HΣ-XΣ electronic transition bands of Si have been experimentally studied using laser-induced fluorescence in the 380-520 nm range. Si molecules are produced in a supersonically expanding planar plasma by discharging a silane/argon gas mixture. In total, 44 bands belonging to the HΣ-XΣ electronic transition system of the most abundant isotopologue Si are experimentally recorded.