Near-infrared diode laser spectroscopy of free radicals.
Spectroscopic results on the radicals HCSi, CCO, and FeC obtained by studying in detail energy level structures using 0.8 microm diode laser system are reported. Of these radicals, the CCO radical was investigated mainly using Fabry-Perot type diode lasers with inconvenient mode gaps in the early stage of our near-infrared diode laser spectroscopic study of free radicals, and on the other hand, the FeC and HCSi radicals were studied using an external cavity diode laser. For the FeC radical, which is an interesting radical composed of an iron atom having 3d electrons, information on spin-orbit interaction between the triplet electronic ground state and a low-lying singlet electronic excited state is reported somewhat in detail. For the HCSi and CCO radicals, spectral particularities produced by a Renner-Teller interaction and a spin-orbit interaction are described for their high-resolution spectroscopic interest.
Near-Infrared Diode Laser Spectroscopy of the Nitrogen Molecule in Rydberg State: Analysis of thec1Πu−a″1Σg+,v= 1–0 Band
Abstract A new singlet-singlet absorption band between Rydberg states of the nitrogen molecule was studied by near-infrared diode laser spectroscopy in the 1.3 μm region. An analysis was made for the band to establish line assignments and determine molecular parameters for both the lower and the upper vibronic states. As a result of the analysis, this band was assigned to the c 1 Π u –a ″ 1 Σ g + , v = 1–0 band. The anomaly of the Λ-type doubling structure in the c 1 Π u ( v = 1) state was discussed in connection with the interaction with the b ′ 1 Σ u + (v = 4) state. The predissociation in the c 1 Π u ( v = 1) state was also discussed relating with the line broadening observed.
Near-infrared diode laser spectroscopy of the nitrogen molecule in Rydberg states
Two electronic bands of the nitrogen molecule were observed by near‐infrared diode laser absorption spectroscopy around the 1.3 μm region. One band was assigned to the transition from the E 3Σ+g(v‘=0) to D 3Σ+u(v’=0) state. Both states were previously assigned as Rydberg states with an s‐ or p‐electron, and an N+2 X 2Σ+g core. Fine structure constants of these states were determined for the first time. The second band looked as if it belonged to a doublet system of the molecular ion, but it turned out to be that of the neutral when the doublet structure was resolved into triplet components by means of sub‐Doppler saturation spectroscopy. This band was also assigned as a 3Σ+−3Σ+ transition and was tentatively assigned to a vibrational hot band of the D–E transition based on the rotational constants, lifetime, transition dipole moment, and systematic line broadening due to predissociation.