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.
Laser Spectroscopy of the CCO Radical in the 0.77-μm Region: Analysis of theÃ(020)κ3Π andÃ3Πi(001) States
The A(020)kappa3Pi-X3Sigma-(000) and A3Pii(001)-X3Sigma-(000) bands of the CCO radical have been investigated by laser spectroscopy with two types of tunable laser system. An analysis was made simultaneously for both the bands to establish line assignments and determine molecular constants for both the A(020) and A(001) states. A coupling constant between these two states was also determined by assuming the interaction to be of Fermi type.
A reinvestigation of the NO3 1492 cm-1 band
Ishiwata et al. [J. Chem. Phys. 82, 2196 (1985)] have recently observed an infrared diode laser spectrum of NO3 in the 1492 cm−1 region and have assigned it to the ν3 band in the X2A’2 state. However, some of the derived constants such as the Coriolis coupling and spin–rotation constants did not conform well with expected values. In the present study, the observation was extended so as to take combination differences, which led us to revise the previous assignment slightly and to remove all the anomalies in the lower (i.e., ground) state. A most important result of the present study is that a spin–orbit interaction constant aeff‖〈Lz〉‖ =0.17 cm−1 is indispensable to explain the spin splitting observed for the upper state. The first‐order Coriolis coupling constant of the upper state (ζ=0.19) remains essentially the same as in the previous study and differs considerably from the value calculated for the ν3 state (ζ=0.7). Possible explanations of these data are discussed in some detail to obtain more inform...