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 FeC in the 0.8-μm Region: A Simultaneous Analysis of the X3Δi and [3.8]1Δ States
Abstract The near-infrared absorption spectra of the FeC radical have been measured by diode laser spectroscopy in the regions from 11 810 to 13 200 cm −1 . Rotationally resolved 28 new vibronic bands of the 56 Fe 12 C major isotopic species were observed as well as two known bands. Five of them were assigned as the v ′= v ″=0–4 sequence bands in the [13.1] 3 Φ 4 ← X 3 Δ 3 system, six are the v ′= v ″=0–5 sequences in the [13.18]Ω=3← X 3 Δ 2 system, and five were assigned as the v ′= v ″=0–4 sequences in the [13.5]Ω=2← X 3 Δ 1 system. The X 3 Δ 1 state of FeC is reported for the first time but we found that the rotational constant for this state of 56 FeC is very close to that for the X 3 Δ 3 state of 54 FeC. Transitions of the 54 FeC minor isotopic species for the two known bands were thus reinvestigated. For the unclassified 11 new bands, the lower states were assigned as the v =0–3 states in X 3 Δ i . The energy difference between the Ω=2 and 3 sublevels in the X 3 Δ i state could be determined to be 329.8059±0.0005 cm −1 as a results of the analysis of the two of new bands, [12.32]← X 3 Δ 3 v =0 and [12.32]← X 3 Δ 2 v =0 observed near 12 317 cm −1 and 11 987 cm −1 , respectively. Stimulated emission pumping spectra were also recorded near 17 600 cm −1 to examine the low-lying electronic state which had been observed 3460 cm −1 above the X 3 Δ 2 state (K. Aiuchi and K. Tsuji and K. Shibuya, Chem. Phys. Lett. 309, 229–233 (1999)), and it was assigned as the [3.8] 1 Δ state arising from the same configuration as that of X 3 Δ i (…3π 4 1δ 3 9σ 1 ). In addition, the v =0–0 and 1–1 bands of the [16.2]Ω=3←[3.8] 1 Δ system were observed by near-infrared diode laser spectroscopy. The lower state combination differences were calculated for the possible sets of the energy levels in the X 3 Δ i and [3.8] 1 Δ states with v =0–5 by using the present result and the other spectroscopic data reported. A simultaneous analysis was carried out by using the combination differences to determine the molecular constants for the X 3 Δ i and [3.8] 1 Δ states as well as the off-diagonal spin–orbit interaction terms. The [13.18]Ω=3 state and the [13.5]Ω=2 state were concluded to be other two spin sublevels for the [13.1] 3 Φ 4 state and the [16.2]Ω=3 state was assigned as an isoconfigurational 1 Φ state.
Protective effect of ginsenoside Re on acute gastric mucosal lesion induced by compound 48/80
The protective effect of ginsenoside Re, isolated from ginseng berry, against acute gastric mucosal lesions was examined in rats with a single intraperitoneal injection of compound 48/80 (C48/80). Ginsenoside Re (20 mg/kg or 100 mg/kg) was orally administered 0.5 h prior to C48/80 treatment. Ginsenoside Re dose-dependently prevented gastric mucosal lesion development 3 h after C48/80 treatment. Increases in the activities of myeloperoxidase (MPO; an index of neutrophil infiltration) and xanthine oxidase (XO) and the content of thiobarbituric acid reactive substances (TBARS; an index of lipid peroxidation) and decreases in the contents of hexosamine (a marker of gastric mucus) and adherent mucus, which occurred in gastric mucosal tissues after C48/80 treatment, were significantly attenuated by ginsenoside Re. The elevation of Bax expression and the decrease in Bcl2 expression after C48/80 treatment were also attenuated by ginsenoside Re. Ginsenoside Re significantly attenuated all these changes 3 h after C48/80 treatment. These results indicate that orally administered ginsenoside Re protects against C48/80-induced acute gastric mucosal lesions in rats, possibly through its stimulatory action on gastric mucus synthesis and secretion, its inhibitory action on neutrophil infiltration, and enhanced lipid peroxidation in the gastric mucosal tissue.