Eriko Kagi

Laboratory spectroscopy of MgNC : the first radioastronomical identification of Mg-bearing molecule

The linear MgNC radical was detected, for the first time, by laboratory microwave spectroscopy, and six unidentified lines in IRC +10216 reported by Guelin et al. (1986) were assigned to the transitions of this radical. The radical was produced in a free space absorption cell by a DC discharge in a mixture of magnesium vapor, argon, and cyanogen. Observed spectral lines in the 250-370 GHz region were analyzed by using the 2 Σ energy level expression, to give the rotational, centrifugal distortion and spin-rotation constants: B 0 = 5966.896(24) MHz, D 0 =0.004 2338(35) MHz, H 0 =0.308(16)×10 −7 MHz, and B 0 =15.219(13) MHz, with one standard deviation in parentheses

Laboratory Detection and Rotational Rest Frequencies of NaSH

The first laboratory spectrum of sodium hydrogensulfide, NaSH, is observed in the millimeter- and submillimeter-wavelength regions by direct absorption spectroscopy. The NaSH molecule is produced in a DC glow discharge plasma of a gaseous mixture of sodium, hydrogensulfide, and argon. A total of 100 a-type rotational transitions with Ka<10 in its ground state is measured in the frequency range 230-395 GHz. The spectrum of an isotopic species, NaSD, is also observed to confirm our identification of the species. The observed spectral lines are analyzed with a Hamiltonian for asymmetric top molecules, and the rotational, centrifugal distortion, and higher-order centrifugal distortion parameters for NaSH and NaSD are accurately determined. The r0 structure of NaSH is derived from the observed rotational constants of NaSH and NaSD: r0(Na—S) = 2.478(2) A, r0(S—H) = 1.396(7) A, bond angle Na—S—H = 92(1) degrees, with 1 s.d. values in parentheses. The observed molecular constants produce accurate transition frequencies for NaSH in the millimeter-wavelength region and thereby enable the searches for these lines in interstellar and circumstellar sources with radio telescopes.

Analysis of the 0g−(3P1)–B ′3 Π(0u−) system of I2 by perturbation-facilitated optical–optical double resonance

We present the analysis of the 0g−(3P1)–B ′3Π(0u−) system of I2. Both of the states are optically forbidden to access from the X 1Σg+ ground state, and the perturbation-facilitated optical–optical double resonance technique is used to access the 0g−(3P1) ion-pair state in the stepwise excitation. The intermediate states we used are the B 3Π(0u+)∼(3)0u− states coupled by hyperfine interaction, which are identified in the high vibrational levels of the B 3Π(0u+) state near the dissociation limit. These coupled states have the mixed character of the 0u+ and 0u− states, and allow to combine the X 1Σg+ ground state with the 0g−(3P1) state in the (1+1) photon excitation following the optical selection rules for one photon transition: 0g−(3P1)←(3)0u−∼B 3Π(0u+)←X 1Σg+. We elucidate the B 3Π(0u+)∼(3)0u− coupling scheme in the intermediate states by analyzing the second step of double resonance. The 0g−(3P1) state is located on the absolute energy axis and its molecular constants are reported. The B ′3Π(0u−) valenc...

Isotope 18O/16O ratio measurements of water vapor by use of the 950-nm wavelength region with cavity ring-down and photoacoustic spectroscopic techniques.

Two optical methods, cavity ring-down spectroscopy and photoacoustic spectroscopy, are applied to the measurement of the isotope ratio 18O/16O in water-vapor samples with a Nd3+:YAG pumped-dye laser. The combination band of (2v1 + v3) in the 960-nm region of water molecules is investigated for two standard water samples, the Vienna Standard Mean Ocean Water and the Standard Light Antarctic Precipitation. The results demonstrate that the two methods have the potential of compact systems for in-situ measurements of H2O isotope ratio in the environment.