Akinori Murakami

Detection of a New Circumstellar Carbon-Chain Molecule, C4Si

A new interstellar carbon chain molecule, C4Si, has been detected in the envelope of the evolved star IRC + 10216. This molecule is the carrier of six unidentified lines which had been detected during the molecular line survey at Nobeyama Radio Observatory. The identification was made through astronomical detections followed by quantum chemical calculations and laboratory spectroscopic experiments. The rotational constant and the centrifugal distortion constant were B(0) = 1533.77206(146) MHz and D(0) = 0.00005827(35) MHz, respectively, where the numbers in parentheses represent one standard deviation in units of the last significant digits. The rotation temperature and the column density were 15 + or - 2 K and (7 + or - 1) x 10 to the 12th/sq cm, respectively, assuming a source size of 25 arcsec. 16 refs.

Laboratory and astronomical detection of the cyclic C3H radical

Laboratory and astronomical detections of the rotational spectrum of the cyclic C/sub 3/H radical are reported, and the formation process by ion-molecular reactions is discussed. Laboratory production of the radical involved the discharging of a mixture of C/sub 2/H/sub 2/, CO and He, following which 49 lines were assigned and the molecular constants determined. The astronomical search was conducted using the 2(12)-1(11) transition at 91.5 GHz whose four fine and hyperfine components have been detected toward TMC-1. A column density estimation of 6 x 10 to the 12th/sq cm has been obtained for the cyclic C/sub 3/H. 21 references.

Near-Infrared Absorbing Boron-dibenzopyrromethenes that Serve As Light-Harvesting Sensitizers for Polymeric Solar Cells

Hexylthiophene-conjugated boron-dibenzopyrromethenes with benzo[1,3,2]oxazaborinine rings, 1, that absorb near-infrared light with relatively high molecular extinction coefficients have been synthesized. The incorporation of 3-hexylthiophene-conjugated dye 1a at a blend ratio of 5 wt % into a polymeric solar cell based on a P3HT/indene-C(70) bisadduct (IC(70)BA) bulk heterojunction structure improved power conversion efficiency from 3.7 to 4.3%. The present work suggests that well-defined near-infrared absorbing BODIPY analogues can potentially be used as photosensitizers in polymeric solar cells.

A quantum chemical study on the linear C2S and C3S molecules

The molecular structure of the linear C2S and C3S molecules were studied by a quantum chemical method. The calculated rotational constant is 6438 MHz for C2S and 2888 MHz for C3S. After vibrational correction, these values agree closely with experiment. The calculated dipole moments of C2S and C3S are 2.8 D and 3.6 D, respectively. The addition of a carbon atom stabilizes the short carbon-chain monosulfides about 100-160 kcal/mol. 18 refs.

On the electron affinities of hexafluorides CrF6, MoF6, and WF6

The adiabatic electron affinities (EAs) of MF6 and MF−6 (M=Cr, Mo, and W) are calculated in a configuration interaction (CI) calculation using a model potential method. The calculated EA of 3.85 eV for WF6 agrees well with the observed values. The difference (1.52 eV) between the calculated EA of MoF6 and that of WF6 shows also a very good agreement with the experimental ones. CrF6 has a very high EA of 8.24 eV. The CrF−6 anion has positive EA and the CrF2−6 dianion is thus most stable in the CrFq−6 (q=0, 1, and 2) sequence, while WF−6 does not have a positive EA. The EAs of MF6 calculated by CI calculations are smaller than those by SCF calculations. This negative correlation effect on the AEs is also discussed.

Laboratory detection of C5S by pulsed-discharge-nozzle Fourier transform microwave spectroscopy

The rotational spectrum of C 5 S in the X 1 Σ + (υ=0) ground state has been observed for the first time using a Fabry-Perot-type Fourier transform microwave spectrometer combined with a pulsed discharge nozzle. C 5 S was generated by a discharge in a mixture of CS 2 and C 2 H 2 diluted in Ar, and subsequently cooled down to a few kelvins in a supersonic jet. Eight rotational transitions of C 5 32 S have been observed in the 5-20 GHz region. Three lines for the less abundant 34 S species have also been detected to confirm the carrier of the observed lines to be C 5 S

Theoretical study of the recently observed 3Πg state of the F2 molecule

An ab initio theoretical investigation is carried out mainly on the 3 Pi g state of the fluorine molecule (F2). Results support the assignment of the new triplet state observed by Hoshiba and co-workers (1985) as 3 Pi g. A possibility concerning the laser transition of the 3 Pi u from 3 Pi g system is discussed.

Comparison of the equilibrium geometry of acetylene (C2H2) and disilyne (Si2H2)

Abstract The equilibrium geometry of disilyne is not linear, but is twisted. The potential surfaces of acetylene and disilyne have a critical internuclear distance between the central atoms, where the stable geometry changes from linear to twisted forms the R-dependence of the valence-shell electron energy causes the difference in the structure of the molecules.

The structures of the cyclic-C3H radical — an interstellar molecule

Abstract The equilibrium structure of the cyclic C 3 H radical was obtained by ab initio computation. The total energy at a C s optimum structure is lower than that of a C 2v optimum structure by only 10 −4 hartree and the adiabatic potential surface for the antisymmetric motion is so flat that no locally bound vibrational level exists around the C s minimum; the force constant for the CC antisymmetric stretching mode is about one sixth of that for the CC symmetric stretching mode.