A reassessment of the Hypoglossum group (Delesseriaceae, Rhodophyta), with a critique of its genera

A reassessment of the Hypoglossum group (Delesseriaceae, Rhodophyta), with a critique of its genera. Eight genera are assigned to the Hypoglossum Kützing, Phitymophora J. Agardh, Pseudobranchioglossum Bodard, and Zellera Martens. The circumscription of the group is emended to include forms with network-forming ( Zellera ) an dspirally twisted ( Duckerella ) thalli. The definition of the group is lalso modified to include members (e.g. some species of Hypoglossum ) in which tetrasporangia are produced by primary cells as in the Caloglossa group. Exogenous branching, a distinguishing feature of the closely related Caloglossa group, never occurs in the Hypoglossum group.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47938/1/10152_2006_Article_BF02365624.pd

AN AB INITIO MOLECULAR ORBITAL STUDY OF LOW LYING ELECTRONIC EXCITED STATES OF FeC

$^{a}$K. Aiuchi, K. Tsuji and K. Shibuya Chem. Phys. Lett. 309, 229, (1999).Author Institution: Department of Chemistry, Faculty of Science, Ochanomizu University,; Department of Chemistry, Faculty of Science, National Institute for Advanced Interdisciplinary Research; Department of Chemistry, Graduate School of Science and Engineering, Tokyo Institute of TechnologySpectroscopic constants and energy levels of the ground and low-lying excited states of iron carbide, FeC, have been calculated from potential energy functions obtained by the ab initio MR-SDCI molecular orbital approach. Investigated states are $^{1}\Delta$ and $^{5}\Pi$, both of which are proposed by DF $spectra^{a}$ as a candidate for the new $\Omega = 2$ electronic state observed above the $^{3}\Delta_{2}$ state by $3460 cm^{-1}$. The character of each electronic state has been discussed theoretically. Contrary to the previous tentative assignment to $^{5}\Pi$, the MR-SDCI results predict that the observed $\Omega = 2$ state should be the $^{1}\Delta$ state and be located at $3252 cm^{-1}$ above $^{3}\Delta_{2}$. The spin-orbit coupling constant for $^{3}\Delta$ state has also been calculated

AN AB INITIO MOLECULAR ORBITAL STUDY ON THE STRUCTURE AND SPECTROSCOPIC PROPERTIES OF MAGNESIUM DICARBIDE

Author Institution: Department of Chemistry, Faculty of Science, Ochanomizu University; National Institute of Materials and Chemical Research, 1-1 Higashi; Hiroshima City University, 3-4-1 Ozukahigashi; Nobeyama Radio Obverservatory, MinamimakiA magnesium-bearing molecule $MgC_{2}$ is one of the candidate to be found in the envelope of a carbon star. Element magnesium may be rich in astrophysical objects because the elemental cosmic abundance of magnesium and silicon is almost the same, while silicon containing molecules such as $SiO, SiS, SiC, SiC_{2}, SiC_{4}, SiH_{4}, SiN$, have been found in interstellar space. Silicon dicarbide $SiC_{2}$ was discovered in IRC+10216. Now, magnesium dicarbide, $MgC_{2}$, is strongly expected to be observed. Since none of the experimental spectroscopic data on $MgC_{2}$ has been reported in any frequency region, ab initio molecular orbital predicition has been requested for its identification. The MR-SDCI+Q calculations with augmented cc-pVQZ basis sets have predicted that the ground state $MgC_{2} (^{1}A_{1})$ has T-shaped structure of $C_{2v}$ symmetry consisting of $Mg^{-}$ cation and $CC^{-}$ moiety with the dipole moment of 7.9 Debye. The CC and MgC distances have been found to be 1.275 and 2.012 \AA in its equilibrium geometry. The MR-SDCI+Q three-dimensional potential energy surface consisting of 497 points were analysed by the 2nd-order perturbation theory, predicting the rotational constants $A_{0}, B_{0}$, and $C_{0}$ to be $51794.0, 11493.9$ and 9378.7 MHz, and the centrifugal distortion constants $\Delta_{J}, \Delta_{JK}, \Delta_{K}, \delta_{J}, \delta_{K}$ to be $0.014, 0.21, -0.023, 0.0027, 0.14 MHz$, respectively. The $\nu_{1} (CC stretching), \nu_{2}(Mg-C_{2} streching)$, and $_{3}$(bending) vibrational frequencies have been estimated to be 1704.2, 594.8 and $455.8 cm^{-1}$, respectively. These results indicate that $MgC_{2}$ molecule is a rigid molecule unlike the analogue $SiC_{2}$, which is known as a molecule with large-amplitude motion. Toward the laser induced fluorescent spectroscopy, the vertical excitation energies for $\bar{A}^{1}A_{1}\leftarrow \tilde{X}{^{1}}A_{1}$ and $\bar{B}{^{1}}B_{2}$ transitions have also been calculated to be 8334 and $13034 cm^{-1}$, respectively, at the CAS-SCF level of theory