Engineering topics
Publications and source records attributed to Yamamoto, Satoshi.
Abstract not provided
We have detected a new interstellar molecule, H2CN (methylene amidogen), in the cold, dark molecular cloud TMC-1. The column density of H2CN is estimated to be approximately 1.5 x 10(exp 11) cm(exp -2) by assuming an excitation temperature of 5 K. This column density corresponds to a fractional abundance relative to H2 of approximately 1.5 x 10(exp -11). This value is more than three orders of magnitude less than the abundance of the related molecule HCN in TMC-1. We also report a tentative detection of H2CN in Sgr B2(N). The formation mechanism of H2CN is discussed. Our detection of the N2CN molecule may suggest the existence of a new series of carbon-chain molecules, CH2C(n)N (N = 0, 1, 2, ...).
Attention is given to the carbon chain molecule H2CCCC, detected in the dark cloud TMC-1 for the first time in the course of a molecular line survey using the Nobeyama 45-m telescope. From nine transitions observed in the frequency region of 17-45 GHz, the total column density of H2CCCC in TMC-1 is derived to be 7.5(+/-2.0) x 10 exp 12/sq cm, which is about half of the value reported in IRC + 10216. Five transitions of a related carbon chain molecule, H2CCC, were also detected in TMC-1. The column density of H2CCC obtained in TMC-1, 2.8(+/-0.9) x 10 exp 12/sq cm, is a factor of three smaller than that of H2CCCC. The ortho-to-para abundance ratios of H2CCCC and H2CCC were found to be 4.2 +/-1.5 and 5.9 +/-2.0, respectively. The chemical reactions of these carbon-chain molecules in dark clouds are discussed.
An asymmetric-top free radical CH2CN with a 2B1 ground state was detected by laboratory microwave spectroscopy. The radical was produced in a free-space absorption cell by a DC glow discharge in pure CH3CN gas. About 60 fine-structure components were observed for the N = 11-10 to 14-13 a-type rotational transitions in the frequency region of 220-260 GHz. Hyperfine resolved components for the N = 4-3 and 5-4 transitions were resolved in the 80 and 100 GHz regions, respectively. Molecular constants were determined and U100602 and U80484 from Sgr B2, and U40240 and U20120 from TMC-1 were assigned to the N = 5-4, 4-3, 2-1, and 1-0 transitions with K(-1) = 0 of the CH2CN radical.