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The methylene radical (C[H.sub.2]) was very important to Gerhard Herzberg. We have carried out high-resolution spectroscopic measurements on two energetically low-lying, pure rotational transitions of methylene in its ground vibrational--electronic state at frequencies near 2 THz. One of the transitions--the [N.sub.KaKc] = [2.sub.11] [left arrow] [2.sub.02] multiplet--belongs to ortho-C[H.sub.2] and is centered at 1.954 THz. The other rotational transition--the [N.sub.KaKc] = [l.sub.10] [left arrow] [l.sub.01] multiplet--belongs to para-C[H.sub.2] and is centered at 1.915 THz. Since the ground electronic state of methylene has [sup.3][B.sub.1] symmetry, the rotational transitions are split into three fine-structure components, while the ortho transitions are split additionally by hyperfine structure. In total, we have measured 29 new lines, six for the para transition and the remainder for the ortho transition. The newly measured lines can be added to high-resolution spectral data obtained by ourselves and others at lower frequencies. Progress towards a global fit is discussed. Key words: spectroscopy, THz frequencies, radicals, methylene, interstellar medium.

Although ammonia is an abundant molecule commonly observed towards the dense interstellar medium, it has not yet been established whether its main formation route is from gas-phase ion–molecule reactions or grain-surface hydrogen additions on adsorbed nitrogen atoms. Deuterium fractionation can be used as a tool to constrain formation mechanisms. High abundances of deuterated molecules are routinely observed in the dense interstellar medium, with the ratio between deuterated molecules and the main isotopologue enhanced by several orders of magnitude with respect to the elemental D/H ratio. In the case of ammonia, the detection of its triply deuterated isotopologue hints at high abundances of the deuterated intermediate nitrogen radicals, ND, NHD, and ND2. So far however, only ND has been detected in the interstellar medium. In this paper, to constrain the formation of ammonia, we aim at determining the NHD/NH2 and ND2/NHD abundance ratios, and compare them with the predictions of both pure gas-phase and grain-surface chemical models. We searched for the fundamental rotational transitions of NHD and ND2 towards the class 0 protostar IRAS16293−2422, towards which NH, NH2 and ND had been previously detected. Both NHD and ND2 are detected in absorption towards the source. The relative abundance ratios NH2:NHD:ND2 are close to 8:4:1. These ratios can be reproduced by our gas-phase chemical model within a factor of 2–3. Statistical ratios as expected from grain-surface chemistry are also consistent with our data. Further investigations of the ortho-to-para ratio in ND2 , both theoretical and observational, could bring new constraints to better understand nitrogen hydride chemistry. [ABSTRACT FROM AUTHOR]

Pure rotational spectra of the bromomethyl radical, CH2Br, were measured by using a Fourier transform microwave (FT-MW) spectrometer in order to fully resolve hyperfine structures arising from both the bromine and hydrogen nuclei. We detected a total of 124 lines for the 79Br and 81Br isotopomers, including Ka=0 (ortho species) and Ka=1 (para species). No hyperfine splitting due to the hydrogen nuclei was observed for the para species, directly confirming the planarity of the radical. We conducted a global analysis of our present FT-MW results and previous measurements in the millimeter-wave region and obtained an exhaustive list of molecular constants. The sign of the Fermi constant of the bromine nucleus was unambiguously determined to be positive, which is opposite to that found in previous work in the millimeter-wave region and in electron spin resonance experiment on this radical. The present study permitted a systematic comparison to be made of the hyperfine coupling constants of both the halogen and hydrogen nuclei for CH2X-type compounds, where X=F, Cl, and Br. [ABSTRACT FROM AUTHOR]

The pure rotational spectrum of the isocyanomethyl radical, CH2NC, was measured for the first time by using a Fourier transform microwave spectrometer. The molecule was produced by a discharge of isocyanomethane, CH3NC, diluted in Ar or Ne. The spectral lines due to the N=1-0 and 2-1 transitions were recorded near 22 and 44 GHz, respectively. The observed spectrum showed a complicated fine and hyperfine structure because of the same order of interaction energies. Among the 39 spectral lines detected and assigned, the transitions with Ka=1 show no hyperfine splitting due to the hydrogen nuclei, suggesting planarity for the molecule. Molecular constants such as rotational and spin-rotational parameters including centrifugal effects and hyperfine coupling constants due to both the nitrogen and the hydrogen nuclei were accurately determined. The structure and the astronomical implications of the molecule are discussed. [ABSTRACT FROM AUTHOR]

The hyperfine resolved rotational spectrum of the CH[sub 2]CP radical in the &Xtilde;²B[sub 1] ground electronic state has been observed for the first time using a Fourier transform microwave spectrometer in combination with a pulsed discharge nozzle. The radical was produced by discharging a mixture of PH[sub 3] and C[sub 2]H[sub 2] diluted in either Ar or Ne. A total of 25 hyperfine components of the 2[sub 02]-1[sub 01] and 3[sub 03]-2[sub 02] transitions have been measured which enabled us to precisely determine hyperfine coupling constants for both phosphorus and hydrogen nuclei. Spin densities on the phosphorus and β-carbon atoms, estimated from the hyperfine coupling constants, suggest that the radical forms an allenic structure (CP double bond) that is modified by a phosphoryl structure (CP triple bond), which is consistent with the theoretical estimation obtained previously by an ab initio calculation. The nature of the CP chemical bond in the radical is investigated in comparison with the corresponding nitrogen bearing counterparts. [ABSTRACT FROM AUTHOR]

High resolution two-color threshold photoelectron spectra of tropolone and 9-hydroxyphenalenone (9-HPO) isolated in a free jet expansion have been measured to study the proton tunneling phenomena in the cation ground state (D0). The tunneling splitting widths of the D0 zeroth vibrational level for the both molecules lie within our experimental accuracy (2 cm-1), indicating that the proton tunneling is inhibited when compared to that obtained in their respective neutral states. By means of a comparative study of these two molecules, the tunneling inhibition has been explained in terms of a large contribution from the electronic factor which represents the changes in charge distribution of the π electrons upon ionization. The geometric factor, which is associated with the ring planarity is less important in determining the rate of tunneling in the D0 state. In the case of tropolone, we have found that the measurement of an out-of-plane skeletal vibration in various electronic states make it possible to describe the tunneling path at a higher level than a simple one-dimensional description. Moreover, the adiabatic ionization energies of 9-HPO and the deuterated 9-HPO have been determined accurately to be 65 338±5 cm-1 (8.1009±0.0006 eV) and 65 350±5 cm-1 (8.1024±0.0006 eV), respectively. [ABSTRACT FROM AUTHOR]

In this work, the molecules styrene (ST) and phenylacetylene (PA), as well as their argon complexes ST–Ar and PA–Ar, have been investigated with (1+1’) resonance enhanced multiphoton ionization (REMPI) threshold photoelectron spectroscopy (TES). The first adiabatic ionization energies of ST, PA, ST–Ar, and PA–Ar have been measured as 68 267±5, 71 175±5, 68 151±5, and 71 027±5 cm-1, respectively. For both ST–Ar and PA–Ar, the first photoelectron band shows structure in the lowest frequency van der Waals (vdW) bending mode in the ground ionic state, with νvdW being measured as 15 cm-1 in each case. For each molecule excitation to a particular vibrational level of the S1 state followed by ionization, allows structure in that mode to be observed in the threshold photoelectron spectrum. This has been achieved for three modes in both styrene and phenylacetylene. The experimental ionic vibrational frequencies thus obtained, have been compared with those known for the S0 and S1 states. [ABSTRACT FROM AUTHOR]

Measurements of mass-selected ion-current and threshold photoelectron spectra of jet-cooled aniline–Arn van der Waals complexes (n=1 and 2) have been carried out with a two-color resonantly enhanced multiphoton ionization (REMPI) technique using a high-resolution threshold photoelectron analyzer developed in this laboratory. From our (1+1’) REMPI experiments via the respective excited S1 states, we have obtained photoelectron spectra with well-resolved vibrational progressions due to ‘‘low-frequency van der Waals modes’’ of the cations; νvdW=16 cm-1 (n=1) and νvdW=11 cm-1 (n=2). From Franck–Condon calculations, we have assigned these low-frequency vibrations to the ‘‘van der Waals bending’’ of the cations. We have also found that the angles of the van der Waals bonds in the cations are changed by 8.2 (n=1) and 8.8 (n=2) degrees with respect to the S1 states. The adiabatic ionization potentials (Ia) of aniline and the aniline–Arn complexes (n=1 and 2) have been determined as 62 268±4 cm-1 (aniline), 62 157±4 cm-1 (n=1), and 62 049±4 cm-1 (n=2). Their shifts ΔIa are 111 cm-1 (n=1) and 219 cm-1 (n=2) with respect to aniline. Spectral shifts due to complex formation have been observed for a total of 13 ring modes of the cations. [ABSTRACT FROM AUTHOR]

From our high resolution REMPI threshold photoelectron measurements of jet-cooled tropolone, it has been found that no spectral doublet showing ‘‘proton tunneling’’ in the cation ground state (D0) is observed within an experimental accuracy of 2 cm-1. The adiabatic ionization potential was obtained as Ia=68 365±5 cm-1. [ABSTRACT FROM AUTHOR]

The Japan Atomic Energy Agency is responsible for the procurement of the central solenoid (CS) conductor for ITER. The CS conductor uses a circular-in-square type sheath tube (jacket, outer dimension: 49 mm \times 49 mm square, inner diameter: 32.6 mm) made of high manganese stainless steel JK2LB. The CS jacket suffers high electromagnetic force with 60,000 cycles during its lifetime. Prior to mass-production of CS jacket sections for the ITER machine, production of 170 units of jacket sections has been carried out. During production, it was confirmed that dimensional and mechanical performances satisfy the ITER requirements. The nondestructive examination procedure for the CS jacket sections has been developed. As a result, mass-production processes of CS jacket have been established. [ABSTRACT FROM PUBLISHER]

The optimization of the heat treatment of \Nb3\Sn conductors for toroidal field coils in ITER was attempted to improve the current sharing temperatures (Tcs). Using the strand, we chose the pattern at 570  ^\circ\C for 250 h and 650  ^\circ\C for 100 h as the best, which increased the critical current and maintained the residual resistivity ratio higher than 100. The behavior of the critical current of the strand vs. the magnetic field, temperature, and strain was also improved. This pattern was used on two conductors, and their performances were tested. Tcs was evaluated over 1000 electromagnetic cycles and one thermal cycle. A sharp Tcs degradation occurred at 50 cycles. Then Tcs decreased linearly. Although this tendency was similar to the conductors that were heat treated with the original pattern, the degradation rates were improved. The ac losses (Q) before cycling were approximately 10% lower than those of the original pattern. Q after cycling became almost equivalent between two patterns. The conductor was inspected after the test, which showed that the conductor under the high-magnetic-field zone had contracted by approximately 600 ppm during the test. Some clearly deformed strands were observed under the high-magnetic-field zone, which could degrade Tcs. [ABSTRACT FROM PUBLISHER]

The performance of four \Nb3\Sn conductors for the ITER central solenoids was tested. The current sharing temperatures (Tcs) were measured over approximately 9000 electromagnetic cycles, including two or three thermal cycles between 4.2 K and room temperature. Tcs increased and became almost constant through the cycling. The gradient of the electric field against the temperature gradually decreased against cycling. The degradations caused by the electromagnetic force of the short twist pitch conductors were smaller than that of the original twist pitch conductor. The ac losses of short twist pitch conductors were several times higher than that of original twist pitch conductor. The dents and the removals of the Cr plating on the strands, which were formed during cabling, decreased the electric resistance between strands, which may cause the observed high ac loss. Inspection of the cable showed neither a clear bias of cable in the cross-sectional surface nor distorted strands in the lateral face. The high rigidity of the short twist pitch cable could prevent these plastic deformations, caused by the Lorentz force. [ABSTRACT FROM PUBLISHER]

We observed the diurnal variation of ozone (O3) in the vertical region between 250 and 0.0005 hPa (∼12-96 km) using the Superconducting Submillimeter-Wave Limb- Emission Sounder (SMILES) on the Japanese Experiment Module (JEM) of the International Space Station (ISS) between 12 October 2009 and 21 April 2010. The new 4K superconducting heterodyne receiver technology of SMILES allowed us to obtain a one order of magnitude better signal-to-noise ratio for the O3 line observation compared to past spaceborne microwave instruments. We assessed the quality of the vertical profiles of O3 in the 100-0.001 hP (∼16-90 km) region for the SMILES NICT Level 2 product version 2.1.5. The evaluation is based on four components; error analysis; internal comparisons of observations targeting three different instrumental setups for the same O3 625.371 GHz transition; internal comparisons of two different retrieval algorithms; and external comparisons for various local times with ozonesonde, satellite and balloon observations (ENVISAT/MIPAS, SCISAT/ACE-FTS, Odin/OSIRIS, Odin/SMR, Aura/MLS, TELIS). SMILES O3 data have an estimated absolute accuracy of better than 0.3 ppmv (3 %) with a vertical resolution of 3-4km over the 60 to 8 hPa range. The random error for a single measurement is better than the estimated systematic error, being less than 1, 2, and 7 %, in the 40-1, 80-0.1, and 100-0.004 hPa pressure region, respectively. SMILES O3 abundance was 10-20% lower than all other satellitemeasurements at 8-0.1 hPa due to an error arising from uncertainties of the tangent point information and the calibration problem for the intensity of the spectrum. The non sun-synchronous orbit of the ISS allowed us to observe O3 at various local times. A two month period is required to accumulate measurements covering 24 h in local time. However such a dataset can also contain variation due to dynamical, seasonal, and latitudinal effects. [ABSTRACT FROM AUTHOR]

Abstract: Guided by a previous microwave study (9–35GHz), the rotational spectrum of both chlorine isotopologues of chloroiodomethane in its vibrational and electronic ground state has been re-investigated in the microwave region and extended to the millimeter/submillimeter-wave region. Weak a-type transitions have been recorded by Fourier transform microwave spectroscopy below 20GHz whilst strong b-type rotational transitions have been recorded between 15 and 646GHz, corresponding to energy levels with J″≤108 and . Molecular constants including those describing the hyperfine structures owing to the two halogen atoms were accurately determined for both species from the least-squares analysis of a total of 1475 distinct transition frequencies (of which 906 belong to the CH2I35Cl isotopologue). The two sets of rotational constants allowed us to derive an r 0 structure of CH2ICl. [Copyright &y& Elsevier]

The vertebrate inner ear is derived from the otic placode and undergoes a complicated series of morphogenetic processes to differentiate into an elaborate structure harboring mechanosensory epithelia featuring hair cells, the mechanoreceptors of hearing and balance. Recently, the principal mechanisms producing hair cells and the key molecules involved in their fate determination and differentiation have been gradually unveiled. The in-depth understanding of hair cell development is consequently providing clues to strategies for mammalian hair cell regeneration. Among them, the identification and characterization of progenitor cells for the hair cell lineage, which is just emerging, is of particular interest. Herein, we review the molecular mechanisms of inner ear development with particular focus on perspectives for hair cell regeneration. [ABSTRACT FROM AUTHOR]

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Although ammonia is an abundant molecule commonly observed towards the dense interstellar medium, it has not yet been established whether its main formation route is from gas-phase ion–molecule reactions or grain-surface hydrogen additions on adsorbed nitrogen atoms. Deuterium fractionation can be used as a tool to constrain formation mechanisms. High abundances of deuterated molecules are routinely observed in the dense interstellar medium, with the ratio between deuterated molecules and the main isotopologue enhanced by several orders of magnitude with respect to the elemental D/H ratio. In the case of ammonia, the detection of its triply deuterated isotopologue hints at high abundances of the deuterated intermediate nitrogen radicals, ND, NHD, and ND2. So far however, only ND has been detected in the interstellar medium. In this paper, to constrain the formation of ammonia, we aim at determining the NHD/NH2 and ND2/NHD abundance ratios, and compare them with the predictions of both pure gas-phase and grain-surface chemical models. We searched for the fundamental rotational transitions of NHD and ND2 towards the class 0 protostar IRAS16293−2422, towards which NH, NH2 and ND had been previously detected. Both NHD and ND2 are detected in absorption towards the source. The relative abundance ratios NH2:NHD:ND2 are close to 8:4:1. These ratios can be reproduced by our gas-phase chemical model within a factor of 2–3. Statistical ratios as expected from grain-surface chemistry are also consistent with our data. Further investigations of the ortho-to-para ratio in ND2 , both theoretical and observational, could bring new constraints to better understand nitrogen hydride chemistry. [ABSTRACT FROM AUTHOR]