研究者詳細 - 宮本　祐樹

Refractive index measurements of solid parahydrogen 査読

Perera, M., Tom, B.A., Miyamoto, Y., Porambo, M.W., Moore, L.E., Evans, W.R., Momose, T., McCall, B.J.

Optics Letters 36 ( 6 ) 840 - 842 2011年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：OPTICAL SOC AMER

Solid para-H-2 is a promising gain medium for stimulated Raman scattering, due to its high number density and narrow Raman linewidth. In preparation for the design of a cw solid hydrogen Raman laser, we have made the first measurements, to our knowledge, of the index of refraction of a solid para-H-2 crystal, in the wavelength range of 430-1100 nm. For a crystal stabilized at 4.4 K, this refractive index is measured to be n(p-H2) 1.130 +/- 0.001 at 514 nm. A slight, but significant, dependence on the final crystal-growth temperature is observed, with higher n(p-H2) at higher crystal-growth temperatures. Once a crystal is grown, it can be heated up to 10 K with no change in n(p-H2). The refractive index varies only slightly over the observed wavelength range, and no significant birefringence was observed. (C) 2011 Optical Society of America

DOI： 10.1364/OL.36.000840

Spectroscopy of HF and HF-containing clusters in solid parahydrogen 査読

Miyamoto, Y., Ooe, H., Kuma, S., Kawaguchi, K., Nakajima, K., Nakano, I., Sasao, N., Tang, J., Taniguchi, T., Yoshimura, M.

Journal of Physical Chemistry A 115 ( 50 ) 14254 - 14261 2011年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

We report measurements of FT-IR absorption spectroscopy of HF, DF, and their clusters in solid parahydrogen (pH(2)). The observed spectra contain many absorption lines which were assigned to HF monomers, HF polymers, and clusters with other species, such as N-2, O-2, orthohydrogen (oH(2)), etc. The rotational constants of HF and DF monomers were determined from the cooperative transitions of the vibration of solid pH(2) and the rotation of HF and DF. Small reduction of the rotational constants indicates that HF and DF are nearly free rotors in solid pH(2). Time dependence of the spectra suggests that HF and DF monomers migrate in solid pH(2) and form larger polymers, probably via tunneling reactions through high energy barriers on inserting another monomer to the polymers. The line width of HF monomers in solid pH(2) was found to be 4 cm(-1), which is larger than that of other hydrogen halides in solid pH(2). This broad line width is explained by rapid rotational relaxation due to the accidental coincidence between the rotational energy of HF and the phonon energy with maximum density of states of solid pH(2) and the rotational translational coupling in a trapping site.

DOI： 10.1021/jp207419m

Airborne Flight Campaign for GOSAT Validation 査読

Tomoaki Tanaka, Daisuke Sakaizawa, Isamu Morino, Yuki Miyamoto, Makoto Inoue, Toshinobu Machida, Yousuke Sawa, Hidekazu Matsueda, Shuji Kawakami, Masakatsu Nakajima, Osamu Uchino

SENSORS, SYSTEMS, AND NEXT-GENERATION SATELLITES XV 8176 2011年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：SPIE-INT SOC OPTICAL ENGINEERING

Continuous validation of data observed by satellites, such as Greenhouse gases Observing SATellite (GOSAT), is important to qualify the long-term trends of greenhouse gases. High-precision data over the restricted region measured by ground-based high-resolution Fourier transform spectrometers (g-b FTS), airborne in-situ instruments, and flask sampling devices have been used for the validation of satellite data. As part of CAL/VAL (Calibration/Validation) activities of the GOSAT, airborne flight campaigns were performed over Tsukuba and Moshiri using the ground-based FTS, airborne in-situ and flask devices, and 1.57-mu m Laser Absorption Sensor (LAS). Airborne flask sampling and insitu carbon dioxide (CO2) sensors were carried out to obtain vertical profiles of the CO2 mixing ratio while ground-based FTS and LAS measured solar direct spectra and weighted column-averaged CO2, respectively. Those results were used to decide a calibration factor of the ground-based FTS and compared with GOSAT products over Tsukuba. We will report the comparison results of the aircraft campaign measurements and the retrieval value from the FTS.

DOI： 10.1117/12.898549

その他リンク： http://orcid.org/0000-0002-0567-6881

Producing and quantifying enriched para- H2 査読

Tom, B.A., Bhasker, S., Miyamoto, Y., Momose, T., McCall, B.J.

Review of Scientific Instruments 80 ( 1 ) 2009年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER INST PHYSICS

The production of enriched para-H-2 is useful for many scientific applications, but the technology for producing and measuring para-H-2 is not yet widespread. In this note and in the accompanying auxiliary material, we describe the design, construction, and use of a versatile standalone converter that is capable of producing para-H-2 enrichments of up to >= 99.99% at continuous flow rates of up to 0.4 SLM. We also discuss para-H-2 storage and back conversion rates, and improvements to three techniques (thermal conductance, NMR, and solid hydrogen impurity spectroscopy) used to quantify the para-H-2 enrichment.

DOI： 10.1063/1.3072881

Nuclear spin conversion of methane in solid parahydrogen 査読

Miyamoto, Y., Fushitani, M., Ando, D., Momose, T.

Journal of Chemical Physics 128 ( 11 ) 2008年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER INST PHYSICS

The nuclear spin conversion of CH(4) and CD(4) isolated in solid parahydrogen was investigated by high resolution Fourier transform infrared spectroscopy. From the analysis of the temporal changes of rovibrational absorption spectra, the nuclear spin conversion rates associated with the rotational relaxation from the J=1 state to the J=0 state for both species were determined at temperatures between 1 and 6 K. The conversion rate of CD(4) was found to be 2-100 times faster than that of CH(4) in this temperature range. The faster conversion in CD(4) is attributed to the quadrupole interaction of D atoms in CD(4), while the conversion in CH(4) takes place mainly through the nuclear spin-nuclear spin interaction. The conversion rates depend on crystal temperature strongly above 3.5 K for CH(4) and above 2 K for CD(4), while the rates were almost constant below these temperatures. The temperature dependence indicates that the one-phonon process is dominant at low temperatures, while two-phonon processes become important at higher temperatures as a cause of the nuclear spin conversion. (c) 2008 American Institute of Physics.

DOI： 10.1063/1.2889002

In situ photolysis of CD<inf>3</inf>i in solid orthodeuterium 査読

Fushitani, M., Miyamoto, Y., Hoshina, H., Momose, T.

Journal of Physical Chemistry A 111 ( 49 ) 12629 - 12634 2007年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

Photochemical reactions of molecules in solid orthodeuterium (o-D-2) have been studied by high-resolution infrared spectroscopy and compared with previous results obtained in solid parahydrogen (p-H-2). Ultraviolet photoplysis of CD3I molecules in solid o-D2 yielded CD3 radicals and iodine atoms efficiently, which indicates a small cage effect in solid o-D2, as in the case of solid p-H2. The Fourier transform infrared spectrum of the nu(3) vibrational band of CD3 showed a rotational structure with additional splitting due to crystal field interactions. The magnetic dipole transition (2P(1/2) (<-) P-2(3/2)) of the I atom isolated in solid o-D-2 was observed together with a strong rotational satellite of deuterium molecules through the electron-roton coupling in solid hydrogen. The tunneling reaction between CD3 and D-2 was not observed in a time scale of a few days, which gives the upper limit of the tunneling,reaction rate of 10(-8) s(-1) at 4.2 K.

DOI： 10.1021/jp0761113

Correlation between nuclear spin ratio of cyclic C3H2 and chemical evolution in TMC-1 cores 査読

Morisawa, Y., Fushitani, M., Kato, Y., Hoshina, H., Slmizu, Z., Watanabe, S., Miyamoto, Y., Kasai, Y., Kawaguchi, K., Momose, T.

Astrophysical Journal 642 ( 2 I ) 954 - 965 2006年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IOP PUBLISHING LTD

The ortho-to-para nuclear spin ratio of cyclopropenylidene ( cyclic C3H2) in TMC-1 cores was investigated using the 45 m radio telescope at Nobeyama Radio Observatory. We have observed four ortho lines (J(KaKc) = 2(12) - 1(01), 3(12) - 3(03), 3(21) - 3(12), and 3(30) - 3(21)) and four para lines (J(KaKc) 2(02) - 1(11), 2(11) - 2(02), 2(20) - 2(11), and 3(22) - 3(13)) of cyclic C3H2 in six cores in TMC-1. A statistical equilibrium analysis of the observed intensities revealed apparent correlation between the ortho-to-para ratio of cyclic C3H2 and chemical evolution of the molecular cloud; the ortho-to-para ratio in younger cores is less than 2, while that in older cores is close to the statistical ratio of 3. A simple chemical model calculation indicates that the correlation is ascribed to the conservation of nuclear spin angular momenta in chemical reactions relevant to the production, destruction, and reproduction of cyclic C3H2. Since cyclic C3H2 has been observed in a variety of sources, the ortho-to-para ratio of cyclic C3H2 may be a useful probe of chemical evolution of molecular clouds.

DOI： 10.1086/501041

Search for CCH^-, NCO^-, and NCS^- negative ions in molecular clouds 査読

Morisawa, Y., Hoshina, H., Kato, Y., Simizu, Z., Kuma, S., Sogoshi, N., Fushitani, M., Watanabe, S., Miyamoto, Y., Momose, T., Kasai, Y., Kawaguchi, K.

Publications of the Astronomical Society of Japan 57 ( 2 ) 325 - 334 2005年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：OXFORD UNIV PRESS

Despite several suggestions concerning the existence of negatively charged molecules and negative atomic ions in molecular clouds, few attempts have been made to search for negative ions in molecular clouds. In the present study, we extensively searched for three negative molecular ions (CCH-, NCO-, and NCS-) in a dark cloud, L134N, using the Nobeyama 45-m radio telescope. The three negative ions are molecules whose rotational constants have been reported based on laboratory experiments. After a long accumulation, a trace amount of an unidentified emission line was detected at a frequency close to the theoretical prediction of the J = 1-0 transition of CCH-. If this unidentified line is attributable to CCH-, the observed emission intensity would provide an estimation of the column density of CCH- in L134N to be 1.0 x 10(11) cm(-2), which corresponds to a fractional abundance of 5 x 10(-12) relative to hydrogen. However, our recent observation using the IRAM 30-m telescope did not reproduce the J = 1-0 signal, nor detect any trace of the J = 2-1 transition. Thus, the identification of CCH- in L134N is not yet confirmed. As for other ions, signals of neither NCO- nor NCS- were detected in L134N. Although we also searched for the three negative ions in a translucent cloud, CB228, and a star-forming region, SgrB2, no signals were detected. The upper limit abundances of the ions in these clouds are discussed limit abundances of the ions in these clouds are discussed.

DOI： 10.1093/pasj/57.2.325

Stimulated stokes downconversion in liquid and solid parahydrogen 査読

McCall, B.J., Huneycutt, A.J., Saykally, R.J., Lindsay, C.M., Oka, T., Fushitani, M., Miyamoto, Y., Momose, T.

Applied Physics Letters 82 ( 9 ) 1350 - 1352 2003年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER INST PHYSICS

We report the results of our preliminary investigations into the suitability of condensed-phase parahydrogen as a Raman-shifting medium for infrared cavity ringdown laser absorption spectroscopy. We have observed the conversion of similar to10-ns pulses of 532-nm radiation into first-, second-, and third-order vibrational Stokes radiation in bulk liquid and solid parahydrogen after a single 11-cm pass. Unexpectedly, we find that liquid H-2 yields more efficient conversion than solid H-2 with certain focal geometries, and that in the case of the solid, a collimated or loosely focused pump geometry is more efficient than a tight focus. (C) 2003 American Institute of Physics.

DOI： 10.1063/1.1556560

Generation of infrared radiation by stimulated Raman scattering in para-hydrogen crystal at 5 K 査読

Fushitani, M., Kuma, S., Miyamoto, Y., Katsuki, H., Wakabayashi, T., Momose, T., Vilesov, A.F.

Optics Letters 28 ( 1 ) 37 - 39 2003年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：OPTICAL SOC AMER

We report the preliminary results of our experiments with stimulated Raman scattering in para-hydrogen crystal aimed at developing a continuously tunable laboratory laser source of mid-infrared radiation. With laser pulses at 532 nm, a conversion efficiency for the first Stokes beam of as much as 20% in the forward direction was observed through a single-pass, 5-cm-long crystal. Generation of mid-infrared pulses at 4.5 mum was achieved by use of the output of a near-infrared pulsed laser (1.6 mum, 3 ns), and an absorption spectrum of gaseous CD4 molecules was successfully recorded. These results suggest use of the solid para-hydrogen Raman shifter as a promising light source for mid-infrared spectroscopy. (C) 2003 Optical Society of America.

DOI： 10.1364/OL.28.000037