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2. Thermal radiative cooling of carbon cluster cations C$_N^+$, $N = 9, 11,12, 17-27$

Author

Iida, Shimpei, Hu, Wei, Zhang, Rui, Tanuma, Hajime, Masuhara, Kei, Ferrari, Piero, Shiromaru, Haruo, Azuma, Toshiyuki, and Hansen, Klavs

Subjects
Physics - Chemical Physics
Abstract

The radiative cooling rates of C$_N^+$ clusters ($N = 9, 11, 12, 17-27$) have been measured in the ultrahigh vacuum of an electrostatic storage ring to values on the order of $10^4$ s$^{-1}$. The rates were measured as a competing channel to unimolecular decay, and the rate constants pertain to the excitation energies where these two channels compete. Such high values can only be explained as photon emission from thermally excited electronic states, a mechanism that has also been seen in polycyclic aromatic hydrocarbon cations. The high rates have a very strong stabilizing effect on the clusters and the underlying mechanism gives a high energy conversion efficiency, with the potential to reach high quantum efficiencies in the emission process. The competing decay of unimolecular fragmentation defines upper limits for photon energies that can be down-converted to lower energy photons. Including previously measured cluster sizes provides the limits for all clusters C$_N^+$, $N=8-27$, of values that vary from 10 to 14.5 eV, with a general increase with size. Clusters absorbing photons of energies below these limits cool down efficiently by emission of photons via electronic transitions and their fragmentation is strongly reduced, increasing their survival in HI regions., Comment: 10 pages, 7 figures

Published
2021
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4. Properties of Kilonovae from Dynamical and Post-Merger Ejecta of Neutron Star Mergers

Author

Tanaka, Masaomi, Kato, Daiji, Gaigalas, Gediminas, Rynkun, Pavel, Radziute, Laima, Wanajo, Shinya, Sekiguchi, Yuichiro, Nakamura, Nobuyuki, Tanuma, Hajime, Murakami, Izumi, and Sakaue, Hiroyuki A.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Ejected material from neutron star mergers give rise to electromagnetic emission powered by radioactive decays of r-process nuclei, which is so called kilonova or macronova. While properties of the emission are largely affected by opacities in the ejected material, available atomic data for r-process elements are still limited. We perform atomic structure calculations for r-process elements: Se (Z=34), Ru (Z=44), Te (Z=52), Ba (Z=56), Nd (Z=60), and Er (Z=68). We confirm that the opacities from bound-bound transitions of open f-shell, Lanthanide elements (Nd and Er) are higher than those of the other elements over a wide wavelength range. The opacities of open s-shell (Ba), p-shell (Se and Te), and d-shell (Ru) elements are lower than those of open f-shell elements and their transitions are concentrated in the ultraviolet wavelengths. We show that the optical brightness can be different by >2 mag depending on the element abundances in the ejecta such that post-merger, Lanthanide-free ejecta produce brighter and bluer optical emission. Such blue emission from post-merger ejecta can be observed from the polar directions if the mass of the preceding dynamical ejecta in these regions is small. For the ejecta mass of 0.01 Msun, observed magnitudes of the blue emission will reach 21.0 mag (100 Mpc) and 22.5 mag (200 Mpc) in g and r bands within a few days after the merger, which are detectable with 1m or 2m-class telescopes., Comment: 11 pages, 9 figures, submitted to ApJ

Published
2017
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8. Charge Exchange Spectroscopy of Multiply Charged Erbium Ions

Author

Nishimura, Yuki, primary, Imaizumi, Saki, additional, Tanuma, Hajime, additional, Nakamura, Nobuyuki, additional, Sekiguchi, Yuichiro, additional, Wanajo, Shinya, additional, Sakaue, Hiroyuki A., additional, Kato, Daiji, additional, Murakami, Izumi, additional, Tanaka, Masaomi, additional, and Gaigalas, Gediminas, additional

Published
2023
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9. Model calculation for ion mobility in air using the MOBCAL program

Author

Takaya, Kazunari, Kaneko, Takahiro, Tanuma, Hajime, Nishide, Tatsuhiro, Sugiyama, Hiroaki, Nakano, Nobuo, Nagashima, Hisayuki, and Seto, Yasuo

Abstract

We determined new potential parameters for a calculation of ion mobility in air using the MOBCAL program. In our model, we regard air as a virtual uni-atomic molecular gas. And the Lennard-Jones parameters for various kinds of atoms in molecular ions were determined with simple and systematic methods. Using these parameters, we have calculated the mobilities of product ions from chemical warfare agents, normal saturated hydrocarbons, and illicit drugs. Most of the calculation results showed good agreement with the experimental values. Therefore this calculation method will be useful for understanding of the ion mobility spectrometry in air.

Published
2024
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10. Mobilities of polyatomic molecular ions in He gas

Author

Takaya, Kazunari, Hasegawa, Yuya, Koizumi, Tetsuo, and Tanuma, Hajime

Abstract

The mobilities of polyatomic molecular ions in He gas, measured at 83 and 306 K using a low-temperature drift tube, were smaller than the polarization limit Kpol. The mobilities of atomic or small molecular ions tended to show a bump at intermediate reduced field, and then approach the polarization limit at low reduced field; however, the measured mobilities of polyatomic molecular ions were different. We compared the experimental mobilities with values calculated using the MOBCAL program, and found that they agreed well.

Published
2024
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14. Laser Induced Breakdown Spectroscopy of Er II for Transition Probability Measurements

Author

NAOI, Yuki, IWATA, Masayuki, YOKOTA, Daichi, GAIGALAS, Gediminas, KATO, Daiji, MURAKAMI, Izumi, SAKAUE, Hiroyuki A., SEKIGUCHI, Yuichiro, TANAKA, Masaomi, TANUMA, Hajime, WANAJO, Shinya, NAKAMURA, Nobuyuki, NAOI, Yuki, IWATA, Masayuki, YOKOTA, Daichi, GAIGALAS, Gediminas, KATO, Daiji, MURAKAMI, Izumi, SAKAUE, Hiroyuki A., SEKIGUCHI, Yuichiro, TANAKA, Masaomi, TANUMA, Hajime, WANAJO, Shinya, and NAKAMURA, Nobuyuki

Abstract

We present a laser induced breakdown spectrum of Er II in the near ultraviolet region. To use the spectrum for the evaluation of the transition probabilities, an alloy target with a low content of Er was used to suppress the self-absorption. From the linearity of the Boltzmann plot obtained by using the sensitivity corrected experimental intensity and existing transition probability data, the local thermal equilibrium condition of the plasma and the reliability of the transition probability data are confirmed. The linear function obtained in the Boltzmann plot is used for the determination of a previously unreported transition probability for the line at 393.863 nm., source:Appl. Sci. 2022, 12(4), 2219; https://doi.org/10.3390/app12042219, source:https://doi.org/10.3390/app12042219

Published
2022

28. Modeling of radiative properties of Sn plasmas for extreme-ultraviolet source.

Author

Sasaki, Akira, Sunahara, Atsushi, Furukawa, Hiroyuki, Nishihara, Katsunobu, Fujioka, Shinsuke, Nishikawa, Takeshi, Koike, Fumihiro, Ohasni, Hayato, and Tanuma, Hajime

Subjects
ULTRAVIOLET radiation, MICROLITHOGRAPHY, IONS, WAVELENGTHS, ATOMIC structure
Abstract

Atomic processes in Sn plasmas are investigated for application to extreme-ultraviolet (EUV) light sources used in microlithography. We develop a full collisional radiative (CR) model of Sn plasmas based on calculated atomic data using Hebrew University Lawrence Livermore Atomic Code (HULLAC). Resonance and satellite lines from singly and multiply excited states of Sn ions, which contribute significantly to the EUV emission, are identified and included in the model through a systematic investigation of their effect on the emission spectra. The wavelengths of the 4d-4f+4p-4d transitions of Sn5+ to Sn13+ are investigated, because of their importance for determining the conversion efficiency of the EUV source, in conjunction with the effect of configuration interaction in the calculation of atomic structure. Calculated emission spectra are compared with those of charge exchange spectroscopy and of laser produced plasma EUV sources. The comparison is also carried out for the opacity of a radiatively heated Sn sample. A reasonable agreement is obtained between calculated and experimental EUV emission spectra observed under the typical condition of EUV sources with the ion density and ionization temperature of the plasma around 1018 cm-3 and 20 eV, respectively, by applying a wavelength correction to the resonance and satellite lines. Finally, the spectral emissivity and opacity of Sn plasmas are calculated as a function of electron temperature and ion density. The results are useful for radiation hydrodynamics simulations for the optimization of EUV sources. [ABSTRACT FROM AUTHOR]

Published
2010
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32. Ion mobility measurements for O+ and N+ in helium gas at 4.35 K.

Author

Sanderson, Joseph, Tanuma, Hajime, Kobayashi, Nobuo, and Kaneko, Yozaburo

Subjects
*HELIUM, *TEMPERATURE
Abstract

The mobilities of O+ and N+ in He have been measured using a liquid helium cooled, selected ion drift tube, at 4.35 K. Results are compared with previous experimental work at higher temperatures and, in the case of O+, comparison is made with theoretical work, where a good agreement is found. The dependence of mobility on effective temperature is discussed in light of our previous work and our measurements are related to features of the ion–atom potential. In order to facilitate further theoretical analysis, recommended values of mobility are tabulated for O+ and N+ in He and also for O+2, N+2, and CO+ in He. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
1995
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33. Shape resonance in heavy particle collisions

Author

Tanuma, Hajime, Matoba, Shiro, and Otsuki, Kazumasa

Subjects
イオン移動度, 原子衝突, shape resonance, 形状共鳴, 重粒子衝突, neutral particle, ポテンシャルエネルギー面, 中性粒子, ion mobility, オービティング共鳴, photoexcitation, orbiting resonance, 光励起, heavy particle collision, atomic collision, potential energy surface
Abstract

資料番号: AA0048091003

Published
2005

34. Advances in positron and electron scattering*

Author

Limão-Vieira, P., García, Gustavo, Krishnakumar, E., Petrovic, Z., Sullivan, James, Tanuma, Hajime, Limão-Vieira, P., García, Gustavo, Krishnakumar, E., Petrovic, Z., Sullivan, James, and Tanuma, Hajime

Abstract

The topical issue on Advances in Positron and Electron Scattering” combines contributionsfrom POSMOL 2015 together with others devoted to celebrate the unprecedented scientificcareers of our loyal colleagues and trusted friends Steve Buckman (Australian NationalUniversity, Australia) and Michael Allan (University of Fribourg, Switzerland) on theoccasion of their retirements. POSMOL 2015, the XVIII International Workshop on Low-EnergyPositron and Positronium Physics and the XIX International Symposium on Electron-MoleculeCollisions and Swarms, was held at Universidade NOVA de Lisboa, Lisboa, Portugal, from17–20 July 2015. The international workshop and symposium allowed to achieve a veryprivileged forum of sharing and developing our scientific expertise on current aspects ofpositron, positronium and antiproton interactions with electrons, atoms, molecules andsolid surfaces, and related topics, as well as electron interactions with molecules inboth gaseous and condensed phases. Particular topics include studies of electroninteractions with biomolecules, electron induced surface chemistry and the study of plasmaprocesses. Recent developments in the study of swarms are also fully addressed. EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2016

Published
2016

37. Possibility of Stark effect in charge transfer excitation of multiply charged ions

Author

Tanuma, Hajime, Konnai, Akiko, and Kobayashi, Nobuo

Subjects
電荷移行反応, Stark effect, optical polarization, Coulombポテンシャル, degeneration, 多価イオン, 偏光, 電場効果, イオン衝突, 縮退, ionic collision, ECR, research and development, multiply charged ion, Stark効果, C(4+), light emission, charge transfer excitation, electric field effect, Coulomb potential, 光放出, 研究開発
Abstract

資料番号: AA0045918017

Published
2003

43. Possibility of atom movement by very low energy electron beam irradiation

Author

Tanuma Hajime, Tomio Yaguchi, Isato Watanabe, Shigehiko Yamamoto, and Sasaki Susumu

Subjects
Steady state, Field (physics), business.industry, Chemistry, Potential method, Surfaces and Interfaces, Condensed Matter Physics, Cathode, Surfaces, Coatings and Films, law.invention, Optics, law, Monolayer, Atom, Materials Chemistry, Work function, Atomic physics, business, Common emitter
Abstract

The change in the work function of a (W-Sc2W3O12) coated impregnated cathode is observed during the course of work function measurements by means of the retarding potential method utilizing a titaniated W(100) field emitter electron source. The change in work function is negligibly small at the work function minimum but it increases as the final steady state work function value increases. This paper discusses how low energy electron beam irradiation on the order of 2–3 eV, which reduces the effective coverage of the surface monolayer on the cathode, increases the work function.

Published
1990

46. Formation of polarized excited states in charge-transfer reactions of multivalent ions

Author

Tanuma, Hajime, Konnai, Akiko, and Kobayashi, Nobuo

Subjects
偏極, molecular collision, 電子移動, polarization, 原子衝突, 電子構造, charge transfer, target molecule, electronic structure, electron transfer, angular momentum, 標的分子, 電子サイクロトロン共鳴, 電荷移動, electron cyclotron resonance, 分子衝突, 角運動量, atomic collision
Abstract

資料番号: AA0047272015

Published
2004

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