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Md produced in the 
He + 
Es reactionNishio, Katsuhisa; Hirose, Kentaro; Makii, Hiroyuki; Orlandi, R.; Kean, K. R.*; Tsukada, Kazuaki; Toyoshima, Atsushi*; Asai, Masato; Sato, Tetsuya; Chiera, N. M.*; et al.
Physical Review C, 111(4), p.044609_1 - 044609_12, 2025/04
Times Cited Count：1 Percentile：59.26(Physics, Nuclear)
Chiera, N. M.*; Sato, Tetsuya; Eichler, R.*; Tomitsuka, Tomohiro; Asai, Masato; Adachi, Sadia*; Dressler, R.*; Hirose, Kentaro; Inoue, Hiroki*; Ito, Yuta; et al.
Angewandte Chemie; International Edition, 60(33), p.17871 - 17874, 2021/08
Times Cited Count：5 Percentile：20.14(Chemistry, Multidisciplinary)The formation and the chemical characterization of single atoms of dubnium (Db, element 105), in the form of its volatile oxychloride, was investigated using the on-line gas phase chromatography technique, in the temperature range 350 - 600 
C. Under the exact same chemical conditions, comparative studies with the lighter homologs of group-5 in the Periodic Table clearly indicate the volatility sequence being NbOCl
TaOCl
DbOCl. From the obtained experimental results, thermochemical data for DbOCl were derived. The present study delivers reliable experimental information for theoretical calculations on the chemical properties of transactinides.
1 surfaces studied using core-level X-ray photoelectron spectroscopyKakiuchi, Takuhiro*; Yamasaki, Hideki*; Tsukada, Chie*; Yoshigoe, Akitaka
Surface Science, 693, p.121551_1 - 121551_8, 2020/03
Times Cited Count：4 Percentile：17.41(Chemistry, Physical)We investigated the initial oxidation of ultrathin hafnium (Hf) film on Si(100)-21 using photoelectron spectroscopy. Metallic Hf rapidly oxidized, transforming into hafnium dioxide (HfO
) and its suboxides. The other HfSi component at the interface was nearly unreactive with O molecules. These facts suggest that the metallic Hf component plays a vital role in the initial oxidation of the ultrathin Hf/Si(100) film. After annealing from 873 K to 973 K, the Hf suboxides in low ionic valences progressed into fully oxidized HfO. Once the annealing temperature reached c.a.1073 K, oxygen atoms were entirely removed from the ultrathin HfO/Si(100) film containing SiO at the interface. Simultaneously, ultrathin HfO layers changed into islands of Hf disilicide (
-HfSi) on a bare Si(100)-21 surface. The -HfSi component showed slight reactivity with O molecules at 298 K. In contrast to the initial oxidation of clean Si(100)-21 surface, the dangling bonds on bare Si(100)-21 surface among -HfSi oxidized preferentially.
Chiera, N. M.; Sato, Tetsuya; Tomitsuka, Tomohiro; Asai, Masato; Ito, Yuta; Shirai, Kaori*; Suzuki, Hayato; Tokoi, Katsuyuki; Toyoshima, Atsushi; Tsukada, Kazuaki; et al.
Journal of Radioanalytical and Nuclear Chemistry, 320(3), p.633 - 642, 2019/06
Times Cited Count：2 Percentile：15.49(Chemistry, Analytical)An isothermal gas-chromatographic (IGC) device has been developed and tested for on-line gas phase studies of volatile oxychlorides of short-lived group-5 transition metals. Radioisotopes of niobium and tantalum, produced in nuclear fusion evaporation reactions, are directly flushed into the IGC setup by an inert gas-jet. Oxychloride compounds are formed by the addition of SOCl
and O. Parameters influencing the formation and transport of NbOCl and TaOCl are investigated. For nuclides with half-lives (
) of about 30 s, an overall efficiency of 7% is obtained, rendering the IGC setup suitable for the chemical exploration of 
Db( = 34s).
Chiera, N. M.; Sato, Tetsuya; Tomitsuka, Tomohiro; Asai, Masato; Suzuki, Hayato*; Tokoi, Katsuyuki; Toyoshima, Atsushi; Tsukada, Kazuaki; Nagame, Yuichiro
Inorganica Chimica Acta, 486, p.361 - 366, 2019/02
Times Cited Count：6 Percentile：28.92(Chemistry, Inorganic & Nuclear)The formation of NbOCl and TaOCl and their adsorption behavior on quartz surfaces was explored by applying an isothermal gas-chromatographic method. Trace amounts of short-lived Nb and Ta isotopes were used. Adsorption enthalpy values (
) at zero surface coverage of -(NbOCl) = 102 
4 kJ/mol and -(TaOCl) = 128 5 kJ/mol were determined by analyzing the chromatographic behavior of the Nb andTa complexes with a Monte-Carlo simulation method based on an adsorption-desorption kinetic model.By applying an empirical correlation, the experimental values were successively related to the macroscopic standard sublimation enthalpy, 
, as a measure of the volatility of each substance. The inferred sublimation enthalpies are in agreement with tabulated thermochemical values. Thus, the linear empirical correlation between and for metal-oxychlorides was updated with the inclusion of the present data. According to the predicted (DbOCl), a (DbOCl) value of 135 2 kJ/mol was extrapolated. The future accomplishment of comparative studies with DbOCl under the same experimental conditions will provide valuable information on the volatility trend in Group-5 elements, together with an indication on the magnitude of relativistic effects on the electronic structure of dubnium.
decomposition on Si(110)Yano, Masahiro; Uozumi, Yuki*; Yasuda, Satoshi; Asaoka, Hidehito; Tsukada, Chie*; Yoshida, Hikaru*; Yoshigoe, Akitaka
e-Journal of Surface Science and Nanotechnology (Internet), 16, p.370 - 374, 2018/08
reduction reaction region at void periphery on Si(110)Yano, Masahiro; Uozumi, Yuki*; Yasuda, Satoshi; Tsukada, Chie*; Yoshida, Hikaru*; Yoshigoe, Akitaka; Asaoka, Hidehito
Japanese Journal of Applied Physics, 57(8S1), p.08NB13_1 - 08NB13_4, 2018/07
Times Cited Count：2 Percentile：7.20(Physics, Applied)Eichler, R.*; Asai, Masato; Brand, H.*; Chiera, N. M.*; Di Nitto, A.*; Dressler, R.*; D
llmann, Ch. E.*; Even, J.*; Fangli, F.*; Goetz, M.*; et al.
EPJ Web of Conferences, 131, p.07005_1 - 07005_7, 2016/12
Times Cited Count：3 Percentile：69.95(Chemistry, Inorganic & Nuclear)In recent years gas-phase chemical studies assisted by physical pre-separation allowed for the productions and investigations of fragile single molecular species of superheavy elements. The latest highlight is the formation of very volatile hexacarbonyl compound of element 106, Sg(CO)
. Following this success, second-generation experiments were performed to measure the first bond dissociation energy between the central metal atom and the surrounding ligand. The method using a tubular decomposition reactor was developed and successfully applied to short-lived Mo(CO), W(CO), and Sg(CO).
Tokoi, Katsuyuki; Sato, Tetsuya; Eichler, R.*; Ito, Yuta; Tomitsuka, Tomohiro; Suzuki, Hayato*; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi*; Chiera, N. M.; et al.
no journal, ,
We developed a new experimental method combining vacuum chromatography and surface ionization, and applied this to investigate adsorption behavior of lawrencium (Lr, Z =103) on a surface of high temperature metallic tantalum. The adsorption behavior of Lr was similar to that of lutetium having low volatility among lanthanide elements. In this work, a Monte Carlo simulation code has been newly developed to study ionization and chromatographic behavior of short-lived atoms. In the presentation, we will report the details of a developed simulation code and calculation results.
Tsukada, Chie; Yoshida, Hikaru; Ogawa, Satoshi*; Yoshigoe, Akitaka; Yagi, Shinya*; Yaita, Tsuyoshi
no journal, ,
We focus on the Au nanoparticle, which is fabricated by solution plasma method, as the adsorbent with high density and high efficiency of Cs
in solution. To remove the Cs from the solution, we attempt two methods, which are the Cs adsorption on the Au nanoparticle surface and the interaction between the Cs and the L-cysteine on Au nanoparticle. Judging from the results of SR-XPS for the sample at the latter method, we suggest the interaction between the Cs and the COOH group of L-cysteine on Au nanoparticle.
Tsukada, Kazuaki; Toyoshima, Atsushi; Hirose, Kentaro; Asai, Masato; Chiera, N. M.; Tokoi, Katsuyuki; Suzuki, Shinichi; Kashihara, Ayuna*; Ninomiya, Hidemi*
no journal, ,
no abstracts in English
Tomitsuka, Tomohiro; Tokoi, Katsuyuki; Sato, Tetsuya; Ito, Yuta; Suzuki, Hayato*; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Chiera, N. M.; Goto, Shinichi*; et al.
no journal, ,
In order to experimentally determine the ground state electronic configurations of Superheavy element atoms, we have developed a slow Atomic Beam Source (ABS) using a high-temperature nozzle type cavity. In this study, we conducted an off-line experiment using stable isotopes of Cd to examine the extraction of the Cd beams. A symmetrical beam distribution with respect to the atomic beam edge was obtained. The obtained results, together with Monte-Carlo simulations for atomic beam profiles, will be presented.
Es targetAsai, Masato; Tsukada, Kazuaki; Hirose, Kentaro; Toyoshima, Atsushi; Tomitsuka, Tomohiro; Chiera, N. M.; Ito, Yuta; Makii, Hiroyuki; Nagame, Yuichiro; Nishio, Katsuhisa; et al.
no journal, ,
Spontaneous fissions of neutron-rich heavy actinide isotopes 
Fm, Fm, and 
Lr have been measured at the JAEA Tandem accelerator facility. Fm and Fm were produced in a multinucleon transfer reaction with an 
O beam and an extremely rare Es target with a half-life of 276 days. Reaction products were mass-separated with an on-line isotope separator (ISOL). A transition between the typical asymmetric mass distribution and a very sharp symmetric one was clearly observed between Fm and Fm, while the spontaneous fission of Lr was found to exhibit mixture of three different fission modes.
Asai, Masato; Tsukada, Kazuaki; Hirose, Kentaro; Toyoshima, Atsushi*; Tomitsuka, Tomohiro*; Chiera, N. M.*; Ito, Yuta; Makii, Hiroyuki; Nagame, Yuichiro*; Nishio, Katsuhisa; et al.
no journal, ,
We have studied spontaneous fission of neutron-rich Fm and Lr isotopes. The neutron-rich Fm isotopes were produced with the Es target and the O beam delivered by the JAEA tandem accelerator. The neutron-rich Lr isotope were produced with the 
Cm target and the 
N beam. Reaction products were mass-separated with an on-line isotope separator (ISOL), which enabled us to obtain non-contaminated samples and to measure fission fragments precisely. From the deduced fission-fragment mass and total kinetic energy distributions, we have obtained a new insight into the competition between the symmetric and asymmetric fission which is characteristic in this neutron-rich region.
Es targetAsai, Masato; Tsukada, Kazuaki; Hirose, Kentaro; Toyoshima, Atsushi; Tomitsuka, Tomohiro; Chiera, N. M.; Ito, Yuta; Makii, Hiroyuki; Nagame, Yuichiro; Nishio, Katsuhisa; et al.
no journal, ,
Spontaneous fissions of Fm, Fm, and Lr have been measured using an Es target at the JAEA Tandem Accelerator Facility. These three nuclei show different fission properties: the asymmetric fission, the high total-kinetic-energy (TKE) symmetric fission, and the low TKE symmetric fission, and the mechanisms of these three fissions should be very different. It is of great interest to elucidate how these differences occur. We have produced 
Fm in multinucleon-transfer reactions with a Es target and O projectiles, and produced Lr in the Cm(N,4n) fusion-evaporation reaction. The reaction products were mass-separated with a gas-jet-coupled on-line isotope separator, and were delivered into a rotating wheel alpha- and fission-fragment detection system. By comparing the mass and TKE distributions deduced from the present experimental data, we will discuss the differences in fission mechanism among Fm, Fm, and Lr.
Pd(111) surfaceTsuda, Yasutaka*; Makino, Takamasa*; Tsukada, Chie; Yoshigoe, Akitaka; Fukuyama, Tetsuya*; Okada, Michio*
no journal, ,
It is well-known that oxidation is an important chemical reactions in corrosion processes. CuPd has an attracting material due to its catalytic property and its oxidation is the important subject. In this presentation, initial oxidation processes at the CuPd(111) surface was studied by using molecular beams. In situ photoemission measurements were conducted using surface chemistry apparatus at BL23SU at SPring-8. Single crystal CuPd was used after cleaning by means of Ar ion sputtering and annealing. It was found that molecular beams facilitate oxidation compared to that for backfilling condition. Furthermore, diffusion of surface atoms seems to be driven with increasing surface temperature.
Cl on Si(100)21 by means of SR-XPSTsukada, Chie; Yoshida, Hikaru; Okada, Michio*; Yoshigoe, Akitaka; Yaita, Tsuyoshi
no journal, ,
To achieve Cs decontamination in clay minerals by using CHCl gas, we have investigated the adsorption reactions and adsorption states of CHCl at Si surfaces. In this conference, we report that dissociative adsorption of CHCl to form CH and Cl was revealed from the high energy-resolutions photoemission spectra.
H
on Cu(111) using supersonic CH molecular beamMakino, Takamasa*; Tsuda, Yasutaka*; Tsukada, Chie; Yoshigoe, Akitaka; Okada, Michio*
no journal, ,
Studies on the interaction between ethylene molecule and metal surfaces are the important subject to understand catalyitic reactions such as dehydrogenation. To clarify dissociation adsorption processes of ethylene at metal surfaces, the surface analysis after exposure of ethylene to Cu(111) surface was conducted by using synchrotron radiation XPS. We found the growth of peak intensities and the peak shifted to higher binding energy side when ethylene beams with the kinetic energy of 2 eV were irradiated at the surface temperature of 300 K. The adsorption states and surface temperature dependece of reactions will be discussed.
Md produced in the He+Es reactionNishio, Katsuhisa; Hirose, Kentaro; Makii, Hiroyuki; Orlandi, R.; Kean, K. R.*; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi*; Sato, Tetsuya; Ito, Yuta; et al.
no journal, ,
no abstracts in English
Md produced in the He + Es reactionNishio, Katsuhisa; Hirose, Kentaro; Makii, Hiroyuki; Orlandi, R.; Kean, K. R.*; Tsukada, Kazuaki; Toyoshima, Atsushi*; Asai, Masato; Sato, Tetsuya; Chiera, N. M.*; et al.
no journal, ,
no abstracts in English
