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Journal Articles

First ionization potentials of Fm, Md, No and Lr; Verification of filling-up of 5f electrons and confirmation of the actinide series

Sato, Tetsuya

Kagaku To Kogyo, 72(10), P. 867, 2019/10

We conducted measurements of the first ionization potential (IP$$_1$$) of the heavy actinide elements, lawrencium (Lr, $$Z = 103$$), nobelium (No, $$Z = 102$$), mendelevium (Md, $$Z = 101$$) and fermium (Fm, $$Z = 100$$) by using a novel method based on a surface ionization process. The IP$$_1$$ measurements have been performed using the ISOL (Isotope Separator On-Line) system equipped with a surface ion-source with short-lived heavy actinide isotopes, $$^{256}$$Lr ($$T_{1/2}$$ = 27s), $$^{257}$$No ($$T_{1/2}$$ = 24.5s), $$^{251}$$Md ($$T_{1/2}$$ = 4.27 min), and $$^{249}$$Fm ($$T_{1/2}$$ = 2.6 min). Our experimental results clearly showed that the IP$$_1$$ of Lr is distinctly low among actinide elements. Moreover, No has the highest IP$$_1$$ among them due to its full-filled 5f and 7s orbitals; the IP$$_1$$ value increased with an atomic number up to No and decreased dramatically at Lr, indicating the similar trend with that of heavy lanthanide elements. Therefore, we concluded Lr would be the last member of the actinide series.

Journal Articles

First ionization potential of the heaviest actinide lawrencium, element 103

Sato, Tetsuya; Asai, Masato; Borschevsky, A.*; Stora, T.*; Sato, Nozomi*; Kaneya, Yusuke; Tsukada, Kazuaki; D$"u$llmann, C. E.*; Eberhardt, K.*; Eliav, E.*; et al.

EPJ Web of Conferences, 131, p.05001_1 - 05001_6, 2016/12

 Times Cited Count:0 Percentile:0.00(Chemistry, Inorganic & Nuclear)

Ionization efficiency in a surface ionization process depends on the first ionization potential of the atom. Based on the dependence, the ionization potential of the atom can be determined. We measured ionization efficiencies of fermium, einsteinium, mendelevium, and lawrencium by using a newly developed gas-jet coupled surface ion-source. The ionization potential of the elements have not been determined so far due to their low production rates and/or their short half-lives. Based on a relationship between the ionization efficiency and the ionization potential obtained via measurements of short-lived lanthanide isotopes, the ionization potentials of these actinide elements have been successfully determined.

Journal Articles

Measurement of the first ionization potential of lawrencium by surface ionization method

Sato, Tetsuya

Genshikaku Kenkyu, 61(1), p.96 - 106, 2016/09

We successfully determined the first ionization potential of lawrencium (Lr, Z=103). The result experimentally substantiated for the first time that Lr is the last member of the actinide series. Measured ionization potential suggested that Lr atom would have the electronic configuration which is different from the configuration expected based on the Periodic table. For the measurement, we have developed a novel method applied the surface ionization process. Public responses after the publication are also introduced.

Journal Articles

Does element-103 change the periodic table of elements ?!; The First ionization potential of lawrencium

Sato, Tetsuya

Kagaku, 71(3), p.12 - 16, 2016/03

We successfully confirmed that lawrencium, element 103, would be the last member of actinide series by a measurement of the first ionization potential of lawrencium. Moreover, the electronic configuration expected from the experimental results suggested that lawrencium could have the outermost electronic orbital similar to that of group-13 elements. Our result triggered discussion concerning the position of lawrencium and lutetium on the periodic table of the elements.

Journal Articles

Lawrencium's place at the table

Nagame, Yuichiro

Nature Chemistry, 8(3), P. 282, 2016/03

We summarize the studies of element 103, lawrencium: discovery or synthesis in nuclear reactions, historical argument for recognition as a new element, nuclear and chemical studies of lawrencium isotopes, and recently measured ionization energy. Based on the studies so far performed, we introduce a debate that has emerged over the place in the periodic table.

Journal Articles

The First ionization potential of element 103 successfully measured for the first time substantiated that lawrencium is the last member of actinide series

Sato, Tetsuya

Isotope News, (740), p.16 - 19, 2015/12

We successfully determined the first ionization potential of lawrencium (Lr, Z=103). The result experimentally substantiated for the first time that Lr is the last member of the actinide series. Measured ionization potential suggested that Lr atom would have the electronic configuration which is different from the configuration expected based on the Periodic table.

Journal Articles

Where is an appropriate place for element 103 on the periodic table?; Measurement of the first ionization potential of lawrencium

Sato, Tetsuya

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 57(11), p.741 - 744, 2015/11

We have experimentally confirmed that Lr would be the last member of actinides series for the first time by a measurement of the first ionization potential of lawrencium (Lr, element 103). The electronic orbital of Lr atom which is estimated by the result suggests that Lr could have the outermost electronic orbital similar with group-13 elements. This work triggered a discussion concerning positions of Lr and lutetium, lanthanide homologue of Lr.

Journal Articles

Measurement of the first ionization energy of lawrencium (Z = 103) by surface ionization technique

Sato, Tetsuya

Hosha Kagaku, (32), p.34 - 41, 2015/09

In the surface ionization process, an ionization efficiency depends on the first ionization potential of the atom of the element. The ionization potential can be estimated by using the relationship. This method has been developed in order to determine the first ionization potential of lawrencium (Lr, element 103). The value of the ionization potential of Lr have not been measured experimentally due to its low production rate and short half-life. The surface-ionization method is described in detail in this paper.

Journal Articles

Discrepancy in the periodic table appears at element 103; Successful measurement of the first ionization potential of lawrencium, element 103

Sato, Tetsuya; Nagame, Yuichiro; Tsukada, Kazuaki

Kagaku To Kogyo, 68(9), p.824 - 826, 2015/09

We successfully confirmed that lawrencium (Lr, element 103) is the last member of actinide series by a measurement of its first ionization potential. Obtained experimental result suggested that the outermost electronic orbital of Lr atom would have p-orbital similar to elements of group-13. Our result triggered again the discussion of the position of Lr and lutetium, the lanthanide homologue of Lr, on the Periodic Table.

Journal Articles

Successful measurement of the first ionization potential of lawrencium, element 103

Sato, Tetsuya

Saiensu Potaru (Internet), 3 Pages, 2015/07

On April 9th, a press release titled "Measurement of the first ionization potential of lawrencium (element 103) - Unravelling Relativistic Effects in the Heaviest Actinide Element -" was issued. This research result published from Nature was not only introduced in its "News & Views" but also appeared on the cover. I made a commentary on the result and introduced its response for public.

Journal Articles

Measurement of the first ionization potential of lawrencium, element 103

Sato, Tetsuya; Asai, Masato; Borschevsky, A.*; Stora, T.*; Sato, Nozomi; Kaneya, Yusuke; Tsukada, Kazuaki; D$"u$llmann, Ch. E.*; Eberhardt, K.*; Eliav, E.*; et al.

Nature, 520(7546), p.209 - 211, 2015/04

 Times Cited Count:112 Percentile:97.06(Multidisciplinary Sciences)

Ionization efficiency in a surface ionization process depends on the first ionization potential of the atom. Based on the dependence, the ionization potential of the atom can be determined. We successfully measured ionization efficiencies of lawrencium (Lr, $$Z$$=103) using a gas-jet coupled surface ion-source. The ionization potential of Lr has not been determined owing to its low production rate and its short half-life. Based on a relationship between the ionization efficiency and the ionization potential obtained via measurements of short-lived lanthanide isotopes, the ionization potential of Lr was determined.

Oral presentation

First ionization energy measurements of heaviest actinides, lawrencium and nobelium

Sato, Tetsuya

no journal, , 

We measured the first ionization energy (IE$$_1$$) of nobelium (No, Z = 102) and lawrencium (Lr, Z =103) by exploiting the dependence of the ionization efficiency ($$I_{rm eff}$$) on the IE$$_1$$ in a surface ionization process. The isotopes $$^{257}$$No ($$T_{1/2}$$ = 24.5s) and $$^{256}$$Lr ($$T_{1/2}$$ = 27 s), produced in the reaction $$^{248}$$Cm ($$^{13}$$C, 4n) and $$^{249}$$Cf ($$^{11}$$B, 4n), respectively, were used for studying their ionization. The reaction products recoiling from the targets were transported to a surface ion-source by a He/CdI$$_2$$ gas-jet transport system. The products ionized in the ion-source were mass-separated with JAEA-ISOL. The number of ions collected at the end of the ISOL was determined by $$alpha$$-particle measurements and was used to evaluate $$I_{rm eff}$$ values. With the present system, we successfully ionized and mass-separated $$^{257}$$No and $$^{256}$$Lr with efficiencies of (0.5 $$pm$$ 0.1)% and (36 $$pm$$ 7)% at 2800 K, respectively. From these $$I_{rm eff}$$ values, IE$$_1$$ values of No and Lr were determined based on the relationship between $$I_{rm eff}$$ and IE$$_1$$. Our values are in good agreement with the predicted ones by theoretical calculations.

Oral presentation

Measurement of the ionization potential of Lr (Z = 103) by online mass separation

Sato, Tetsuya; Stora, T.*; Asai, Masato; Borschevsky, A.*; Kaneya, Yusuke; Tsukada, Kazuaki; D$"u$llmann, Ch. E.*; Eliav, E.*; Kaldor, U.*; Kratz, J. V.*; et al.

no journal, , 

It is known that an ionization efficiency of an element in surface ionization process depends on temperature, work function of the surface, and the first ionization energy of the atom of the element to be ionized. We determined the first ionization energy of lawrencium (Lr), the last member of the actinide series, using the relationship between the ionization efficiency and the ionization energy. The ionization energy of Lr had not been measured owing to its low production rate and short half-lives so far. The experimental value of the ionization energy is in good agreement of the theoretical one which was calculated using the state-of-the-art relativistic calculation.

Oral presentation

Discrepancy in the periodic table appears at element 103; The Periodic table of elements might be restructured

Sato, Tetsuya

no journal, , 

The first ionization potential (IP$$_1$$) of element 103, lawrencium (Lr), has been successfully determined for the first time by using a newly developed method based on a surface ionization process. The measured IP$$_1$$ value is 4.96 $$pm$$ 0.08 eV. This value is the smallest among those of actinide elements and is in excellent agreement with the value of 4.963(15) eV predicted by state-of-the-art relativistic calculations also performed in this work. Our results strongly support that the Lr atom has an electronic configuration of [Rn]$$7s^25f^{14}7p_{1/2}$$, which is influenced by strong relativistic effects. The present work opens the way for studies on atomic properties of heavy elements with atomic number $$Z > 100$$. Moreover, the present achievement has triggered a controversy on the position of lutetium (Lu) and Lr in the Periodic Table of Elements.

Oral presentation

Development of low energy atomic beam extraction technique for determination of valence electronic structure of Lawrencium (Z = 103)

Tomitsuka, Tomohiro; Tokoi, Katsuyuki*; Sato, Tetsuya; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Chiera, N. M.; Kamada, Hiroki; Nagame, Yuichiro; Goto, Shinichi*

no journal, , 

no abstracts in English

Oral presentation

Is the periodic table rewritten?; A Discrepancy on the periodic table which is found at the last element of actinide series

Sato, Tetsuya

no journal, , 

In order to clarify the properties of heavy actinide elements, we focused on the first ionization potential (IP$$ _1 $$), which is a physical quantity that directly reflects the binding energy of the outermost electron. To obtain information about the electron configuration of heavy actinide elements including element 103, lowrencium (Lr), the IP$$ _1 $$ of fermium (Fm), mendelevium (Md), nobelium (No) and Lr were determined experimentally by using a novel method we have developed based on the surface ionization. From the results, it was clarified that No would have the quasi-closed shell structure [Rn]7s$$^2$$5f$$^{14}$$ and Lr would have one loosely-bound electron in the outermost electron orbital. We showed for the first time that the actinide series ends at Lr experimentally.

Oral presentation

Chemical & atomic studies of the heaviest elements with JAEA-ISOL; Measurements of the first ionization potentials and study of thermochemical properties

Sato, Tetsuya

no journal, , 

The chemical and atomic properties of the heavy elements with atomic numbers Z $$>$$ 100, affected by strong relativistic effects, are studied at an-atom-at-a-time scale using the JAEA-ISOL. We successfully determined the first ionization potential (IP$$_1$$) values of heavy actinide elements from fermium (Fm, Z = 100) to lawrencium (Lr, Z = 103) by using a surface ion-source installed in the Isotope Separator On-Line (ISOL) at the JAEA tandem accelerator facility. The adsorption behavior of Lr is being studied by a newly developed method combining vacuum chromatography with surface ionization in a metallic column/ionizer of the ISOL as well.

Oral presentation

Monte Carlo simulation of surface ion-source for adsorption study of lawrencium, element 103

Sato, Tetsuya; Nagame, Yuichiro*; Eichler, R.*

no journal, , 

Element 103, lawrencium (Lr) has been pointed out that it might have significantly high volatility more than that of lutetium (Lu), the lanthanide homolog of Lr, owing to an influence of the strong relativistic effect. In our previous work, we have measured the first ionization potential of Lr by using the surface ionization method. In the method, the Lr atom was surface ionized on a tantalum surface at a high temperature. If the surface temperature is sufficiently high, the ionization efficiency of Lr can be estimated by the Saha-Langmuir (S-L) equation. However, an adsorption loss of the atoms of interest onto the metal surface could be inevitable at a low temperature. In that case, the apparent ionization efficiency would become smaller than the value predicted from the S-L equation. We have developed a Monte Carlo simulation code to estimate the adsorption loss of atoms on the ion-source surface in this work. The simulation code describes the ionization behavior of the atoms by combining the thermal ionization process in the ionizer and the adsorption-desorption process on the surface.

Oral presentation

Adsorption behavior of lawrencium (Lr, Z = 103) on a tantalum surface

Sato, Tetsuya; Kaneya, Yusuke*; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Mitsukai, Akina*; Osa, Akihiko; Makii, Hiroyuki; Hirose, Kentaro; Nagame, Yuichiro; et al.

no journal, , 

Our experimental results on the first ionization potential measurement of lawrencium (Lr, element 103) have strongly suggested that the Lr atom has a [Rn]$$7s^25f^{14}7p_{1/2}$$ configuration as a result of the influence of strong relativistic effects. The configuration is different from that expected from the lanthanide homologue, lutetium (Lu). According to a semi-empirical consideration, it is expected that the change of the electronic configuration leads higher volatility of Lr than that of Lu. In this work, adsorption behaviors of Lr and various short-lived rare earth isotopes on a tantalum surface were investigated via observation of their surface ionization efficiencies. It was found that Lr would behave like low volatile rare earth elements such as Lu contrary to the semi-empirical expectation.

Oral presentation

Adsorption of Lawrencium (Z = 103) on a tantalum surface

Tomitsuka, Tomohiro; Kaneya, Yusuke*; Sato, Tetsuya; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Mitsukai, Akina; Osa, Akihiko; Nishio, Katsuhisa; Nagame, Yuichiro; et al.

no journal, , 

In order to investigate the adsorption behavior of Lawrencium (Lr, Z = 103) on a Tantalum (Ta) surface, we measured ionization efficiencies of Lr under several temperature conditions of the surface ionization. We observed ionization efficiencies of Lr which were lower than those calculated by the Saha-Langmuir equation in lower temperature region. Based on a temperature dependence of the obtained ionization efficiencies, we discuss the adsorption behavior of Lr on the Ta surface.

27 (Records 1-20 displayed on this page)