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Laboratory for Radiochemistry and Environmental Chemistry

Why experimenters like to come to Dubna: Scientific success is always a good reason to organize a big party!. Chemistry of volatile 7p-elements = chemistry of spherical SHE

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Laboratory for Radiochemistry and Environmental Chemistry

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  1. Why experimenters like to come to Dubna: Scientific success is always a good reason to organize a big party!

  2. Chemistry of volatile 7p-elements = chemistry of spherical SHE Recent studies with IVO: In-Situ volatilisation and On- line detection (developed for first chemical study of hassium but recently applied for element 112 and 114) Are relativistic effects influencing the chemical property of element 114? Laboratory for Radiochemistry and Environmental Chemistry How chemists have reached the island of spherical superheavy elementsHeinz W. GäggelerPaul Scherrer Institut andBern University, Switzerland

  3. island of SuperheavyElements 114 strait of insta- bility peak of U peak of Pb 82 strait of radioactivity Number of protons sea of instability 50 peak of Sn 20 sea of instability peak of Ca 82 126 184 20 Number of neutrons G.N. Flerov, A.S. Ilyinov (1982)

  4. Shell stabilisation spherical deformed Courtesy: S. Hofmann

  5. Elements Periodic Table of the Periodic Table of the 1 18 1 2 2 13 14 15 16 17 H He 3 4 5 6 7 8 9 10 Li Be B C N O F Ne 11 12 13 14 15 16 17 18 3 4 5 6 7 8 9 10 11 12 Na Mg Al Si P S Cl Ar 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 87 88 104 105 89 106 107 108 Bh Hs 114 Sg Fr Ra Ac Rf Db 112 109 110 111 114 116 116 115 113 118 116 115 113 118 Mt Ds Rg - - Ds Rg 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Lanthanides Lanthanides Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 90 91 92 93 94 95 96 97 98 99 100 101 102 103 Actinides Actinides Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

  6. Mendelejev‘s first Periodic Table from 1871 Basis for the discovery of several new elements!

  7. 108 114 112 106 107 - - - - Hs Sg Bh 108 109 112 106 107 - - Mt Sg Hs Bh 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Positioning of new elements into the Periodic table 1 18 1 2 H 2 13 14 15 16 17 He ≥ 2007 1993 - 1997 2001 - 2007 2000 2002 3 4 5 6 7 8 9 10 Li Be B C N O F Ne 11 12 13 14 15 16 17 18 Na Mg 3 4 5 6 7 8 9 10 11 12 Al Si P S Cl Ar 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 55 56 57-71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 87 88 104 105 89-103 Fr Ra Ac Rf Db 110 111 114 116 113 115 116 118 Rg - - - - Ds Lanthanides Actinides

  8. Reactions used and number of atoms found in the „first ever chemical studies“ in the last decade • Bohrium (Z=107); Main experiment at PSI249Bk(22Ne;4n)267Bh (T1/2 = 17 s); 6 atoms (R. Eichler et al., Nature, 407, 64 (2000)) • Hassium (Z=108); Main experiment at GSI248Cm(26Mg;5n)269Hs(T1/2 = 15 s); 7 atoms (C.E. Düllmann et al., Nature, 418, 860 (2002)) • Element 112; Main experiment at FLNR/JINR242Pu(48Ca,3n)287114 (T1/2 = 0.5 s)283112 (T1/2 = 4 s); 2 atoms (R. Eichler, Nature, 447, 72,2007); meanwhile 5 atoms in total (R. Eichler et al., Angew. Chem. Int. Ed., 47,1(2008)) • Element 114: Main experiment at FLNR/JINR; ongoing. Currently evidence for 3 - 5 atoms

  9. Gas flow IsothermalChromatography: Sg,Bh Gas flow T 50% tRet. = T1/2 Yield [%] Temperature [°C] Temperature [°C] low high Column length [cm] Thermochromatography: Hs, Z=112; Z=114 T a Temperature [°C] Yield [%] Column length [cm] Temperature [°C] high low

  10. Elements with Z ≥ 112: filled 6d10 shell: 7p-element behaviour (volatile noble metals) 1 18 1 2 2 13 14 15 16 17 H He 3 4 5 6 7 8 9 10 Li Be B C N O F Ne 11 12 13 14 15 16 17 18 3 4 5 6 7 8 9 10 11 12 Na Mg Al Si P S Cl Ar 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 87 88 104 105 89 106 107 108 Bh Hs 114 Sg Fr Ra Ac Rf Db 112 109 110 111 114 116 116 115 113 118 116 115 113 118 Mt Ds Rg - - Ds Rg 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Lanthanides Lanthanides Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 90 91 92 93 94 95 96 97 98 99 100 101 102 103 Actinides Actinides Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

  11. How to experimentally determine a metallic character of a volatile element at a single atom level? → Determine interaction energy (adsorption enthalpy) with noble metals (e.g. Au) → If metallic: strong interaction (adsorption enthalpy) if non-metallic (noble gas like): weak interaction

  12. 50 500 45 450 192Hg Hads = -87 kJ/mol 40 400 219Rn Hads = -27 kJ/mol 35 350 30 300 yield [%] temperature [K] 25 250 20 200 15 150 10 100 5 50 0 0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 lenght [cm] Adsorption of single atoms of mercury and radon on a gold surface

  13. 60 500 450 192Hg Hads = -24.5 kJ/mol 50 400 219Rn Hads = -20.5 kJ/mol 350 40 300 yield [%] temperature [K] 30 250 200 20 150 100 10 50 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 lenght [cm] Adsorption of single atoms of mercury and radon on a quartz surface

  14. Correlation between adsorption properties of single atoms on gold and their macroscopic sublimation enthalpy

  15. Element 112 similar to Hg? 1 18 1 2 2 13 14 15 16 17 H He 3 4 5 6 7 8 9 10 Li Be B C N O F Ne 11 12 13 14 15 16 17 18 3 4 5 6 7 8 9 10 11 12 Na Mg Al Si P S Cl Ar 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 87 88 104 105 89 106 107 108 112 114 Bh Hs Sg Fr Ra Ac Rf Db 109 110 111 114 116 116 115 113 118 116 115 113 118 Mt Ds Rg - - Ds Rg 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Lanthanides Lanthanides Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 90 91 92 93 94 95 96 97 98 99 100 101 102 103 Actinides Actinides Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Texas A&M, Nov. 2007

  16. The element 112 experiment (IVO [In-situ Volatilisation and On-line detection]Technique) Beam (48Ca; 233-239 MeV) Teflon capillary Window/ Target (242Pu: 1.4 mg/cm2) Cryo On-line Detector (4p COLD) SiO2-Filter Ta metal 850°C (32 pairs PIN diodes, one side gold covered) 112 Loop Rn Hg Quartz inlay Recoil chamber Temperature gradient: 35°C to – 184 °C Quartz column Beam stop T Carrier gas He/Ar (70/30) l

  17. Studies on element 112 • 242Pu(48Ca;3n)287114 (0.5 s) → 4s 283112 • Reasons a) High cross section of  5 pb ( 3-times higher than via direct production with 238U as a target) • b) Residence time in collection chamber and transport capillary  2 s 283112 4 s a 9.54 MeV Rf 261 Ds 279 4 s 0.2 s a 8.5 MeV Trends in heavy ion science, 24 May 2008

  18. Excitation functions Excitation functions xn-channel cross sections from 242,244Pu+48Ca reactions Courtesy: Yu. Oganessian. “Heaviest Nuclei from 48Ca-induced Reactions” TAN-07, Davos, Sept. 23-27, 2007 Trends in heavy ion science, 24 May 2008

  19. Observed in Chemistry: 11.05.2006 2:40 (moscow time) 25.05.2006 8:37 (moscow time) 287114 287114 283112 9.37 MeV 283112 9.48 MeV 279Ds t: 0.592 s SF 108+123 MeV 279Ds t:0.536 s SF 127+105 MeV Laboratory for Radiochemistry and Environmental Chemistry Result from the 48Ca + 242Pu experiment First independent confirmation of 283112 formation and decay properties! (R. Eichler et al., Nature, 447, 72 (2007)) Three week bombardment with 3.1x101848Ca ions at 236 ± 3 MeV

  20. 287114 287114 287114 283112 9.52 MeV 283112 9.52 MeV 283112 9.35 MeV 279Ds t: 0.072 s SF 112 + n.d MeV 279Ds t: 0.088 s SF 94+51 MeV 279Ds t:0.773 s SF85+12 MeV Result from additional 48Ca + 242Pu experiments in 2007 The chemistry experiment is not sensitive to the 4n channel (too short-lived nuclides) Bombardment 21.3.- 17.4. 2007 with 3.1x101848Ca ions at 237± 3 MeV

  21. The chemistry of element 112 Element 112 is similar to Hg, but slightly more volatile Deduced adsorption enthalpy: -52+20-4 kJ/mol (black solid line)

  22. The chemistry of element 112 -52+20-4 kJ/mol DHsubl=39+23-10 kJ/mol (68% c.i.)

  23. Trend of sublimation enthalpy within group 12

  24. Search for relativistic effects in the chemistry of element 114 (group 14 with [Rn]7s26d107p2) Relativistic effect: influence of increasing Coulomb attraction between atomic electrons and nucleus What‘s next?

  25. Group 14: 6d107s27p2 Prediction by Pitzer (1975) Is element 114 a noble gas due to a strong spin-orbit splitting of the 7p orbitals? from: V. Pershina et al., J. Chem. Phys., 127, 134310 (2007)

  26. Studies on element 114 • Reaction: 242Pu(48Ca;3n)287114 (T1/2 =0.5s) (FLNR; spring 2007) 287114 1 atom on Au at – 80 °C a 10.0 MeV 3.1x101848Ca ions at 237± 3 MeV 283112 10.9 s a 9.54 MeV Rf 261 Ds 279 4 s 0.24s a 8.5 MeV unpublished Trends in heavy ion science, 24 May 2008

  27. Studies on element 114 • Reaction: 244Pu(48Ca;4n)288114 (T1/2 =0.8s) 2 atoms on Au at –10 °C & -84 °C Beam dose 4x1018Energy within targets: 243 – 231 MeV(~ 1.4 mg/cm2) 288114 288114 a 9.81 MeV a 9.95 MeV Rf 261 284112 284112 4 s 0.11 s 0.11 s a 8.5 MeV unpublished Trends in heavy ion science, 24 May 2008

  28. Current experiment lasting until 8 June 2008 at FLNR:48Ca + 244Puto produce0.8 s 288114 (4n-channel)2.7 s 289114 (3n-channel) Chemistry behind the Dubna gas-filled separator

  29. Pro & Contra • Pro:- Extremely clean a- spectra (no background)- no sf-contamination by sputtered target • Contra:- Lower efficiency- Smaller energy range in the thin target

  30. Studies on element 114 • Reaction: 244Pu(48Ca;3n)289114 (T1/2 =2.7s) (FLNR; ongoing 2008) 289114 Not detected 1 atom on Au at – 97 °C 285112 4x101848Ca ions at E* = 38 – 42 MeV a 9.12 MeV Rf 261 281Ds 4 s 3.3s a 8.5 MeV SF 106+50 unpublished Trends in heavy ion science, 24 May 2008

  31. Preliminary Decay during transport? unpublished

  32. Preliminary E114

  33. Result from the chemistry experiment with element 114 → Element 114 exhibits a very weak adsorption on Au, pointing to van der Waals interaction (similar to a noble gas).

  34. Conclusion • Chemical research on heaviest elements has been much boosted by the recent discoveries of many new nuclides up to Z=118 at FLNR • Chemical studies at the few atom level have been sucessfully conducted up to Z = 112 • Elements Bh, Hs & 112 (as well as Rf, Db, Sg) behave in gas phase studies as expected from extrapolations within the groups of the periodic table • Ongoing studies point to an element 114 behaviour unlike that of eka-Pb, but rather similar to a noble gas. Trends in heavy ion science, 24 May 2008

  35. Many thanks • To Yuri Oganessian for his constant support and very active engagement in the experiments • To Sergei Dmitriev and his team for the Dubna chemists • To Georgi Gulbekian and his team for the excellent 48Ca beams • To Robert Eichler and his team from the PSI/Univ. Bern collaboration Trends in heavy ion science, 24 May 2008

  36. Raw data from few-hour measurement with pre-separation (GNS) (left) and without (right) 215Po 219Rn 214Po 212Po 211At

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