Mendeleev; Dubna 2009 Mendeleev’s principle against Einsteins relativity news from the chemistry of superheavy elements H.W. Gäggeler  Reminiscences: from Mendelejeev’s periodic table to the discovery of mendelevium, the last “real” chemical element  Positioning four new chemical elements into the periodic table during the last decade. Mendelejeevs dreams become true!  How reliable is single atom chemistry? Proof of principle with elements Hs and 112  Einsteins influence on the chemistry of heaviest elemenst, so far up to Z=114 Laboratory for Radiochemistry and Environmental Chemistry

Mendelejeev‘s „second“ Periodic Table from 1871 D.I. Mendeleev (8 Feb – 2 Feb. 1907)

Predictions by Mendeleev in 1871 Eka-Al: Discovered by P.E. Lecoq de Boisbaudran in 1875, named Ga Eka-Al: Discovered by P.E. Lecoq de Boisbaudran in 1875, named Ga Eka-B: Discovered by L.F. Nilson in 1879, named Sc Eka-B: Discovered by L.F. Nilson in 1879, named Sc Eka-Si: Discovered by C. Winkler in 18886, named Ge Eka-Si: Discovered by C. Winkler in 18886, named Ge

Major refinements Noble gases: Sir William Ramsey (1894) Noble gases: Sir William Ramsey (1894) Henry Moseley: Atomic number, determined via X-rays, defines ordering of elements (1914) Henry Moseley: Atomic number, determined via X-rays, defines ordering of elements (1914) Glenn T. Seaborg: Actinides series (1945) Glenn T. Seaborg: Actinides series (1945)

Periodic Table in the 1930‘s G.T. Seaborg, W. D. Loveland (1990)

H Li Na K Rb Cs FrRaAc Ba Sr Ca Mg Be Sc Y La Ti Zr Hf V Nb Ta Cr Mo W Mn Tc Re Fe Ru Os CoNiCuZnGaGeAs RhPdAgCdInSnSb IrPtAuHgTlPbBi RfDb BCNOF AlSiPSCl SeBr TeI PoAt Lanthanides Actinides 114 He Ne Ar Kr Xe Rn CePrNdPmSmEuGdTbDyHoErTmYbLu ThPaUNpPuAmCmBkCfEsFmMdNoLr La Ac Periodic Table today Mt Ds 111 Rg Sg 106 Bh 107 Hs

Courtesy: Yu.Ts. Oganessian

Mendeleev, Dubna 2009 Discovery of new elements – the failure of chemistry! The heaviest element discovered purely by chemical means: Mendelevium! (1955) → Synthesis: bombardment of 253 Es with  -particles. → Collection of products in a foil. → Separation of products after dissolution of foil on a cation exchange column with  -HIB

Elution of actinides on a cation exchange column by  -HIB Elution in drops Count rate [cpm]

Mendeleev, Dubna 2009 Discovery of Mendelevium on the basis of 7 atoms A. Ghiorso et al., Phys. Rev. 98, 1518 (1955) Fm Es Cf unknown

H Li Na K Rb Cs FrRaAc Ba Sr Ca Mg Be Sc Y La Ti Zr Hf V Nb Ta Cr Mo W Mn Tc Re Fe Ru Os CoNiCuZnGaGeAs RhPdAgCdInSnSb IrPtAuHgTlPbBi RfDb BCNOF AlSiPSCl SeBr TeI PoAt Lanthanides Actinides He Ne Ar Kr Xe Rn CePrNdPmSmEuGdTbDyHoErTmYbLu ThPaUNpPuAmCmBkCfEsFmMdNoLr La Ac Positioning of new elements during the last decade Bh 107 Hs 108 Mt Ds 111 Rg Sg Bh 107 Hs Techniques developed at PSI and Bern University ?2009?

Mendeleev, Dubna 2009 Reactions used and number of atoms found in the „first ever chemical studies“ during the last decade Bohrium (Z=107); Main experiments at PSI 249 Bk( 22 Ne;4n) 267 Bh (T 1/2 = 17 s); 6 atoms (R. Eichler et al., Nature, 407, 64 (2000)) Hassium (Z=108); Main experiments at GSI 248 Cm( 26 Mg;5n) 269 Hs (T 1/2 = 15 s); 7 atoms (C.E. Düllmann et al., Nature, 418, 860 (2002)) Element 112; Main experiments at FLNR/JINR 242 Pu( 48 Ca,3n) (T 1/2 = 0.5 s)  (T 1/2 = 4 s); 2 atoms (R. Eichler et al., Nature, 447, 72 (2007)). Confirmed with 3 additional atoms (R. Eichler et al., Angew. Chem. Int. Ed., 47(17), 3262 (2008) Element 114: Main experiments at FLNR/JINR 242,244 Pu( 48 Ca;3,4n) 287,288, (T 1/2 = 0.5s;0.8s;2.6s); 3 – 4 atoms (R. Eichler et al.,submitted to Nature (2008)).

Mendeleev, Dubna 2009 How reliable is single atom chemistry? 1 st example: hassium chemistry Investigation of hassium in form of its very volatile molecule HsO 4 Applied technique: Thermochromatography

Thermochromatography T=100K T=300K detectors Result: T dep   H ads Temperature gradient T yield length Internal chromatogram T dep

Detector Rel. Yield [%] Temperature [°C] Exp: 269 Hs (T 1/2 =9.7 s) Exp: 172 Os (T 1/2 =19.2 s) MCS (Os): kJ/mol MCS (Hs): kJ/mol Temperature profile -82±5 °C -44±5 °C HsO 4 OsO 4 Thermochromatography of OsO 4 and HsO 4 C.E. Düllmann et al., Nature 418,860 (2002) 1 atom 4 atoms 2 atoms

Mendeleev, Dubna 2009 Nobel Laureate Glenn T. Seaborg, The first human being, able to celebrate „his“ element!

Mendeleev, Dubna 2009 How reliable is single atom chemistry? 2 nd example: element 112 Element 112 presumably is highly volatile so that it can be separated and analysed in elemental form Applied technique: Thermochromatography

H Li Na K Rb Cs FrRaAc Ba Sr Ca Mg Be Sc Y La Ti Zr Hf V Nb Ta Cr Mo W Mn Tc Re Fe Ru Os CoNiCuZnGaGeAs RhPdAgCdInSnSb IrPtAuHgTlPbBi RfDb BCNOF AlSiPSCl SeBr TeI PoAt Lanthanides Actinides 114 He Ne Ar Kr Xe Rn CePrNdPmSmEuGdTbDyHoErTmYbLu ThPaUNpPuAmCmBkCfEsFmMdNoLr La Ac Periodic Table today Mt Ds 111 Rg Sg 106 Bh 107 Hs

Trend of sublimation enthalpy within group 12 ? Mendeleev says: 112 an even more volatile metal compared to Hg!

However,….. Pitzer (1975) says: because of relativistic effects element 112 could well behave like a noble gas. Reason: E112 has a filled 6d 10 7s 2 electronic shell configuration

Relativistic effects High atomic number: strong Coulomb attraction causes electrons to move faster. Causes relativistic mass increase [m=m 0 (1-   )], with  v/c; and, as a consequence, contraction of spherical orbitals (ns, np 1/2 ) Energy levels of spherical orbitals are increased Energy levels of high angular momentum orbitals are destabilized due to shielding effects by spherical orbitals Strong spin-orbit splitting

Example: the relativistic 6s/7s contraction in Au and Rg Consequence: Cu, Ag, Au nd 10 (n+1)s 1 Zn +,Cd +,Hg + however: Rg, nd 9 (n+1)s 2 ( 2 D 5/2 ) E.Eliav, U.Kaldor, P.Schwerdtfeger, B.Hess, Y.Ishikawa, Phys. Rev. Lett. 73, 3203 (1994). M.Seth, P.Schwerdtfeger, M.Dolg, K.Faegri, B.A.Hess, U.Kaldor, Chem. Phys. Lett. 250, 461 (1996). Courtesy:P. Schwerdtfeger

direct effect (contraction) indirect effect (expansion) relativistic nonrelativistic Relativistic Effects M.Kaupp, Spektrum der Wissenschaften, 2005 P. Pyykkö

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

Metal Surface

Quartz Surface T dep. Tl, Po, Pb, Bi ≥ 500 K

The EPIPHANIOMETER 219 Rn 211 Pb for 211 Pb (via 211 Bi) (Teflon) No 211 Pb detected for clean gas (no aerosol particles) H.W. Gäggeler et al., J. Aerosol Sci., 20, 557 (1989)

Application to atmospheric aerosol detection at exotic sites

Window/ Target ( 242,244 Pu) Beam ( 48 Ca) Beam stop SiO 2 -Filter Ta metal 850°C Quartz column Cryo On-line Detector (4  COLD) Carrier gas He/Ar (70/30) Teflon capillary (32 pairs PIN diodes, one side gold covered) Hg Loop Temperature gradient: 35°C to – 180 °C T l Rn The element 112,114 experiments (IVO Technique) 112,114? Recoil chamber Quartz inlay

MeV 279 Ds  : s SF MeV MeV 279 Ds  : s SF 112+ n.d. MeV MeV 279 Ds  : s SF MeV MeV 279 Ds  : s SF MeV MeV 279 Ds  : s SF MeV Observed in Chemistry: s 9.54 MeV s MeV 279 Ds 0.18 s SF(>90%) 205 MeV Reported at FLNR: Oganessian et al ms 10.7 MeV The E112 experiments in 2006/ Pu ( 48 Ca, 3n) Ca during eff. 32 days (8 weeks absolute) N R =0.05 N R <1E-5

Results Monte Carlo simulation for one single component Experiment(-5°C) (-21°C) (-21°C) (-39°C) (-124°C) (-28°C) gas flow Courtesy: R. Eichler kJ/mol

Trend of sublimation enthalpy within group 12

Production of E Pu ( 48 Ca, 3n) s SF s 9.95 MeV s 9.54 MeV s MeV 279 Ds 0.2 s SF s 9.16 MeV s 9.82 MeV 281 Ds 11 s SF 244 Pu ( 48 Ca, 3-4n) Yu.Ts. Oganessian et al., 2004

Standard enthalpies of gaseous monoatomic elements Atomic number  H ° 298 [kcal/mol] B. Eichler, 1974

 s  MeV 279 Ds  : s SF  : 0.11 s SF 62+n.d MeV  : 0.10 s SF 108+n.d MeV 242 Pu ( 48 Ca, 3n) Pu ( 48 Ca, 3-4n) MeV Ds  : 3.38 s SF Ca during 51 days Ca during 16 days N R =1.8E-3 N R =1.1E-2 N R =2E-2 N R =1.5E-3 Results with element 114 Dubna 2007 Det#4 Det#

gold ice -88°C -90°C -93°C -4°C Results (2007/2008) Z=112

114 Exp(2007/2008) B. Eichler 2003 R. Eichler et al V.Pershina et al 2008 Prediction and exp. result Dubna 2007/2008 Strong stabilization of elemental 6d 10 7s 2 7p 1/2 2 atomic state!

How to interpret low adsorption enthalpy of E114? Unexpected observation: E114 significantly different to Pb and even more volatile than E112.

Calculated van der Waals energies using covalent radii 1, polarizabilities 2 and ionisation potentials 2 1 P.Pyykkö, M. Atsumi, Chem.Eur. J., 2009, 15, E=114: C. Thierfelder, B. Assadollahzadeh, P. Schwerdtfeger, S. Schäfer, R. Schäfer, Phys. Rev. A 78, (2008) E=112: V.Pershina, A. Borschevsky, E. Eliav, U. Kaldor, J. Chem. Phys. 128, (2008) E112 on Au: -30 kJ/Mol; exp.: -52 kJ/Mol E114 on Au: -23 kJ/Mol; exp.: -34 kJ/Mol (Rn on Au: - 24 kJ/Mol; exp.: -27 kJ/Mol) Courtesy: R. Eichler

Conclusion - On-line gas phase chemistry has reached the sensitivity of about 1 pb - Month-long beam times at highest possible beam intensities mandatory for chemical studies - Single atom chemistry yields reliable chemical information - Elements 112 and 114 surprisingly volatile - Next: element 113 (eka-Tl). Expected volatility of At. - Far future: chemistry from actually s-range to ms-range? (e.g. Stern-Gerlach experiment for atomic electronic configuration) [Proposal E.K. Hulet]

Acknowledgement - Excerpt for Z=112/114 studies - PSI team: R. Eichler et al. FLNR chemistry: S. Dmitriev, S. Shishkin FLNR GNS team: V.K. Utyonkov et al. FLNR VASSILISSA team: A.V. Yeremin et al. FLNR support: Yu. Ts. Oganessian LLNR target: K.J.Moody et al.

E112calc kJ/mol Adsorption of E112 on Au Eichler, R. et al. Nature 487, 72 (2007) Result can be used to improve the prediction models B. Eichler 1985 B. Eichler 2003 V. Pershina et al. 2005/08 R. Eichler et al. 2002