Laboratory for Radiochemistry and Environmental Chemistry

Trends in heavy ion sciences 24 May, 2008


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


How chemists have reached the island of spherical superheavy elements

Heinz W. GäggelerPaul Scherrer Institut and

Bern University, Switzerland

Laboratory for Radiochemistry and Environmental Chemistry

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?

sea of instability

sea of instability

island of Superheavy

Elements

Number of neutrons

Nu

mb

er

of

pro

ton

s

20

50

82

114

20 82 126 184

peak of Sn

peak of Ca

peak of Pb

peak of U

strait of radioactivity

strait of instability

G.N. Flerov, A.S. Ilyinov (1982)

Trends in heavy ion research, 24 May 2008

Shell stabilisation

Courtesy: S. Hofmann

deformed

spherical

PeriodicPeriodicTable of Table of thethe Elements

DsDs

H

Li

Na

K

Rb

Cs

Fr Ra Ac

Ba

Sr

Ca

Mg

Be

Sc

Y

La

Ti

Zr

Hf

V

Nb

Ta

Cr

Mo

W

Mn

Tc

Re

Fe

Ru

Os

Co Ni Cu Zn Ga Ge As

Rh Pd Ag Cd In Sn Sb

Ir Pt Au Hg Tl Pb Bi

Rf Db Sg

B C N O F

Al Si P S Cl

Se Br

Te I

Po At87 88 89 104 105 106

55 56 57 72 73 74 75 76 77

37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53

78 79 80 81 82 83 84 85

19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

11 12 13 14 15 16 17

3 4

1

5 6 7 8 9

1

2

3 4 5 6 7 8 9 10 11 12

13 14 15 16 17

Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

58

90

59 60 61 62

91 92 93 94

63

95 96 97 98 99 100 101

64 65 66 67 68 69

102 103

70 71

LanthanidesLanthanides

ActinidesActinides

Bh107

Hs

Mt

108

109 110

RgRg111

112

114 116

- -

He

Ne

Ar

Kr

Xe

Rn

54

86

36

18

10

2

18

113113

114

115115

116116

118118

Mendelejev‘s first Periodic Table Mendelejev‘s first Periodic Table from 1871from 1871

Basis for the discovery of several new elements!

H

Li

Na

K

Rb

Cs

Fr Ra Ac

Ba

Sr

Ca

Mg

Be

Sc

Y

La

Ti

Zr

Hf

V

Nb

Ta

Cr

Mo

W

Mn

Tc

Re

Fe

Ru

Os




Rf Db

B C N O F

Al Si P S Cl

Se Br

Te I

Po At87 88 89-103 104 105

55 56 57-71 72 73 74 75 76 77

37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53

78 79 80 81 82 83 84 85

19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

11 12 13 14 15 16 17

3 4

1

5 6 7 8 9

1

2

3 4 5 6 7 8 9 10 11 12

13 14 15 16 17

LanthanideLanthanidess

AAcctinidetinidess

114

- -116

- -

He

Ne

Ar

Kr

Xe

Rn

54

86

36

18

10

2

18



58

90

59 60 61 62

91 92 93 94

63

95 96 97 98 99 100 101

64 65 66 67 68 69

102 103

70 71

La

Ac

57

89

Positioning of new elementsPositioning of new elementsinto the Periodic into the Periodic ttableable

Sg106

Bh107

Hs108

Mt109 110

Ds Rg112

- -

Sg106

20002000

Bh107

Hs108

200220022001 - 20072001 - 20071993 - 19971993 - 1997

112

- -114

- -

≥ 2007

111 113 115 116 118

Trends in heavy ion research, 24 May 2008

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

IIsothermsothermalal CChromatographhromatography: Sg,Bhy: Sg,Bh

Tem

per

atu

re [

°C]

Column length [cm] Temperature [°C]

Yie

ld [

%]

50%TtRet. = T1/2

Gas flow

highlow

TThermochromatographhermochromatography: Hs, Z=112; Z=114y: Hs, Z=112; Z=114

Tem

per

atu

re [

°C]

Column length [cm] Temperature [°C]

Yie

ld [

%]

Ta

high

Gas flow

low

Elements with Z ≥ 112: filled 6d10 shell: 7p-element behaviour (volatile noble metals)

DsDs

H

Li

Na

K

Rb

Cs

Fr Ra Ac

Ba

Sr

Ca

Mg

Be

Sc

Y

La

Ti

Zr

Hf

V

Nb

Ta

Cr

Mo

W

Mn

Tc

Re

Fe

Ru

Os




Rf Db Sg

B C N O F

Al Si P S Cl

Se Br

Te I

Po At87 88 89 104 105 106

55 56 57 72 73 74 75 76 77

37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53

78 79 80 81 82 83 84 85

19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

11 12 13 14 15 16 17

3 4

1

5 6 7 8 9

1

2

3 4 5 6 7 8 9 10 11 12

13 14 15 16 17



58

90

59 60 61 62

91 92 93 94

63

95 96 97 98 99 100 101

64 65 66 67 68 69

102 103

70 71


ActinidesActinides

Bh107

Hs

Mt

108

109 110

RgRg111

112

114 116

- -

He

Ne

Ar

Kr

Xe

Rn

54

86

36

18

10

2

18

113113

114

115115

116116

118118

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

Adsorption of single atoms of mercury and radon on a gold

surface

0

5

10

15

20

25

30

35

40

45

50

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31

lenght [cm]

yiel

d [

%]

0

50

100

150

200

250

300

350

400

450

500

tem

per

atu

re [

K]

192Hg Hads = -87 kJ/mol219Rn Hads = -27 kJ/mol

Adsorption of single atoms of mercury and radon on a quartz surface

0

10

20

30

40

50

60

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 32lenght [cm]

yiel

d [

%]

0

50

100

150

200

250

300

350

400

450

500

tem

per

atu

re [

K]

192Hg Hads = -24.5 kJ/mol219Rn Hads = -20.5 kJ/mol

Trends in heavy ion science, 24 May 2008

Correlation between adsorption properties of single atoms on gold Correlation between adsorption properties of single atoms on gold

and their macroscopic sublimation enthalpyand their macroscopic sublimation enthalpy

Texas A&M, Nov. 2007

DsDs

H

Li

Na

K

Rb

Cs

Fr Ra Ac

Ba

Sr

Ca

Mg

Be

Sc

Y

La

Ti

Zr

Hf

V

Nb

Ta

Cr

Mo

W

Mn

Tc

Re

Fe

Ru

Os




Rf Db Sg

B C N O F

Al Si P S Cl

Se Br

Te I

Po At87 88 89 104 105 106

55 56 57 72 73 74 75 76 77

37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53

78 79 80 81 82 83 84 85

19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

11 12 13 14 15 16 17

3 4

1

5 6 7 8 9

1

2

3 4 5 6 7 8 9 10 11 12

13 14 15 16 17



58

90

59 60 61 62

91 92 93 94

63

95 96 97 98 99 100 101

64 65 66 67 68 69

102 103

70 71


ActinidesActinides

Bh107

Hs

Mt

108

109 110

RgRg111

112

114 116

- -

He

Ne

Ar

Kr

Xe

Rn

54

86

36

18

10

2

18

113113

114

115115

116116

118118

Element 112 similar to Hg?

Window/Target (242Pu: 1.4 mg/cm2)

Beam (48Ca; 233-239 MeV)

Beam stop

SiO2-FilterTa metal850°C

Quartz column

Cryo On-line Detector (4Cryo On-line Detector (4 COLD)COLD)

Carrier gas He/Ar (70/30)

Teflon capillary

(32 pairs PIN diodes, one side gold covered)

HgHg Loop

Temperature gradient: 35°C to – 184 °C

T

l

RnRn

The element 112 experimentThe element 112 experiment(IVO (IVO [I[In-situ n-situ VVolatilisation andolatilisation and O On-line detectionn-line detection]]

Technique)Technique)

111122Recoil

chamber

Quartz inlay

Trends in heavy ion science, 24 May 2008Trends in heavy ion science, 24 May 2008

Studies on element 112Studies on element 112 242242Pu(Pu(4848Ca;3n)Ca;3n)287287114 (0.5 s) 114 (0.5 s) → 4s → 4s 283283112112 Reasons Reasons

a) High cross section of a) High cross section of 5 pb ( 5 pb ( 3-times higher than 3-times higher than via direct production with via direct production with 238238U as a target)U as a target)

b) Residence time in collection chamber and transport b) Residence time in collection chamber and transport capillary capillary 2 s 2 s 283112

9.54 MeV

4 s

Rf 2614 s

8.5 MeV

Ds 279

0.2 s


10

50

0.1

0.5

Cro

ss s

ecti

on

s / 3

MeV

(re

lati

ve u

nit

s)

1

5

3n2n

3n

2n

4n5n

4n

5n

30 3525Excitation energy (MeV)

40 45 50 55

xn-channel cross sectionsfrom 242,244Pu+48Ca reactions

Excitation functionsExcitation functions

Courtesy: Yu. Oganessian. “Heaviest Nuclei from 48Ca-induced Reactions” TAN-07, Davos, Sept. 23-27, 2007

283112

9.37 MeV

287114

279Ds: 0.592 s

SF108+123 MeV

Observed in Chemistry:Observed in Chemistry:11.05.20062:40 (moscow time)

283112

9.48 MeV

287114

279Ds: 0.536 s

SF127+105 MeV

25.05.20068:37 (moscow time)

Result from the Result from the 4848Ca + Ca + 242242Pu experimentPu experiment

Laboratory for Radiochemistry and Environmental Chemistry

Three week bombardment with 3.1x1018 48Ca ions at 236 ± 3 MeV

First independent confirmation of 283112 formation and decay properties! (R. Eichler et al., Nature, 447, 72 (2007))

283112

9.35 MeV

287114

279Ds: 0.773 s

SF85+12 MeV

Result from additional Result from additional 4848Ca + Ca + 242242Pu experiments in Pu experiments in 20072007

Bombardment 21.3.- 17.4. 2007 with 3.1x1018 48Ca ions at 237± 3 MeV

283112

9.52 MeV

287114

279Ds: 0.072 s

SF112 + n.d MeV

283112

9.52 MeV

287114

279Ds: 0.088 s

SF94+51 MeV

The chemistry experiment is not sensitive to the 4n channel (too short-lived nuclides)

The chemistry of element 112The chemistry of element 112

Element 112 is similar to Hg, but slightly more volatile

Deduced adsorption enthalpy: -52-52+20+20-4-4 kJ/mol (black solid line) kJ/mol (black solid line)


The chemistry of element 112The chemistry of element 112

HHsublsubl=39=39+23+23-10 -10 kJ/mol (68% c.i.)kJ/mol (68% c.i.)

-52-52+20+20-4-4 kJ/mol kJ/mol


Trend of sublimation enthalpy within group 12Trend of sublimation enthalpy within group 12


What‘s next?

• 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

from: V. Pershina et al., J. Chem. Phys., 127, 134310 (2007)

Group 14:

6d107s27p2

Prediction by Pitzer (1975)

Is element 114 a noble gas due to a strong spin-orbit splitting of the 7p orbitals?


Studies on element 114Studies on element 114 Reaction: Reaction: 242242Pu(Pu(4848Ca;3n)Ca;3n)287287114 (T114 (T1/21/2 =0.5s) =0.5s)

(FLNR; spring 2007)(FLNR; spring 2007)

Rf 2614 s

8.5 MeV

Ds 279

0.24s

283112

287114

10.9 s

9.54 MeV

10.0 MeV1 atom on Au at – 80 °C

3.1x1018 48Ca ions at 237± 3 MeV

unpublished


Studies on element 114Studies on element 114 Reaction: Reaction: 244244Pu(Pu(4848Ca;4n)Ca;4n)288288114 (T114 (T1/21/2 =0.8s) =0.8s)

Rf 2614 s

8.5 MeV

2 atoms on Au at –10 °C & -84 °C

Beam dose 4x10Beam dose 4x101818

Energy within targets: Energy within targets: 243 – 231 MeV243 – 231 MeV((~ 1.4 mg/cm~ 1.4 mg/cm22))

288114 288114

9.95 MeV 9.81 MeV

284112 284112

0.11 s 0.11 s

unpublished

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

dwittwer

1.Klick:Radonquelle: nach 1.5 s kommt das Atom2.Klick:Ca-48 Strahl: Radon geht weg3.Klick:Transfer Produkte4.Klick:Einzelnes "114": Läuft nur einmal5.Klick:Thermochromaographie mit Carrier Gas6.Klick:114 in der Thermochromatographie, mit Zerfall

Pro & Contra

• Pro:- Extremely clean - spectra (no background)- no sf-contamination by sputtered target

• Contra:- Lower efficiency- Smaller energy range in the thin target


Studies on element 114Studies on element 114

Reaction: Reaction: 244244Pu(Pu(4848Ca;3n)Ca;3n)289289114 (T114 (T1/21/2 =2.7s) (FLNR; =2.7s) (FLNR; ongoingongoing 2008) 2008)

Rf 2614 s

8.5 MeV

281Ds

3.3s

285112

289114

9.12 MeV

Not detected

1 atom on Au at – 97 °C

4x1018 48Ca ions at E* = 38 – 42 MeV

SF 106+50

unpublished

-200

-150

-100

-50

0

50

-200

-150

-100

-50

0

50

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 320

2

4

6

8

10

Hads

Au=-35 kJ/mol

288114

Detector #

icegold

0

2

4

6

8

10 ice

Pu-244

Rel

. yi

eld

/ de

tect

or,

%Pu-242 gold

Tem

per

atur

e, °

C

287114

Hads

Au=-35 kJ/mol

Decay during transport?

Prelim

inary

unpublished

0 50 100 150 200 2500

50

100

150

200

250 experimantal data least square fit: 95% c.i.

-Hads

(Au) = (1.08±0.05)*Hsubl

+(10.3±6.4), kJ/mol

-H

ads(A

u), k

J/m

ol

Hsubl

, kJ/mol

At

Hg

RnXe

Kr

Tl

Bi

PbPo

E114

Prelim

inary

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).


ConclusionConclusion Chemical research on heaviest elements has Chemical research on heaviest elements has

been much boosted by the recent discoveries of been much boosted by the recent discoveries of many new nuclides up to Z=118 at FLNR many new nuclides up to Z=118 at FLNR

Chemical studies at the few atom level have Chemical studies at the few atom level have been sucessfully conducted up to Z = 112 been sucessfully conducted up to Z = 112

Elements Bh, Hs & 112 (as well as Rf, Db, Sg) Elements Bh, Hs & 112 (as well as Rf, Db, Sg) behave in gas phase studies as expected from behave in gas phase studies as expected from extrapolations within the groups of the periodic extrapolations within the groups of the periodic tabletable

Ongoing studies point to an element 114 Ongoing studies point to an element 114 behaviour unlike that of eka-Pb, but rather behaviour unlike that of eka-Pb, but rather similar to a noble gas. similar to a noble gas.


Many thanksMany thanks

To Yuri Oganessian for his constant To Yuri Oganessian for his constant support and very active engagement support and very active engagement in the experimentsin the experiments

To Sergei Dmitriev and his team for To Sergei Dmitriev and his team for the Dubna chemiststhe Dubna chemists

To Georgi Gulbekian and his team for To Georgi Gulbekian and his team for the excellent the excellent 4848Ca beamsCa beams

To Robert Eichler and his team from To Robert Eichler and his team from the PSI/Univ. Bern collaborationthe PSI/Univ. Bern collaboration

Raw data from few-hour measurement with pre-separation (GNS) (left) and without (right)

219Rn 215Po

212Po214Po211At

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