CERN, August 2008. HAPPY LANDING ON THE ISLAND OF SUPERHEAVY ELEMENTS Heinz W. Gäggeler Paul...

CERN, August 2008

CERN, August 2008

HAPPY LANDING ON THE ISLAND OF SUPERHEAVY ELEMENTS

Heinz W. GäggelerPaul Scherrer Institut and

Bern University, Switzerland

Laboratory for Radiochemistry and Environmental Chemistry

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)

CERN, August 2008

Shell stabilisation

Courtesy: S. Hofmann

deformed

spherical

CERN, August 2008Courtesy: M. Schädel

The Dubna claims using 48Ca induced fusion reactions with actinides targets

Periodic Table of the 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

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

CERN, August 2008

Reactions used and number of atoms found in the „first ever chemical studies“ during 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, 3262 (2008))

Element 114: Main experiment at FLNR/JINR; ongoing. Currently evidence for 4 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

Example: Chemical study of bohrium

Example: Chemical study of elements 112 and 114

CsClaerosolsreaction

oven

118MeV 22Ne

22Ne 249Bk FUSION 271Bh* 267Bh

249BkHCl O2

He

chromatographycolumn

Ar

to detection systemROMA

carbon aerosols

reactionproducts

OOn-n-LLine ine GGasaschromatography chromatography AApparatuspparatus

Continuous on-line chemistryContinuous on-line chemistryExample: bohriumExample: bohrium

How to detect single atoms?Textbook example: Discoveryof element 112

SHIP9.2.1996

22:37

SHIP9.2.1996

22:37

277112

11.45 MeV11.45 MeV280 280 ss

11

273110

11.08 MeV11.08 MeV110 110 ss

22

269Hs

9.23 MeV9.23 MeV19.7 s19.7 s

33

265Sg

4.60 MeV (escape)4.60 MeV (escape)7.4 s7.4 s

44

261Rf

8.52 MeV8.52 MeV4.7 s4.7 s

55

257No

8.34 MeV8.34 MeV15.0 s15.0 s

66

70Zn + 208Pb → 277112 + 1n

FirstFirst chemi chemicalcal ccharaharaccteriterization ofzation of bbohriumohrium (Z=107) (Z=107)

T isothermal (°C)

-20 0 20 40 60 80 100 120 140 160 180 200 220

Rel

ativ

e y

ield

(%

)

0

20

40

60

80

100

120

140

160 TcO3Cl 108

(T1/2 = 5.2 s)

Ha = -51 kJ/mol

(T1/2 = 16 s) ReO Cl3

169

Ha = -62 kJ/mol

BhO3Cl 267

(T1/2 = 17 s)

= -75+9-6 kJ/molHa

0 atoms2 atoms

4 atoms

R. Eichler et al., Nature, 407, 63 (2000)

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

CERN, August 2008

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

their macroscopic sublimation enthalpytheir 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

CERN, August 2008CERN, August 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 b) Residence time in collection chamber and transport 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 2007: 3 additional atoms from the 3n channel2007: 3 additional atoms from the 3n channel

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 isotope)

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)

CERN, August 2008

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

CERN, August 2008

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

CERN, August 2008

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

CERN, August 2008

Primary relativistic Primary relativistic effect:effect:

s s p p1/21/2

pp3/23/2 d d3/23/2

dd5/25/2 f f5/25/2

ff7/27/2

m= 1/2 m=-1/2m= 1/2 m=-1/2

m= 3/2 m= 1/2 m= -1/2 m= -3/2m= 3/2 m= 1/2 m= -1/2 m= -3/2

m= 5/2 m= 3/2 m= 1/2 m= -1/2 m= -3/2 m= -5/2m= 5/2 m= 3/2 m= 1/2 m= -1/2 m= -3/2 m= -5/2

m= 7/2 m= 5/2 m= 3/2 m= 1/2 m= -1/2 m= -3/2 m= -5/2 m= -7/2m= 7/2 m= 5/2 m= 3/2 m= 1/2 m= -1/2 m= -3/2 m= -5/2 m= -7/2 White 1931

CERN, August 2008

Secondary Secondary relativistic effect:relativistic effect:

s s p p1/21/2

pp3/23/2 d d3/23/2

dd5/25/2 f f5/25/2

ff7/27/2

m= 3/2 m= 1/2 m= -1/2 m= -3/2m= 3/2 m= 1/2 m= -1/2 m= -3/2

m= 5/2 m= 3/2 m= 1/2 m= -1/2 m= -3/2 m= -5/2m= 5/2 m= 3/2 m= 1/2 m= -1/2 m= -3/2 m= -5/2

m= 7/2 m= 5/2 m= 3/2 m= 1/2 m= -1/2 m= -3/2 m= -5/2 m= -7/2m= 7/2 m= 5/2 m= 3/2 m= 1/2 m= -1/2 m= -3/2 m= -5/2 m= -7/2

White 1931

Spin-OrbitSpin-Orbit splittingsplitting

m= 1/2 m=-1/2m= 1/2 m=-1/2

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

Experiment April/May 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 (thin target & 35% sep.yield)- 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; 2008)=2.7s) (FLNR; 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 a physisorptive van der Waals interaction (similar to a noble gas).

Preliminary!


ConclusionConclusion

Chemical studies at the few atom level Chemical studies at the few atom level have been sucessfully conducted up to Z have been sucessfully conducted up to Z = 114 = 114

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

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.


AcknowledgementAcknowledgement

Yuri Oganessian, Sergei Dmitriev and Yuri Oganessian, Sergei Dmitriev and Georgi GulbekianGeorgi Gulbekian

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

CERN, August 2008. HAPPY LANDING ON THE ISLAND OF SUPERHEAVY ELEMENTS Heinz W. Gäggeler Paul...

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