CERN, August 2008. HAPPY LANDING ON THE ISLAND OF SUPERHEAVY ELEMENTS Heinz W. Gäggeler Paul...
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Transcript of CERN, August 2008. HAPPY LANDING ON THE ISLAND OF SUPERHEAVY ELEMENTS Heinz W. Gäggeler Paul...
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 insta- bility
G.N. Flerov, A.S. Ilyinov (1982)
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
Co Ni Cu Zn Ga Ge As
Rh Pd Ag Cd In Sn Sb
Ir Pt Au Hg Tl Pb Bi
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
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
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
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
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
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
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
CERN, August 2008CERN, August 2008
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?
CERN, August 2008CERN, August 2008
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
CERN, August 2008CERN, August 2008
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
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
CERN, August 2008CERN, August 2008
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!
CERN, August 2008CERN, August 2008
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.
CERN, August 2008CERN, August 2008
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