Deleng sumberé Darmstadtium

{{Elementbox_header | number=110 | symbol=Ds | name=darmstadtium | left=[[meitnerium]] | right=[[roentgenium]] | above=[[platinum|Pt]] | below=(Uhn) | color1=#ffc0c0 | color2=black }}
{{Elementbox_series | [[transition metal]]s }}
{{Elementbox_groupperiodblock | group=10 | period=7 | block=d }}
{{Elementbox_appearance | unknown, probably silvery<br />white or metallic gray }}
{{Elementbox_atomicmass_gpm | [281] }}
{{Elementbox_econfig | perhaps &#91;[[radon|Rn]]&#93; 5f<sup>14</sup> 6d<sup>9</sup> 7s<sup>1</sup><br />(in analogy to [[platinum]]) }}
{{Elementbox_epershell | 2, 8, 18, 32, 32, 17, 1 }}
{{Elementbox_phase | presumably a [[solid]] }}
{{Elementbox_cas_number | 54083-77-1 }}
{{Elementbox_isotopes_begin | color1=#ffc0c0 | color2=black }}
{{Elementbox_isotopes_decay | mn=281 | sym=Ds | na=[[synthetic radioisotope|syn]] | hl=11 s | dm=SF | de= | pn= | ps= }}
{{Elementbox_isotopes_decay2 | mn=279| sym=Ds | na=[[synthetic radioisotope|syn]] | hl=0.20 s | dm1=10% α | de1=9.70 | pn1=275 | ps1=Hs | dm2=90% SF | de2= | pn2= | ps2=}}
{{Elementbox_isotopes_decay | mn=273| sym=Ds | na=[[synthetic radioisotope|syn]] | hl=170 ms | dm=[[alpha emission|α]] | de=11.14 | pn=269 | ps=Hs}}
{{Elementbox_isotopes_decay | mn=271m| sym=Ds | na=[[synthetic radioisotope|syn]] | hl=69 ms | dm=α | de=10.71 | pn=267 | ps=Hs}}
{{Elementbox_isotopes_decay | mn=271g| sym=Ds | na=[[synthetic radioisotope|syn]] | hl=1.63 ms | dm=α | de=10.74,10.69 | pn=267 | ps=Hs}}
{{Elementbox_isotopes_decay | mn=270m| sym=Ds | na=[[synthetic radioisotope|syn]] | hl=6 ms | dm=α | de=12.15,11.15,10.95 | pn=266 | ps=Hs}}
{{Elementbox_isotopes_decay | mn=270g| sym=Ds | na=[[synthetic radioisotope|syn]] | hl=0.10 ms | dm=α | de=11.03 | pn=266 | ps=Hs}}
{{Elementbox_isotopes_decay | mn=269| sym=Ds | na=[[synthetic radioisotope|syn]] | hl=0.17 ms | dm=α | de=11.11 | pn=265 | ps=Hs}}
{{Elementbox_isotopes_decay | mn=267| sym=Ds ?| na=[[synthetic radioisotope|syn]] | hl=0.004 ms | dm= | de= | pn= | ps=}}
{{Elementbox_isotopes_end}}
{{Elementbox_footer | color1=#ffc0c0 | color2=black }}

'''Darmstadtium''' ({{pronEng|dɑrmˈʃtætiəm}}), biyèn dikenal kanthi jeneng Ununnilium, iku sawijining [[unsur kimia]] kanthi simbul '''Ds''' lan [[nomer atom]] 110.

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This [[synthetic element]] is one of the so-called [[super-heavy atom]]s. It decays quickly: Heavier [[isotopes of darmstadtium]] have half-lives on the order of ten seconds.

==Official discovery==
Darmstadtium was [[discovery of the chemical elements|first created]] on November 9, [[1994]] at the [[Gesellschaft für Schwerionenforschung]] (GSI) in [[Wixhausen]], a northern suburb of [[Darmstadt]], [[Germany]] by [[Peter Armbruster]] and [[Gottfried Münzenberg]], under the direction of professor Sigurd Hofmann. Four [[atom]]s of it were detected by a [[nuclear fusion]] reaction caused by bombarding a lead-208 target with nickel-62 ions:
<ref name=95Ho01>[http://www.springerlink.com/content/j51g8342h311x460/ "Production and decay of <sup>269</sup>110"], '''Hofmann et al.''', ''Z. Phys. A.'', 1995, 350, 4. Retrieved on [[2008-03-02]]</ref>

:<math>\,^{208}_{82}\mathrm{Pb} + \,^{62}_{28}\mathrm{Ni} \, \to \,^{269}_{110}\mathrm{Ds} + \; ^1_0\mathrm{n} \; </math>

In the same series of experiments, the same team also carried out the reaction using heavier nickel-64 ions. During two runs, 9 atoms of <sup>271</sup>Ds were convincingly detected by correlation with known daughter decay properties:
<ref name=98Ho01>[http://www.iop.org/EJ/abstract/0034-4885/61/6/002 "New elements-approaching Z=114"], '''S.Hoffman''', ''Rep. Prog. Phys.'',1998, 61, 639-689. Retrieved on [[2008-03-02]]</ref>

:<math>\,^{208}_{82}\mathrm{Pb} + \,^{64}_{28}\mathrm{Ni} \, \to \,^{271}_{110}\mathrm{Ds} + \; ^1_0\mathrm{n} \; </math>

The IUPAC/IUPAP Joint Working Party (JWP) recognised the GSI team as discoverers in their 2001 report.<ref>http://www.iupac.org/publications/pac/2001/pdf/7306x0959.pdf</ref>

==Proposed names==
Element 110 was first given the temporary name ''ununnilium'' ({{IPA|/ˌjuːnəˈnɪliəm/}} or {{IPA|/ˌʌnəˈnɪliəm/}}<ref>[http://dictionary.reference.com/browse/ununnilium]</ref>, symbol '''Uun'''). Once recognized as discoverers, the team at GSI considered the names ''darmstadtium'' (Ds) and ''wixhausium'' (Wi) for element 110. They decided on the former and named the element after the city near the place of its discovery, [[Darmstadt]] and not the suburb [[Wixhausen]] itself. The new name was officially recommended by [[IUPAC]] on [[August 16]], [[2003]].

The element has also earned the nickname of ''policium'', because the telephone number of the police is 110 within Germany.

==Electronic structure==

[[Image:electron shell 110 Darmstadtium.svg|thumb|150px|left]]

Darmstadtium is element 110 in the Periodic Table. The two forms of the projected electronic structure are:

Bohr model: 2, 8, 18, 32, 32, 17, 1

Quantum mechanical model: 1s<sup>2</sup>2s<sup>2</sup>2p<sup>6</sup>3s<sup>2</sup>3p<sup>6</sup>4s<sup>2</sup>3d<sup>10</sup>
4p<sup>6</sup>5s<sup>2</sup>4d<sup>10</sup>5p<sup>6</sup>6s<sup>2</sup>4f<sup>14</sup>5d<sup>10</sup>
6p<sup>6</sup>7s<sup>1</sup>5f<sup>14</sup>6d<sup>9</sup>

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==Extrapolated chemical properties of eka-platinum/dvi-palladium==
===Oxidation states===
Element 110 is projected to be the eighth member of the 6d series of transition metals and the heaviest member of group 10 in the Periodic Table, below [[nickel]], [[palladium]] and [[platinum]].
The highest confirmed oxidation state of +VI is shown by platinum whilst the +IV state is stable for both elements. Both elements also possess a stable +II state. Darmstadtium is therefore predicted to show oxidation states +VI, +IV and +II.

===Chemistry===
High oxidation states are expected to become more stable as the group is descended, so darmstadtium is expected to form a stable hexafluoride, DsF<sub>6</sub>, in addition to DsF<sub>5</sub> and DsF<sub>4</sub>. Halogenation should result in the formation of the tetrahalides, DsCl<sub>4</sub>, DsBr<sub>4</sub> and DsI<sub>4</sub>.

==History of synthesis of isotopes by cold fusion==
===<sup>208</sup>Pb(<sup>64</sup>Ni,xn)<sup>272-x</sup>Ds (x=1)===
This reaction was first studied by scientists at GSI in 1986, without success. A cross section limit  of 12 pb was calculated.
After an upgrade of their facilities, they successfully detected 9 atoms of <sup>271</sup>Ds in two runs in 1994 as part of their discovery experiments on element 110.<ref name=98Ho01/>
This reaction was successfully repeated in 2000 by GSI (4 atoms), in 2000
<ref>[http://prola.aps.org/abstract/PRC/v67/i6/e064609 "Confirmation of production of element 110 by the <sup>208</sup>Pb(<sup>64</sup>Ni,n) reaction"], '''Ginter et al.''', ''Phys. Rev. C'', 67, 064609 (2003). Retrieved on [[2008-03-02]]</ref>
<ref>[http://repositories.cdlib.org/cgi/viewcontent.cgi?article=5446&context=lbnl "Confirmation of production of element 110 by the <sup>208</sup>Pb(<sup>64</sup>Ni,n) reaction"], '''Ginter et al.''', ''LBNL repositories''. Retrieved on [[2008-03-02]]</ref> 
and 2004
<ref>[http://prola.aps.org/abstract/PRL/v93/i21/e212702 "Development of an Odd-Z-Projectile Reaction for Heavy Element Synthesis: <sup>208</sup>Pb(<sup>64</sup>Ni,n)<sup>271</sup>Ds and <sup>208</sup>Pb(<sup>65</sup>Cu,n)<sup>272</sup>111"], '''Folden et al.''', ''Phys. Rev. Lett.'', 93, 212702 (2004). Retrieved on [[2008-03-02]]</ref>
<ref>[http://repositories.cdlib.org/cgi/viewcontent.cgi?article=2704&context=lbnl "Development of an Odd-Z-Projectile Reaction for Heavy Element Synthesis: <sup>208</sup>Pb(<sup>64</sup>Ni,n)<sup>271</sup>Ds and <sup>208</sup>Pb(<sup>65</sup>Cu,n)<sup>272</sup>111"], '''Folden et al.''', ''LBNL repositories''. Retrieved on [[2008-03-02]]</ref> 
by LBNL (9 atoms in total) and in 2002 by [[RIKEN]] (14 atoms).<ref>[http://www.springerlink.com/content/74kn9nq0l28lmlge "Production and decay of the isotope <sup>271</sup>Ds (Z = 110)"], '''Morita et al.''', ''Eur. Phys. J. A.'', 2004, 21, 2. Retrieved on [[2008-03-02]]/</ref> The summation of the data allowed a measurement of the 1n neutron evaporation excitation function.

===<sup>207</sup>Pb(<sup>64</sup>Ni,xn)<sup>271-x</sup>Ds (x=1)===
In addition to the official discovery reactions, in October-November 2000, the team at GSI also studied the reaction using a Pb-207 target in order to search for the new isotope <sup>270</sup>Ds. They succeeded in synthesising 8 atoms of <sup>270</sup>Ds, relating to a ground state isomer, <sup>270g</sup>Ds, and a high-spin K-isomer, <sup>270m</sup>Ds.
<ref>[http://www.dnp.fmph.uniba.sk/etext/68/text/Hofmann_et_al_EPJ_A10_(2001)_5.pdf "The new isotope <sup>270</sup>110 and its decay products <sup>266</sup>Hs and <sup>262</sup>Sg"], '''Hofmann et al'''., ''Eur. Phys. J. A.'', 10, 5-10 (2001). Retrieved on [[2008-03-02]]</ref>

===<sup>208</sup>Pb(<sup>62</sup>Ni,xn)<sup>270-x</sup>Ds (x=1)===
The GSI team studied this reaction in 1994 as part of their discovery experiment. Three atoms of <sup>269</sup>Ds were detected.<ref name=95Ho01/> A fourth decay chain was measured but subsequently retracted.

===<sup>209</sup>Bi(<sup>59</sup>Co,xn)<sup>268-x</sup>Ds===
This reaction was first studied by the team at Dubna in 1986. They were unable to detect any product atoms and measured a cross section limit of 1 pb.
In 1995, the team at LBNL reported that they had succeeded in detecting a single atom of <sup>267</sup>Ds from the 1n neutron evaporation channel. However, several decays were missed and further research is required to confirm this discovery.
<ref>[http://prola.aps.org/abstract/PRC/v51/i5/pR2293_1 "Evidence for the possible synthesis of element 110 produced by the <sup>59</sup>Co+<sup>209</sup>Bi reaction"], '''Ghiorso et al.''', ''Phys. Rev. C'', 51, R2293-R2297 (1995). Retrieved on [[2008-03-02]]</ref>

==History of synthesis of isotopes by hot fusion==
===<sup>232</sup>Th(<sup>48</sup>Ca,xn)<sup>280-x</sup>Ds===
The synthesis of element 110 by hot fusion pathways was first attempted in 1986 by the team at Dubna. Using the method of detection of [[spontaneous fission]], they were unable to measure any SF activities and calculated a cross section limit of 1 pb for the decay mode.
In three separate experiments between November 1997 and October 1998, the same team re-studied this reaction as part of their new <sup>48</sup>Ca program on the synthesis of superheavy elements.
Several SF activities with relatively long half-lives were detected and tentatively assigned to decay of the daughters <sup>269</sup>Sg or <sup>265</sup>Rf, with a cross section of 5 pb. These observations have not been confirmed and the results are taken as only an indication for the synthesis of darmstadtium in this reaction.

===<sup>232</sup>Th(<sup>44</sup>Ca,xn)<sup>276-x</sup>Ds===
This reaction was attempted in 1986 and 1987 by the Dubna team. In both experiments, a 10 ms SF activities was measured and assigned to <sup>272</sup>Ds, with a calculated cross section of 10 pb. This activity is currently not thought to be due to a darmstadtium isotope.

===<sup>238</sup>U(<sup>40</sup>Ar,xn)<sup>278-x</sup>Ds===
This reaction was first attempted by the Dubna team in 1987. Only spontaneous fission from the transfer products <sup>240mf</sup>Am and <sup>242mf</sup>Am were observed and the team calculated a cross section limit of 1.6 pb.
The team at GSI first studied this reaction in 1990. Once again, no atoms of element 110 could be detected. In August 2001, the GSI repeated reaction, without success, and calculated a cross section limit of 1.0 pb.

===<sup>236</sup>U(<sup>40</sup>Ar,xn)<sup>276-x</sup>Ds===
This reaction was first attempted by the Dubna team in 1987. No spontaneous fission was observed.

===<sup>235</sup>U(<sup>40</sup>Ar,xn)<sup>275-x</sup>Ds===
This reaction was first attempted by the Dubna team in 1987. No spontaneous fission was observed.
It was further studied in 1990 by the GSI team. Once again, no atoms were detected and a cross section limit of 21 pb was calculated.

===<sup>233</sup>U(<sup>40</sup>Ar,xn)<sup>273-x</sup>Ds===
This reaction was first studied in 1990 by the GSI team. No atoms were detected and a cross section limit of 21 pb was calculated.

===<sup>244</sup>Pu(<sup>34</sup>S,xn)<sup>278-x</sup>Ds (x=5)===
In September 1994 the team at Dubna detected a single atom of <sup>273</sup>Ds, formed in the 5n neutron evaporation channel. The measured cross section was just 400 fb.
<ref>[http://prola.aps.org/abstract/PRC/v54/i2/p620_1 "α decay of <sup>273</sup>110: Shell closure at N=162"], '''Lazarev et al.''', ''Phys. Rev. C'', 54, 620-625 (1996). Retrieved on [[2008-03-02]] </ref>

==Synthesis of isotopes as decay products==
Isotopes of darmstadtium have also been detected in the decay of heavier elements. Observations to date are shown in the table below:

{| class="wikitable"
|-
! Evaporation Residue
! Observed Ds isotope
|-
| <sup>293</sup>116 , <sup>289</sup>114 
| <sup>281</sup>Ds
|-
| <sup>291</sup>116 , <sup>287</sup>114 , <sup>283</sup>112 
| <sup>279</sup>Ds 
|-
| <sup>277</sup>112 
| <sup>273</sup>Ds
|}

In some experiments, the decay of <sup>293</sup>116 and <sup>289</sup>114 produced an isotope of darmstadtium decaying by emission of an 8.77 MeV alpha particle with a half life of 3.7 minutes. Although unconfirmed, it is highly possible that this activity is associated with a meta-stable isomer, namely <sup>281m</sup>Ds.

==Spectroscopy of darmstadtium isotopes==
===<sup>270</sup>Ds===

[[Image:270Ds decay scheme.png|thumb|325px|none|This is the current partial decay level scheme for <sup>270</sup>Ds proposed following the work of Hofmann et al. in 2000 at GSI]]

==Chronology of isotope discovery==

{| class="wikitable"
|-
! Isotope
! Year discovered
! discovery reaction
|-
| <sup>267</sup>Ds
| 1994?
| <sup>209</sup>Bi(<sup>59</sup>Co,n)
|-
| <sup>268</sup>Ds
| unknown
| 
|-
| <sup>269</sup>Ds
| 1994
| <sup>208</sup>Pb(<sup>62</sup>Ni,n)
|-
| <sup>270</sup>Ds<sup>g,m</sup>
| 2000
| <sup>207</sup>Pb(<sup>64</sup>Ni,n)
|-
| <sup>271</sup>Ds<sup>g,m</sup>
| 1994
| <sup>208</sup>Pb(<sup>64</sup>Ni,n)
|-
| <sup>272</sup>Ds
| unknown
| 
|-
| <sup>273</sup>Ds
| 1996
| <sup>244</sup>Pu(<sup>34</sup>S,5n)
|-
| <sup>274</sup>Ds
| unknown
| 
|-
| <sup>275</sup>Ds
| unknown
| 
|-
| <sup>276</sup>Ds
| unknown
| 
|-
| <sup>277</sup>Ds
| 1997?
| <sup>232</sup>Th(<sup>48</sup>Ca,3n)
|-
| <sup>278</sup>Ds
| unknown
| 
|-
| <sup>279</sup>Ds
| 2002
| <sup>244</sup>Pu(<sup>48</sup>Ca,5n)<ref name=E114ref>see [[ununquadium]]</ref>
|-
| <sup>280</sup>Ds
| unknown
| 
|-
| <sup>281</sup>Ds
| 1999? , 2002
| <sup>244</sup>Pu(<sup>48</sup>Ca,3n)<ref name=E114ref/>
|}

==Chemical yields of isotopes==
===Cold fusion===
The table below provides cross-sections and excitation energies for cold fusion reactions producing darmstadtium isotopes directly. Data in bold represents maxima derived from excitation function measurements. + represents an observed exit channel.

{| class="wikitable"
|-
! Projectile
! Target
! CN
! 1n 
! 2n
! 3n
|-
| <sup>62</sup>Ni
| <sup>208</sup>Pb
| <sup>270</sup>Ds
| 3.5 pb
| 
|
|-
| <sup>64</sup>Ni
| <sup>208</sup>Pb
| <sup>272</sup>Ds
| '''15 pb , 9.9 MeV'''
| 
|
|}

==Isomerism in darmstadtium nuclides==
===<sup>281</sup>Ds===
The production of <sup>281</sup>Ds by the decay of <sup>289</sup>114 or <sup>293</sup>116 has produced two very conflicting decay modes. The most common and readily confirmed mode is SF with a half-life of 11 s. A much rarer and hitherto unconfirmed mode is alpha decay by emission of an 8.77 MeV alpha particle with an observed half-life of ~3.7 m. This decay is associated with a unique decay pathway from the parent nuclides and must be assigned to an isomeric level. The half-life suggests that it must be assigned to a meta-stable state but further research is required to confirm these reports.

===<sup>271</sup>Ds===
Decay data from the direct synthesis of <sup>271</sup>Ds clearly indicates the presence of two alpha groups. The first has alpha lines at 10.74 and 10.69 MeV with a half-life of 1.63 ms. The other has a single alpha line at 10.71 MeV with a half-life of 69 ms. The first has been assigned to the ground state and the latter to an isomeric level. It has been suggested that the closeness of the alpha decay energies indicates that the isomeric level may decay primarily by delayed gamma emission to the ground state, resulting in an identical measured alpha energy and a combined half-life for the two processess.

===<sup>270</sup>Ds===
The direct production of <sup>270</sup>Ds has clearly identified two alpha groups belonging to two isomeric levels. The ground state decays into the ground state of <sup>266</sup>Hs by emitting an 11.03 MeV alpha particle with a half-life of 0.10 ms. The isomeric level decays by alpha emission with alpha lines at 12.15,11.15 and 10.95 MeV with a half-life of 6 ms. The 12.15 MeV has been assigned as decay into the ground state of <sup>266</sup>Hs indicating that this high spin K-isomer lies at 1.12 MeV above the ground state.

==Retracted isotopes==
===<sup>280</sup>Ds===
The first synthesis of [[element 114]] resulted in two atoms assigned to <sup>288</sup>114, decaying to the <sup>280</sup>Ds which underwent [[spontaneous fission]]. The assignment was later changed to <sup>289</sup>114 and hence the darmstadtium isotope to <sup>281</sup>Ds. Hence, <sup>280</sup>Ds is currently unknown.

===<sup>277</sup>Ds===
In the claimed synthesis of <sup>293</sup>118 in 1999, the isotope <sup>277</sup>Ds was identified as decaying by 10.18 MeV alpha emission with a half-life of 3.0 ms. This claim was retracted in 2001 and thus this darmstadtium isotope is currently unknown or unconfirmed.<ref>see [[ununoctium]]</ref>

===<sup>273m</sup>Ds===
In the synthesis of <sup>277</sup>112 in 1996 by GSI (see [[ununbium]]), one decay chain proceeded ''via'' <sup>273</sup>Ds which decayed by emission of a 9.73 MeV alpha particle with a lifetime of 170 ms. This would have been assigned to an isomeric level. This data could not be confirmed and thus this isotope is currently unknown or unconfirmed.

===<sup>272</sup>Ds===
In the first attempt to synthesise element 110, a 10 ms SF activity was assigned to <sup>272</sup>Ds in the reaction <sup>232</sup>Th(<sup>4</sup>4Ca,4n). Given current understanding regarding stability, this isotope has been retracted from the Table of Isotopes.

==References==
{{reflist|2}}

== See also ==
*[[Island of stability]]

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== Pranala njaba ==
{{Commons|Darmstadtium}}
* [http://www.webelements.com/webelements/elements/text/Ds/index.html WebElements.com - Darmstadtium]
* [http://www.iupac.org/news/archives/2003/naming110.html IUPAC: Element 110 is named darmstadtium] {{Webarchive|url=https://web.archive.org/web/20031001232857/http://www.iupac.org/news/archives/2003/naming110.html |date=2003-10-01 }}
* [http://www.apsidium.com/elements/110.htm Apsidium - darmstadtium] {{Webarchive|url=https://web.archive.org/web/20041204021530/http://www.apsidium.com/elements/110.htm |date=2004-12-04 }}
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