DESIREEDESIREE

DDoubleouble

EElectro-lectro-

SStatictatic

IIonon

RRinging

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Albanova Albanova Instrumentation Instrumentation

SeminarSeminar

2003-10-302003-10-30

HenningHenningSchmidtSchmidt

Timeline:• 1997: First electrostatic ion storage ring ELISA at Århus University

• 1999: Application to NFR for single ring(Larsson, Cederquist, Schmidt) - Not granted.

• 2001: Application to VR for Double-Ring DESIREE (Skeppstedt, Rensfelt, Danared). Outcome: funding for Design Study.

• October 2002: Design Report submitted to VR.Decision postponed due to the uncertain future of MSL.

• June 2003: VR decision to cease funding of MSL

• October 2003: DESIREE gets funding from Wallenberg and VR

• Soon: All the questions of who, where, and when finds their answers and, the design is finished and construction commences.

• 2005 or thereabouts: Inauguration party!

Outline• The DESIREE project

– Motivation: Mutual Neutralization– Technical description– Planned experiments

• AMO Physics– Examples:

Mutual NeutralizationInterstellar Ion Chemistry

• Biomolecules– Example: ‘Electron Capture Dissociation’

• Summary

Plasma environments:Plasma environments:• The degree of ionization is a determining The degree of ionization is a determining

factor for the ongoing chemistry. factor for the ongoing chemistry. Processes that affect this parameter are Processes that affect this parameter are therefore crucial.therefore crucial.

• Electron-Ion recombination:Electron-Ion recombination:– XX+ + + e+ e- - X + h X + h (atomic recombination) (atomic recombination)

ABAB+ + + e+ e- - A + B (dissociative recombination) A + B (dissociative recombination)

• Mutual Neutralization :Mutual Neutralization :– XX++ + Y + Y-- X + Y X + Y

AA-- + BC + BC++ A + BC or A + B + C or ... A + BC or A + B + C or ...

DESIREEDESIREEDDouble ouble EElectro-lectro-SStatic tatic IIon on RRing ing EExpxpEErimentriment

1 m

• Double-walled vacuum vesselDouble-walled vacuum vessel– Outer tank 300K - Inner tank 15KOuter tank 300K - Inner tank 15K

– Cooling by cryogeneratorsCooling by cryogenerators

• Expected vacuum in inner partExpected vacuum in inner part– 300 K: <10300 K: <10-11-11 mbar mbar

– 15 K: Density reduced by order(s) of 15 K: Density reduced by order(s) of magnitudemagnitude

Ion sources:Plasma Ion SourcesSputter Source (Negative Ions)ESI Source (Biomolecules)ECRIS (Highly Charged Ions)+ new ideas….

ELISAELISA

Mutual Neutralization AnimationMutual Neutralization Animation

1 m

Position-sensitive detector

DESIREE

ELISA

Merging / de-merging

tan = 0.02 (corresponds to 4 eV transverse on 10 keV beam)

Merged-beams experiments

• Longitudinally: Kinematical compression

• Transversely: Ion optics determines: < 1 eV seems feasible.

• Can beam cooling be developed?

Relative velocity definition:

• Example: MN H-+H2+

E=10 keV/amu, Erel=1 eV, Amax=1 cm2,=1.6.10-14cm2 (COB), I+=I-=100 nA, L=80 cm: 44 s-1

• Background rate is similar - The key point is that in MN there are (at least) two neutrals in coincidence!!

• How about experiments with Biomolecules?

Count Rate estimates:

RN: In above example N=4.106. Feasible for ESI with trap

0

5

10

15

20

25

-10 -5 0 5 10

v

E

• Longitudinally: Kinematical compression

Three special features of DESIREE:

• Double-ring structure:– Merged beams positive/negative ion collisions.

• Cryogenic system:– Extremely good vacuum Long storage lifetime.– Internally cold molecular ions.

• Electrostatic confinement:– High mass-to-charge ratios (i.e. Biomolecules).– Absence of magnetic-field mixing in lifetime

measurements

• Atoms and ‘Small’ Molecules:– Single-Ring Experiments

• Lifetime measurements of metastable ions (He-, C60q+,…)

• LASER spectroscopy and lifetime measurements– Atomic ions (Continuation of CRYRING project, Mannervik)

– Molecular ions (e.g. Cn-)

– Merged-Beams Experiments• Mutual Neutralization Collisions

– Fundamental systems (e.g. H-+H2+ … DR below 0 eV)

– Astrophysical plasmas (e.g. Cn-+H3

+, H3O+,….)

Examples of proposed experiments at the DESIREE

facility:• Atoms and ‘Small’ Molecules:

– Single-Ring Experiments• Lifetime measurements of metastable ions (He-, C60

q+,…)

• LASER spectroscopy and lifetime measurements– Atomic ions (Continuation of CRYRING project, Mannervik)

– Molecular ions (e.g. Cn-)

– Merged-Beams Experiments• Mutual Neutralization Collisions

– Fundamental systems (e.g. H-+H2+ … DR below 0 eV)

Astrophysics and DESIREE

• Diffuse interstellar clouds:

• Star formation and ion chemistry.– Formation of polyatomic

molecules

– (e.g. H2+ + H2 H3

+ + H)

Two processes limit positive ion abundance:Dissociative Recombination (AB+ + e- A + B)Mutual Neutralization (X+ + Y- X + Y)

Are there any negative ions in the interstellar medium?

’The negative charges may reside more in the form of anions than electrons and mutual neutralization may replace dissociative recombination as the main mechanism for removing positive ions.” Proc. of the 1999 conf on Dissociative Recombination, eds M. Larsson, J.B.A. Mitchell and I.F. Schneider (2000)

Astrophysics and DESIREE

• Old puzzle: Diffuse interstellar absorption bands.– Recent interesting candidates are carbon chain anions:

Cn- (n=6,7,8,9) Tulej et al, Astrophys. J, 506, L69 (1998)

• Alexander Dalgarno, 1999:Cn

- + H2+

H3+

H3O+

CH5+

etc...

• Atoms and ‘Small’ Molecules:– Single-Ring Experiments

• Lifetime measurements of metastable ions (He-, C60q+,…)

• LASER spectroscopy and lifetime measurements– Atomic ions (Continuation of CRYRING project, Mannervik)

– Molecular ions (e.g. Cn-)

– Merged-Beams Experiments• Mutual Neutralization Collisions

– Fundamental systems (e.g. H-+H2+ … DR below 0 eV)

– Astrophysical plasmas (e.g. Cn-+H3

+, H3O+,….)

Examples of proposed experiments at the DESIREE

facility:• Atoms and ‘Small’ Molecules:

– Single-Ring Experiments• Lifetime measurements of metastable ions (He-, C60

q+,…)

• LASER spectroscopy and lifetime measurements– Atomic ions (Continuation of CRYRING project, Mannervik)

– Molecular ions (e.g. Cn-)

– Merged-Beams Experiments• Mutual Neutralization Collisions

– Fundamental systems (e.g. H-+H2+ … DR below 0 eV)

– Astrophysical plasmas (e.g. Cn-+H3

+, H3O+,….)

– Atmospherical ion chemistry.

• Collisions involving fullerenes (C60q++C60

-, Ar8++C60-,….)

Examples of proposed experiments at the DESIREE

facility:• Biomolecules:

– Production, accumulation, conformere selection• The ELISA injector system:

• Biomolecules:– Single-Ring Experiments (already pursued at ELISA)

• Lifetime and stability(J.U.Andersen et al, Eur. Phys. J. D 25, 139 (2003)

• LASER spectroscopy(e.g. GFP: S.B.Nielsen et al PRL 87, 228102 (2001))

• Biomolecules:

Examples of proposed experiments at the DESIREE

facility:

GFP: S.B.Nielsen et al PRL 87, 228102 (2001)

• Biomolecules:– Single-Ring Experiments (already pursued at ELISA)

• Lifetime and stability(J.U.Andersen et al, to be published)

• LASER spectroscopy(e.g. GFP: S.B.Nielsen et al PRL 87, 228102 (2001))

– Merged-Beams Experiments• Electron Capture Dissociation in Negative/Positive ion collisions • Coulombic explosions induced by highly charged ions

• Biomolecules:

Examples of proposed experiments at the DESIREE

facility:• Biomolecules:

– Single-Ring Experiments (already pursued at ELISA)• Lifetime and stability

(J.U.Andersen et al, to be published)

• LASER spectroscopy(e.g. GFP: S.B.Nielsen et al PRL 87, 228102 (2001))

Electron Capture Dissociation

• ECD is important in protein sequencing because it breaks other bonds than those accessed in collision-induced dissociation.

• ECD is studied by introducing electrons in the plasma of FT-ICR mass spectrometer. No control of electron impact energy.

• Using simple negative ion to carry the electron, low (even below zero) and well-controlled relative energy is obtained.

Electron-transfer

10 a0

10 a0

Area of impact for ’distant’ collisions.

• Experimental indication of distant collision:– Detection of neutral at

proper time in relation to the arrival of the biomolecule(ar fragments)

Summary:

• DESIREE can be built!

• We can do new AMO physics in single-ring and particularly in merged-beams configuration (Mutual Neutralization)

• Spectroscopy and lifetime measurements for biomolecular ions - ELISA

• ’ECD’ like processes and HCI-biomolecular ion interaction in merged-beams - DESIREE unique

The End!

DESIREE People:

• Main Applicant: Ö. Skeppstedt (MSL)• Design group: (MSL + SU)

K-G Rensfelt, M. Andersson, L. Bagge,H. Danared, J. Jensen, L. Liljeby, H.T. Schmidt, K. Schmidt, A. Simonsson

• Contributors to the Scientific Programme: (SU + ..)H. T. Schmidt, H. Cederquist, T. Hansson,J. Jensen, M. Larsson, S. Mannervik,P. vd Meulen, J. Pettersson. P. Royen,E. Uggerud, R. A. Zubarev

Mutual Neutralization AnimationMutual Neutralization Animation