1 / 15


Belfast, July 1, 2003. A3: DESIREE. ( D ouble E lectro S tatic I on R ing E xp E riment). Design and examples of planned experiments. Henning Schmidt, Stockholm University. Stockholm Low-Energy facilities:. DESIREE Double ElectroStatic Ion Ring ExpEriment .

Download Presentation


An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.


Presentation Transcript

  1. Belfast, July 1, 2003 A3: DESIREE (Double ElectroStatic Ion Ring ExpEriment) Designand examples of planned experiments Henning Schmidt, Stockholm University

  2. Stockholm Low-Energy facilities: • DESIREEDouble ElectroStatic Ion Ring ExpEriment. • CRYSIS (EBIS source for very high charge states e.g. U70+) • ECR ion source for intense beams of moderately high charge states.

  3. Outline • The DESIREE project • Motivation: Mutual Neutralization • Brief technical description • Planned experiments • AMO Physics • Example: Diffuse interstellar absorption bands • Biomolecules • Example: ‘Electron Capture Dissociation’ • Summary

  4. Plasma environments: • The degree of ionization is a determining factor for the ongoing chemistry. Processes that affect this parameter are therefore crucial. • Electron-Ion recombination: • X+ + e-  X + h (atomic recombination)AB+ + e-  A + B (dissociative recombination) • Mutual Neutralization : • X+ + Y- X + YA- + BC+  A + BC or A + B + C

  5. DESIREE Ion sources: Plasma Ion Sources Sputter Source (Negative Ions) ESI Source (Biomolecules) ECRIS (Highly Charged Ions) Double Electro-Static Ion Ring ExpEriment • Double-walled vacuum vessel • Outer tank 300K - Inner tank 15K • Cooling by cryogenerators • Expected vacuum in inner part • 300 K: <10-11 mbar • 15 K: Density reduced by order(s) of magnitude 1 m

  6. Position-sensitive detector ELISA 1 m DESIREE

  7. Count Rate estimates: Merged-beams experiments • Longitudinally: Kinematical compression • Transversely: Ion optics determines: < 1 eV seems feasible. • Can beam cooling be developed? • 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? RN: In above example N=4.106. Feasible for ESI with trap Relative velocity definition:

  8. 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

  9. Examples of proposed experiments at the DESIREE facility: • Atoms and ‘Small’ Molecules: • Single-Ring Experiments • Lifetime measurements of metastable ions (He-, C60q+,…) • LASER spectroscopy of atomic/molecular ions (e.g. Cn-) • Merged-Beams Experiments • Mutual Neutralization Collisions • Fundamental systems (e.g. H-+H2+ …..) • Astrophysical plasmas (e.g. Cn-+H3+, H3O+,….) • Atmospherical ion chemistry. • Collisions involving fullerenes(C60q++C60-, Ar8++C60-,….)

  10. Examples of proposed experiments at the DESIREE facility: • Biomolecules: • 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)) • 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

  11. 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.

  12. Electron-transfer 10 a0 10 a0

  13. 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)

  14. 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!

  15. DESIREE People: New Life! New Leif? • Primary investigator: Ö. Skeppstedt • Design group: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: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

More Related