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DESIREE as a new tool for interstellar ion chemistry
Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
Visa övriga samt affilieringar
2008 (Engelska)Ingår i: International Journal of Astrobiology, ISSN 1473-5504, E-ISSN 1475-3006, Vol. 7, nr 3-4, s. 205-208Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

A novel cryogenic electrostatic storage device consisting of two ion-beam storage rings with a common straight section for studies of interactions between oppositely charged ions at low and well-defined relative velocities is under construction at Stockholm University. Here we consider the prospect of using this new tool to measure cross-sections and rate coefficients for mutual neutralization reactions of importance in interstellar ion chemistry in general and specifically in cosmic pre-biotic ion chemistry.

Ort, förlag, år, upplaga, sidor
2008. Vol. 7, nr 3-4, s. 205-208
Nationell ämneskategori
Fysik
Forskningsämne
fysik
Identifikatorer
URN: urn:nbn:se:su:diva-32615DOI: 10.1017/S1473550408004229ISI: 000273383100003OAI: oai:DiVA.org:su-32615DiVA, id: diva2:281118
Tillgänglig från: 2009-12-15 Skapad: 2009-12-14 Senast uppdaterad: 2017-12-12Bibliografiskt granskad
Ingår i avhandling
1. Ions in cold electrostatic storage devices
Öppna denna publikation i ny flik eller fönster >>Ions in cold electrostatic storage devices
2010 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

We have constructed a compact purely electrostatic ion-beam trap, ConeTrap, which we have mounted inside a double-walled vacuum chamber. In the inner vacuum chamber, we can obtain ultra-high vacuum (UHV) conditions and reach thermal equilibrium at well controlled temperatures down to 10 K. The chamber was constructed partly with the purpose of making high-precision measurements in ConeTrap, but also as a test-chamber for testing components (such as the detector-assembly tested and described in this thesis and paper III) to be used in the DESIREE (Double ElectroStatic Ion Ring ExpEriment) facility. The latter is a double electrostatic ion storage-ring being constructed at Stockholm University, in which the conditions are meant to mimic the environment in the interstellar medium. The interaction between two oppositely charged ions at very low relative velocities (controlled collision energies down to 10 meV) may then be studied in a section of the storage device where the two ion beams merge.

The lifetime of loosely bound electronic systems, for example He-, is, at room temperature (and even at much lower temperatures), significantly affected by photons from blackbody radiation from the experimental device and its surroundings. The cryogenic temperature and low pressure obtained in the test chamber have made it possible to use ConeTrap to make the first correction-free lifetime measurement of the long-lived J=5/2 fine-structure level of the metastable 1s2s2p 4Po state of He-. Under the assumption of a statistical population of the fine-structure levels, at the time when the ions are created, we have also deduced the lifetimes of the short-lived J=1/2 and J=3/2 fine-structure levels. Furthermore, we have used ConeTrap to measure the pressure dependent storage lifetimes of He+ and Ar+ ions over wide ranges of temperatures and pressures, and we have thus been able to store positive ions with storage lifetimes of tens of seconds.

Ort, förlag, år, upplaga, sidor
Stockholm: Department of Physics, Stockholm University, 2010. s. 89
Nationell ämneskategori
Atom- och molekylfysik och optik
Forskningsämne
fysik
Identifikatorer
urn:nbn:se:su:diva-32659 (URN)978-91-7155-983-8 (ISBN)
Disputation
2010-01-29, FA32, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 10:00 (Engelska)
Opponent
Handledare
Anmärkning
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Tillgänglig från: 2010-01-07 Skapad: 2009-12-15 Senast uppdaterad: 2009-12-15Bibliografiskt granskad
2. Fragmentation of Amino Acids and Microsolvated Peptides and Nucleotides using Electrospray Ionization Tandem Mass Spectrometry
Öppna denna publikation i ny flik eller fönster >>Fragmentation of Amino Acids and Microsolvated Peptides and Nucleotides using Electrospray Ionization Tandem Mass Spectrometry
2010 (Engelska)Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

This thesis presents three different series of high energy (keV) collision experiments as well as a brief scientific introduction to the field. In the first series, protonated glycine and leucine were collided with carbon dioxide and a beam attenuation method was applied to determine their total fragmentation cross sections. A technique was also presented for how to restore the resolution in mass spectra obtained with a hemispherical electrostatic analyzer followed by a position sensitive detector (micro-channel plate equipped with a resistive anode). In the second series of experiments, Collision Induced Dissociation (CID) and Electron Capture Induced Dissociation (ECID) studies were performed on the nucleotide adenosine 5'-monophosphate anion (AMP-) in water complexes.  The two dissociation techniques revealed different fragmentation patterns and a numerical solvent evaporation model was used to interpret the spectra. It was then found that the CID and ECID processes were associated with different internal energy distributions. The third experiment concerned ECID of the protonated dipeptide glycine-alanine ([GA+H]+) in complexes with water, methanol, acetonitrile or crown ether. Depending on the attached molecular species, different ratios between the two competing channels ammonia loss and N-Cα bond cleavage were observed. Quantum chemical calculations revealed that a notable shift in the location of the captured electron occurred for the case of two acetonitriles and one crown ether compared to the bare ion and the ion in complexes with either water or methanol. Finally, this thesis will discuss developments of the electrospray ionization platform as well as the new Double ElectroStatic IonRing ExpEriment (DESIREE) facility.

Förlag
s. 80
Nationell ämneskategori
Atom- och molekylfysik och optik
Forskningsämne
fysik
Identifikatorer
urn:nbn:se:su:diva-37202 (URN)
Presentation
2010-02-15, FA31, Albanova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:15 (Engelska)
Opponent
Handledare
Tillgänglig från: 2011-02-18 Skapad: 2010-02-17 Senast uppdaterad: 2011-02-18Bibliografiskt granskad
3. Probing biomolecular fragmentation
Öppna denna publikation i ny flik eller fönster >>Probing biomolecular fragmentation
2011 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

This thesis deals with fragmentation of complex molecular ions, especially biomolecules, in gas phase collision experiments. The aim is to investigate the relations between energy deposition and fragmentation and to shed light on the mechanisms behind energy and charge transfer processes in collisions involving the building blocks of life. Further, the question how a solvent environment influences the dissociation behavior is elucidated. In the first part of the thesis, results from different collision experiments with biomolecular ions are presented, focusing on electron capture induced dissociation of hydrated nucleotides and small peptides. The investigated processes may be relevant for the understanding of radiation damage and the optimization of sequencing methods used in protein research. Our results clearly demonstrate that effects due to surrounding solvent molecules are substantial. While the dissipation of internal energy by evaporation of the loosely bound solvent molecules may protect the biomolecule, the influence which this environment has on the electronic structure may lead to an enhancement or suppression of certain dissociation channels. The second part of the thesis focuses on recent instrumental developments. Here, the aim was to optimize and complement the techniques used in the experiments above and to have versatile tools available for different kinds of gas phase collision studies involving complex molecular ions. Therefore, we have constructed an electrospray ion source platform for the preparation of intense beams, with options of accumulation and cooling of mass selected ions, allowing for a large variety of experiments. This device is also intended to serve as an ion source for the new storage ring facility DESIREE (DoubleElectroStatic Ion Ring ExpEriment), which is currently under construction at Stockholm University. In these unique storage rings, oppositely charged ions may interact at very low relative velocities in a cryogenically cooled and ultrahigh vacuum environment.

Ort, förlag, år, upplaga, sidor
Stockholm: Department of Physics, Stockholm University, 2011. s. 124
Nationell ämneskategori
Fysik
Forskningsämne
fysik
Identifikatorer
urn:nbn:se:su:diva-54524 (URN)978-91-7447-228-8 (ISBN)
Disputation
2011-03-11, FB55, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2011-02-17 Skapad: 2011-02-04 Senast uppdaterad: 2011-02-07Bibliografiskt granskad

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Av författaren/redaktören
Schmidt, HenningJohansson, HenrikThomas, RichardGeppert, WolfHaag, NicoleReinhed, PeterRosén, StefanLarsson, MatsDanared, HåkanRensfelt, K.-GLiljeby, LeifBagge, LarsBjörkhage, MikaelBlom, MikaelLöfgren, PatrikKällberg, AndersSimonsson, AnsgarPaál, AndrasZettergren, HenningCederquist, Henrik
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FysikumManne Siegbahn-laboratoriet
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