Matilda: a mass filtered nanocluster source

dc.contributorTurner, C. Heath
dc.contributorWeaver, Mark Lovell
dc.contributorMankey, Gary J.
dc.contributorLane, Alan M.
dc.contributor.advisorKlein, Tonya M.
dc.contributor.authorKwon, GiHan
dc.contributor.otherUniversity of Alabama Tuscaloosa
dc.date.accessioned2017-02-28T22:21:14Z
dc.date.available2017-02-28T22:21:14Z
dc.date.issued2009
dc.descriptionElectronic Thesis or Dissertationen_US
dc.description.abstractCluster science provides a good model system for the study of the size dependence of electronic properties, chemical reactivity, as well as magnetic properties of materials. One of the main interests in cluster science is the nanoscale understanding of chemical reactions and selectivity in catalysis. Therefore, a new cluster system was constructed to study catalysts for applications in renewable energy. Matilda, a nanocluster source, consists of a cluster source and a Retarding Field Analyzer (RFA). A moveable AJA A310 Series 1"-diameter magnetron sputtering gun enclosed in a water cooled aggregation tube served as the cluster source. A silver coin was used for the sputtering target. The sputtering pressure in the aggregation tube was controlled, ranging from 0.07 to 1torr, using a mass flow controller. The mean cluster size was found to be a function of relative partial pressure (He/Ar), sputtering power, and aggregation length. The kinetic energy distribution of ionized clusters was measured with the RFA. The maximum ion energy distribution was 2.9 eV/atom at a zero pressure ratio. At high Ar flow rates, the mean cluster size was 20 ~ 80nm, and at a 9.5 partial pressure ratio, the mean cluster size was reduced to 1.6nm. Our results showed that the He gas pressure can be optimized to reduce the cluster size variations. Results from SIMION, which is an electron optics simulation package, supported the basic function of an RFA, a three-element lens and the magnetic sector mass filter. These simulated results agreed with experimental data. For the size selection experiment, the channeltron electron multiplier collected ionized cluster signal at different positions during Ag deposition on a TEM grid for four and half hours. The cluster signal was high at the position for neutral clusters, which was not bent by a magnetic field, and the signal decreased rapidly far away from the neutral cluster region. For cluster separation according to mass to charge ratio in a magnetic sector mass filter, the ion energy of the cluster and its distribution must be precisely controlled by acceleration or deceleration. To verify the size separation, a high resolution microscope was required. Matilda provided narrow particle sized distribution from atomic scale to 4nm in size with different pressure ratio without additional mass filter. It is very economical way to produce relatively narrow particle size distribution.en_US
dc.format.extent121 p.
dc.format.mediumelectronic
dc.format.mimetypeapplication/pdf
dc.identifier.otheru0015_0000001_0000101
dc.identifier.otherKwon_alatus_0004D_10056
dc.identifier.urihttps://ir.ua.edu/handle/123456789/608
dc.languageEnglish
dc.language.isoen_US
dc.publisherUniversity of Alabama Libraries
dc.relation.hasversionborn digital
dc.relation.ispartofThe University of Alabama Electronic Theses and Dissertations
dc.rightsAll rights reserved by the author unless otherwise indicated.en_US
dc.subjectChemical engineering
dc.subjectPhysics, Optics
dc.titleMatilda: a mass filtered nanocluster sourceen_US
dc.typethesis
dc.typetext
etdms.degree.departmentUniversity of Alabama. Department of Chemical and Biological Engineering
etdms.degree.disciplineChemical & Biological Engineering
etdms.degree.grantorThe University of Alabama
etdms.degree.leveldoctoral
etdms.degree.namePh.D.
Files
Original bundle
Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
file_1.pdf
Size:
8.09 MB
Format:
Adobe Portable Document Format