Publikationer
Organization of Nanoparticles in Solution-A TEM Study
Avdelning/ar:
Publiceringsår: 2004
Språk: Engelska
Sidor: 106
Dokumenttyp: Doktorsavhandling
Förlag: Materials Chemistry, Kemicentrum, Lund University, P.O. Box 124, S-22100 Lund, Sweden,
Övrig information: Article: I. Novel, spongelike ruthenium particles of controllable size stabilized by organic solvents, O. Vidoni, K. Philippot, C. Amiens, B. Chaudret, O. Balmes, J. O. Malm, J. O. Bovin, F. Senocq, M. J. Casanove; Angew. Chem. Int. Ed. 1999, 38, 24, 3736.
Article: II. A new view on chemistry of solids in solution-cryo energy filtered transmission electron microscopy (cryo-EFTEM) imaging of aggregating palladium colloids in vitreous ice, J. O. Bovin, T. Huber, O. Balmes, J. O. Malm, G. Karlsson; Chem. Eur. J. 2000, 6, 1, 129.
Article: III. Platinum colloids stabilized by bifunctional ligands: self-organization and connection to gold, S. Gomez, L. Erades, K. Philippot, B. Chaudret, V. Colliere, O. Balmes, J. O. Bovin; Chem Comm. 2001, 1474-1475.
Article: IV. Cryo-TEM observation of 3-dimensionally ordered aggregates of 5-nm gold particles in organic solvents. O. Balmes, J. O. Malm, G. Karlsson, J. O. Bovin. Submitted to Journal of Nanoparticle Research
Article: V. Self-Healing, Self-Organized Gold Nanoparticle Films at a Water/Organic Solvent Interface. O. Balmes, J. O. Bovin, J. O. Malm. Submitted to Applied Nanoscience
Article: VI. Imaging atomic-structure in metal nanoparticles using high resolution cryo-TEM. O. Balmes, J.-O. Malm, N. Petterson, G. Karlsson, J.-O. Bovin. Manuscript
Sammanfattning
Nanoteknologi är en ung vetenskap där man sysslar med strukturer som är större än molekyler men mindre än ett tusendels hårstrå. Förklaringen till att nanoteknologi etablerats som ett nytt begrepp finner sin grund i att vid dessa dimensioner beter sig material på sätt som varken kan beskrivas rent kemiskt eller är lika bulkegenskaper. Nya egenskaper gör entré.
Det sätts stort hopp till att man ska kunna utnyttja dessa egenskaper till nya eller förbättrade maskiner, datorer, medicinska ändamål, osv. För detta krävs att man får bättre kontroll över syntes och manipulering av sådana små strukturer.
I detta arbete har ett modellsystem av små strukturer syntetiseras och studerats med hjälp av elektronmikroskopi. Dessa system består av metallpartiklar i varierande storlek, men alla i nanometerskala. Genom att använda en speciell provprepareringsteknik har det varit möjligt att studera dessa strukturer i vätskefas, vilket inte har gjorts tidigare. Tack vare detta har man observerat att ordnade strukturer av 5 nanometer stora partiklar förekommer redan i lösning. Ordnade aggregat har observerats i organiska lösningsmedel samt ordnade monolager vid gränsskiktet mellan vattenfas och oljefas.
Med hjälp av dessa partiklar har man också kunnat bevisa den hittills bästa publicerade upplösningen i ett fryst prov. Detta resultat bevisar prestandan hos ett av de nyligen installerade elektronmikroskopen vid det Nationella Centrumet för Högupplösande Elektronmikroskopi (nCHREM) i Lund.
Det sätts stort hopp till att man ska kunna utnyttja dessa egenskaper till nya eller förbättrade maskiner, datorer, medicinska ändamål, osv. För detta krävs att man får bättre kontroll över syntes och manipulering av sådana små strukturer.
I detta arbete har ett modellsystem av små strukturer syntetiseras och studerats med hjälp av elektronmikroskopi. Dessa system består av metallpartiklar i varierande storlek, men alla i nanometerskala. Genom att använda en speciell provprepareringsteknik har det varit möjligt att studera dessa strukturer i vätskefas, vilket inte har gjorts tidigare. Tack vare detta har man observerat att ordnade strukturer av 5 nanometer stora partiklar förekommer redan i lösning. Ordnade aggregat har observerats i organiska lösningsmedel samt ordnade monolager vid gränsskiktet mellan vattenfas och oljefas.
Med hjälp av dessa partiklar har man också kunnat bevisa den hittills bästa publicerade upplösningen i ett fryst prov. Detta resultat bevisar prestandan hos ett av de nyligen installerade elektronmikroskopen vid det Nationella Centrumet för Högupplösande Elektronmikroskopi (nCHREM) i Lund.
A new approach to the study of nanoparticle systems has been introduced.
Nanoparticle systems in aqueous and organic solutions have been synthesized and studied by transmission electron microscopy. These systems include nanoparticles of gold, silver, palladium, ruthenium, and platinum which have been stabilized using various ligands. The particles were initially studied as deposited samples on carbon film by traditional transmission electron microscopy. It was observed that this type of sample preparation introduces artifacts due to the hydrodynamic effects in the solvent and interactions with the substrate upon drying.
A specific sample preparation method, plunge-freezing, was used in order to produce samples representative of the state of aggregation of the particles in solution. This sample preparation, which was previously mainly used on aqueous samples, has been adapted to organic solvent-based samples. Differences in electron beam sensitivity were noted between different solvents.
Observation of nanoparticle systems with this method allowed evidencing the presence of ordered aggregates of particles already in solution. These structures appear to be equilibrium structures. One specific ligand allowed the formation of interfacial films of nanoparticles between an aqueous phase and an organic phase. Using the plunge freezing technique, these films could be determined to be organized monolayers of particles, with some defects present.
The compatibility of this technique with energy-filtered imaging was demonstrated on bimetallic systems. High resolution capability of this technique was also demonstrated by recording images with structural resolution of better than 2 Ångström.
Nanoparticle systems in aqueous and organic solutions have been synthesized and studied by transmission electron microscopy. These systems include nanoparticles of gold, silver, palladium, ruthenium, and platinum which have been stabilized using various ligands. The particles were initially studied as deposited samples on carbon film by traditional transmission electron microscopy. It was observed that this type of sample preparation introduces artifacts due to the hydrodynamic effects in the solvent and interactions with the substrate upon drying.
A specific sample preparation method, plunge-freezing, was used in order to produce samples representative of the state of aggregation of the particles in solution. This sample preparation, which was previously mainly used on aqueous samples, has been adapted to organic solvent-based samples. Differences in electron beam sensitivity were noted between different solvents.
Observation of nanoparticle systems with this method allowed evidencing the presence of ordered aggregates of particles already in solution. These structures appear to be equilibrium structures. One specific ligand allowed the formation of interfacial films of nanoparticles between an aqueous phase and an organic phase. Using the plunge freezing technique, these films could be determined to be organized monolayers of particles, with some defects present.
The compatibility of this technique with energy-filtered imaging was demonstrated on bimetallic systems. High resolution capability of this technique was also demonstrated by recording images with structural resolution of better than 2 Ångström.
Disputation
2004-06-11
13:15
Room C, Kemicentrum, Lund Institute of Technology.
- Wolfgang Meyer-Zaika (Dr)
Nyckelord
- Technology and Engineering
- Materiallära
- materialteknik
- Material technology
- organisation
- plunge freezing
- TEM
- nanoparticle
- transmission electron microscopy
Övrigt
- ISBN: 91-628-6123-9
