<p> </p> <p>  Mass spectrometry (MS) plays an important role in nanomaterials research by facilitating the discovery of superatomic clusters and fullerenes, enabling the identification of atomically substituted clusters, and contributing to understanding mechanisms of cluster formation. In this dissertation, we used different mass spectrometry methods as well as ion soft-landing to address some of the ongoing challenges in cluster science. The first challenge is to extend the atom-by-atom substitution method, which is a promising strategy for designing new cluster-based materials, to a wider range of molecular clusters. Due to challenges associated with the synthesis, purification, and crystallization, this approach has been achieved only for a handful of gold and silver clusters. We extended this approach to enable the substitution of the first-row transitional metals into the core of Co6S8(PEt3)6 cluster, a well-defined metal chalcogenide superatomic cluster and a popular building block for designing novel 2D materials. This cluster is widely used in energy and electronic applications and is an excellent model system for computational studies of cluster-based materials. High-resolution MS analysis identified the formation of Co5MS8(PEt3)6+ (M=Mn, Fe, Ni) clusters, indicating that only Mn, Fe, and Ni atoms can be incorporated into the Co6S8 core using our synthetic method. A combination of mass spectrometric analysis and theoretical studies reaved that each heteroatom has different impact on the relative stability, core-ligand interaction, as well as optical, magnetic, and electrochemical properties of the cluster. </p> <p>Another challenge in the cluster science addressed in this work is the controlled activation of fully ligated clusters by ligand removal. Conventional activation methods such as thermolysis or chemical treatment do not provide sufficient control of the number of the removed ligands and often suffer from sintering of NCs as a result of excessive ligand removal and degradation of the destabilized NC cores. Using a specially-designed ion soft-landing instrument, we achieved a controlled removal of one or two phosphine ligands form the synthesized cobalt sulfide clusters using collision-induced dissociation (CID). The resulting fragments were mass selected and soft-landed onto surfaces. We found out that the reactivity of the fragment ions on surfaces may be controlled by altering the composition of the cluster core and ligand binding energy to the cluster. Although some of the fragments formed by removing one ligand including Co5FeS8(PEt3)5+ and Co6S8L(PPh3)5+ remain unreactive on surfaces, other fragments including Co6S8(PEt3)5+, Co5NiS8(PEt3)5+, and Co6S8(PEt3-xPhx) (x=1-2) undergo selective dimerization.  We observe that the reactivity of fragment ions produced by removing one surface ligand is controlled by the relative stability of the corresponding precursor ions towards fragmentation. In particular, fragment ions generated from more stable precursors undergo a selective dimerization reaction. In contrast, fragment ions produced from the least stable precursors remain largely unreactive on surfaces. In addition, we found that fragments generated by removing two surface ligands are highly reactive and undergo several nonselective reactions. This study demonstrates that fragment ions are unique building blocks that may undergo selective reactivity on surfaces to generate compounds that are difficult to prepare using conventional synthetic methods. We believe that the controlled preparation of fragment ions using ion soft-landing is a generalizable method to activate wide range of ligated nanoclusters which opens a direction for materials design and innovation.</p> <p>Finally, soft-landing of well-characterized redox-active polyatomic anions, PW12O403- (WPOM), was carried out to explore the distribution of pure mass selected anions on semiconducting vertically-aligned TiO2 nanotubes, which were used as a model system for 3D semiconductive materials. Energy dispersive X-ray (EDX) mapping analysis revealed that WPOMs form micron-size aggregates on top of the TiO2 NT and only penetrates 1-1.3 µm into the 10 µm-long nanotubes. This aggregation is attributed to the high resistance of TiO2. This is different from what we see on conductive substrates such as carbon nanotubes (CNTs) where a uniform distribution of ions is typically observed. This study provides valuable insight into the functionalization of porous semiconducting surfaces using mass selected ions for applications in energy storage and electronics.</p>

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The painting Seated lady writing has undergone a technical investigation where its material characteristics were unveiled using non-invasive analytical techniques employing different wavelengths of the spectrum. The panel was analyzed from a material and a visual culture perspective. The thesis aimed to answer what the panel has undergone through time, how its materiality relate to its function, and where and when it was created. In addition, the aim was to investigate the objects portrayed and their value within the artwork’s historical cultural context. The panel show diverse damages that might relate to insect activity, carving with a sharp tool in the face area, stabilization methods evident from remnants of a removed cradling and a possible dimensional reduction. Preparatory features including both free hand underdrawing for minor details, and a tracing technique used for the initial rendering of the female figure and some of the textiles were identified. A blend of meticulously rendered detailing with areas of lesser quality in terms of execution together with the use of common pigments, point to an overall aim of producing art in anefficient way. Later interventions are evident such as the turquoise overpaint on the dress covering the original authentic violet or burgundy color. Visible in X-ray, a dense element covering the bust may be interpreted as a painted thin fabric. The lack of the superficial viscous modelling layers reduce the face of its plasticity and many colors have altered and darkened. The setting and the woman’s fashion indicates an early Dutch 16th century courtly aesthetic. The objects in the rich interior alludes to religious symbolism referring to the Magdalene. The paintings attribution to the Master of the Female Half-Lengths was made in the early 20th century according to the panel’s stereotypical motif, despite the stylistic differences of the figure types. The panel differs from the other attributed panels in thesetting, where the woman seems contemplating in front of a diary, whereas the other women areportrayed writing, playing music or reading. This master has been regarded as synonymous with a workshop production, painting for the blooming 16th century art market in Flemish cities such as Antwerp. This thesis proposes that the paintings ought to be understood in the context of a genre The Female Half-Lengths, as opposed to adhering to one and the same attributed master.