Tunable far-infrared-vacuum-ultraviolet two color ionization is used to obtain vibrational spectra of neutral silicon clusters in the gas phase. Upon excitation with tunable infrared light prior to irradiation with UV photons we observe strong enhancements in the mass spectrometric signal of specific cluster sizes. This allowed the recording of the infrared absorption spectra of Si(6), Si(7), a...

We report here a general synthetic strategy to encapsulate metal clusters within zeolites during their hydrothermal crystallization. Precursors to metal clusters are stabilized against their premature colloidal precipitation as hydroxides during zeolite crystallization using bifunctional (3-mercaptopropyl)trimethoxysilane ligands. Mercapto (-SH) groups in these ligands interact with cationic me...

Amorphous silicon is an important material, amidst a debate whether or not it is a glass. We produce amorphous Si surfaces by ion bombardment and vapor growth, and image discrete Si clusters which hop by two-state dynamics at 295 K. Independent of surface preparation, these clusters have an average diameter of ∼5 atoms. Given prior results for metallic glasses, we suggest that this cluster size...

Aerodynamic levitation of a multicomponent 17 wt% Si glass formed by rapid quenching of the melt phase was studied by high resolution x-ray diffraction (XRD) and reverse Monte Carlo (RMC) modelling. The main local atomic order features comprised interactions between Si, Fe and Mg polyhedra, the stereochemistry of which was on a par with the literature. Both the glass and the liquid state appear...

Pre-precipitation clustering and chemical nature of the metastable precipitates in aged Al-Mg-Si(-Cu) alloys have been investigated by atom probe field ion microscopy (APFIM) and transmission electron microscopy (TEM) for better understanding of the two-step aging behavior and the effect of excess Si. After a prolonged natural aging, co-clusters of Mg and Si atoms are observed in addition to se...

Aluminum forms various structures on Si(100)-2×1. The most important of these are one-dimensional chains which are formed at room temperature and Si-Al clusters which can form c(4×12) reconstruction at temperature about 500 °C. STS spectra were measured above Al chains, in its close surroundings and above typical defects which are formed on the chains. One type of defect which appears at temper...

Clustering aims at representing large datasets by a fewer number of prototypes or clusters. It brings simplicity in modeling data and thus plays a central role in the process of knowledge discovery and data mining. Data mining tasks, in these days, require fast and accurate partitioning of huge datasets, which may come with a variety of attributes or features. This, in turn, imposes severe comp...

The dependence of the mechanism of age hardening in Al-Mg-Si alloys on their Si content, the pre-aging conditions and addition of Cu has been investigated. For this purpose, the solute clusters and the metastable precipitates in aged Al-Mg-Si alloys have been characterized by a three dimensional atom probe (3DAP) and transmission electron microscopy (TEM). Atom probe analysis results have revea...

We report a joint experimental and theoretical study on the structures of a series of gold clusters doped with a group-14 atom: MAux (M ) Si, Ge, Sn; x ) 5-8). Well-resolved photoelectron spectra were obtained and compared to calculations at several levels of theory to identify the low-lying structures of MAu5-8. We found that the structure of SiAu5 is dominated by the tetrahedrally coordinated...