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Numerous projects and industrial and academic collaborations benefit from state-of-the-art facilities and expertise in analytical chemistry available at the Swiss Universities of Applied Sciences. This review summarizes areas of expertise in analytical sciences at the University of Applied Sciences and Arts Northwestern Switzerland (FHNW), the University of Applied Sciences and Arts Western Switzerland (HES-SO), and the Zurich University of Applied Sciences (ZHAW). We briefly discuss selected projects in different fields of analytical sciences

The aim of this project was to develop a general concept to assess the laboratory experiments in the instrumental analysis laboratory, at the Institute of Chemistry and Biological Chemistry (ICBC) at the Zurich University of Applied Sciences (ZHAW), in terms of their sustainability and, where possible, to improve the sustainability rating of the laboratory experiments. Hence, the primary objective was to implement an empirical assessment methodology, including the “Sustainability Code” that was composed of four parts and a “Sustainability Load Index”. During the spring semester 2015, 105 different experimental projects were performed in the ICBC’s analytical chemistry practical course. These were carried out on 18 different instrumental workspaces, encompassing 12 different analytical methodologies. For the development of the first and second parts of the Sustainability Code, information concerning the chemical substances (in any state- solid, liquid or gas) used and the energy consumption of the apparatus was recorded. The third and fourth parts contain (approximate) information on the use of consumables and the sustainability of the method with reference to the apparatus used. The Load Index (LI) consists of an aggregation (summary) of the direct causality indicators ‘substances’ and ‘energy’ into a single figure. The experiments were classified on a 3-level Load Index Scale into ‘ideal’ analysis methods (LI> 20), ‘sustainable’ methods of analysis (LI 20-200), and analysis methods ‘with potential for optimization’ (LI

In the past decade, we have witnessed rapid development of direct-injection mass spectrometric (DIMS) technologies that combine ever-improving mass and time resolution with high sensitivity and robustness. Here, we review some of the most significant DIMS technologies, which have been applied to rapid monitoring and quantification of volatile organic compounds (VOCs) and biogenic VOCS (BVOCs). They include MS-e-noses, atmospheric-pressure chemical ionization (APCI), proton-transfer-reaction mass spectrometry (PTR-MS), and selected ion-flow-tube mass spectrometry (SIFT-MS). DIMS-based MS-e-noses provide the possibility to screen large sample sets and may yield rich analytical information. APCI is a widespread ionization method and pioneered DIMS in environmental and flavor-release applications. SIFT-MS and PTR-MS allow better control of precursor-ion generation and hence of the ionization process. SIFT-MS puts the focus on control of the ionization process, while PTR-MS does so on sensitivity. Most (B)VOCs of interest can be efficiently detected and often identified by DIMS, thanks also to the possibility of switching between different precursor ions and the recent realization of time-of-flight-based equipments. Finally, we give selected examples of applications for each of the key technologies, including research in food-quality control (MS-e-nose), flavor release (APCI), environmental sciences (PTR-MS) and health sciences (SIFT-MS).

Mixed metal clusters of sodium and cesium with gold have been generated in a supersonic expansion from the mixed vapor phase. Their tendency towards binary cluster formation, relative thermodynamic stability, and ionization potentials have been experimentally and computationally investigated. The properties of the NaxAu clusters may be understood within an electronic shell model based on delocalized cluster orbitals, whereas the characteristics of CsxAu are indicative of substantial ionic interactions. Relativistic density functional calculations have been performed to elucidate the cluster electronic structure and to rationalize observed properties which may not be accounted for by the jellium model. The properties of these finite-size clusters are shown to be related to the known bulk intermetallic compounds sodium gold and cesium-gold (cesium aurid), respectively.

The preferred fragmentation patterns of negatively charged carbon clusters, C−N have been investigated by cluster—beam impact methods using various surfaces and impact energies (Ei = 0-150 eV). Transitions from one type of cluster structure to another are inferred from the observed change in fragmentation patterns. The results are made possible by the high intact-scattering yield of C−N clusters, and by the competitiveness of fragmentation with electron emission for clusters N < 40. The main inferred structures and diagnostic fragmentation patterns are (i) chain structures (4 < N < 18), which fragment by C(0)3 loss; (ii) ring structures, N ≈ 17-32, reflected by preferential cleavage to give large neutral clusters C(0)14, and C(0)22, (iii) polycyclic or cage structures, which shatter to yield an array of small fragments; and (iv) fullerene-type structures, N > 33, for which electron emission dominates over fragmentation. These results are compared and contrasted with results obtained from other fragmentation and collisional methods.

Die Strukturbildung an Grenzflachen, deren Induktion und Charakterisierung, dadurch bewirkte Fortschritte in der heterogenen Katalyse und die Aufklarung der Struktur elektrochemischer Phasengrenzen sind Schwerpunkte dieses Trendberichts. Von hoher Aktualitat sind auch die zeitaufgeloste Untersuchung chemischer Reaktionen, die Nutzung der Dichtefunktionaltheorie fur neue quantenchemischen Methoden und die Cluster.

An experimental technique is investigated to separate/enrich fullerenes of metallofullerenes, exploiting differences in sublimation temperatures without the use of solvents. Fullerenes are sublimed out of the soot and deposited on a quartz rod along a temperature gradient (gradient sublimation). In a position-sensitive experiment the composition of the deposit on the rod is monitored by laser-desorption mass spectrometry. Strongly enriched regions containing specific fullerene molecules (i.e., C[sub 84] or LaC[sub 82]) are observed. Furthermore, C[sub 74], which could not be extracted from the soot by organic solvents, sublimes out of the soot. 26 refs., 6 figs.

The authors report the formation of fullerenes from graphite by sputtering and electron beam evaporation. Under conditions that differ dramatically from those in the previously known fullerene production processes, the new methods preferentially yield the soluble higher fullerenes C{sub 70}, C{sub 76}, C{sub 78}, and C{sub 84} in addition to minor amounts of C{sub 60} only. Upon passage of carbon particles formed by electron beam evaporation through an electrostatic field, fullerenes are mainly isolated from the cathode, not from the anode, which supports the formation of cationic intermediates in fullerene growth mechanisms. The variables thought to be important for fullerene production can be controlled efficiently in the new processes. 18 refs., 3 figs.

Interest in on-line measurements of volatile organic compounds (VOCs) is increasing, as sensitive, compact, and affordable direct inlet mass spectrometers are becoming available. Proton-transfer reaction mass spectrometry (PTR-MS) distinguishes itself by its high sensitivity (low ppt range), high time resolution (200 ms), little ionization-induced fragmentation, and ionization efficiency independent of the compound to be analyzed. Yet, PTR-MS has a shortcoming. It is a one-dimensional technique that characterizes compounds only via their mass, which is not sufficient for positive identification. Here, we introduce a technical and analytical extension of PTR-MS, which removes this shortcoming, while preserving its salient and unique features. Combining separation of VOCs by gas chromatography (GC) with simultaneous and parallel detection of the GC effluent by PTR-MS and electron impact MS, an unambiguous interpretation of complex PTR-MS spectra becomes feasible. This novel development is discussed on the basis of characteristic performance parameters, such as resolution, linear range, and detection limit. The recently developed drift tube with a reduced reaction volume is crucial to exploit the full potential of the setup. We illustrate the performance of the novel setup by analyzing a complex food system.

The technique of carbon-arc evaporation has been successfully utilized to encapsulate a wide variety of rare-earth species in carbon cages. The authors have observed M{sub m} @ C{sub n} (M = Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, or Er) species present in the toluene extracts of the carbon soot using laser desorption mass spectrometry. The presence of multiple-metal species appears to depend strongly on the metal-to-carbon atom ratio found in the starting rods, with the higher metal concentrations favoring multiple-metal incorporation. One often observed dimetallofullerene is M{sub 2}{degrees}C{sub 80}. Molecular orbital arguments are presented to support a possible icosahedral structure for C{sub 80}. 27 refs., 2 figs., 1 tab.

Density functional studies of the abundant cluster Na6Pb and of its analogue Na6Mg are reported. The structure of Na6Pb has been optimized for a series of symmetry constraints (Oh, D3d, D3h, C5v, C3v and C2v). The resulting binding energies fall within a narrow range of less than 0.1 eV whereas a spread of more than 0.5 eV is calculated for Na6Mg. These findings indicate a high structural flexibility of Na6Pb. The Pb atom exhibits a propensity to occupy a highly coordinated site in contrast to Mg which, in the most stable structures, is attached to the ‘outside’ of a Na6 moiety. Analysis of the bonding mechanism revealed two major contributions which increase the atomization energy of Na6Pb compared to Na6Mg: an enhanced charge transfer from the Na6 subsystem and a stronger polarization of the Pb atom. A significant contribution to the overall cluster stability comes from the interaction between the alkali atoms.

Recently we reported on vibrationally resolved spectra of the ionic ground state of Ag 2 + via ZEKE spectroscopy. The vibronic intensity distributions could not be interpreted within the Franck-Condon scheme. Here, we show that it is possible to overcome this discrepancy by invoking the breakdown of the Born-Oppenheimer approximation in the ZEKE states of silver dimer. A comparison of the spectral structure of the direct ion signal with simultaneously recorded ZEKE band profiles further illustrates this non-Franck-Condon behavior.

Mass-spectral results on alkali clusters containing one host-atom with ns2 valence-shell configuration (Mg, Ca, Sr, Ba, Zn, Eu, and Yb) are presented. They allow uncoupling of the number of atoms in the cluster from the number of its valence electrons by probing with elements with more than one valence electron and different ionization potential and atomic radius. Prominent intensity maxima for specific cluster sizes are observed. Based on an electronic shell model, a systematic interpretation of the intensity maxima as a function of the incorporated heteroatom is presented. Although most of the gross features can be rationalized within a purely electronic model, a more refined analysis prompts one to geometric structure effects which have to be included to more fully describe the spectra.

We report on mass-analyzed ZEKE spectra of Ag+2 via resonance-enhanced two-color excitation. To the best of our knowledge, this is the first metal dimer and at the same time the heaviest system (218 amu) ever investigated by mass-analyzed ZEKE. The adiabatic ionization potential, vibrational energies for v+ = 1, 2, 3 and 4 as well as the vibrational constants ωe, ωeχe of the ionic ground state X2Σ+g are determined with high accuracy. The surprising intensity pattern of vibrational progressions cannot be rationalized within a Franck—Condon picture and points to the unique properties of ZEKE states.

In this article, recent cluster—surface collision experiments are reviewed from the perspective of fullerene research. A detailed description of the method and the reflectron time-of-flight surface collider (reflectron collider), designed and built in Los Angeles, will be given first, to show how pulsed cluster-ion-beams are mass and energy selected, collided with specific surfaces and the various outcomes studied. In the second part, we outline several applications together with the scientific impact surface collision experiments have had on several fullerene-related research subjects. This includes impact-induced dissociation experiments, to probe stability and structural resilience, rebound velocity distributions from solid surfaces to reveal energetic and dynamic aspects of the scattering process, and rates of delayed electron emission from impact-heated fullerenes. Impact experiments also have turned out to be a useful tool to examine structural hypotheses as demonstrated on coalescence products from fullerene—fullerene reactions, fullerene derivatives and on metallo-fullerenes.

Recent experiments have demonstrated that large fullerenes can form by coalescence in the hot and dense vapor produced by pulsed UV-laser desorption of a fullerene film. The abundance spectra exhibit masses both at and close to the primary coalescence product. We suggest a rate equation that reproduces this pattern, applicable to the nearly symmetric abundance distributions observed in coalescence with high laser fluence and also to the strongly asymmetric case of coalescence with low fluence. The equation is parameterized by three rates, which in the completely symmetric and in the completely asymmetric case reduces to two. In these two cases the relative abundances can be expressed by a single dimensionless parameter.

This article reviews recent work in Los Angeles on elementary processes in fullerene vapors. The production of fullerene molecules typically involves extreme high-temperature conditions and processes which are poorly understood at date [1–3]. Once generated, these molecules may represent the most stable molecules known [4,5]. In a recent work [C. Yeretzian et al., Nature 359, 44 (1992)] we presented clear evidence for coalescence reactions between fullerene molecules. Mass spectrometric measurements on hot, dense vapors of small fullerenes (C60 and C70) reveal the formation of stable higher fullerenes which are multiples of the initial masses. These processes are shown to occur in the gas-phase rather than in the solid film and their dependences on laser fluence and He-gas pressure are investigated. Three distinct reactions are proposed—coalescence, emission and capture—to account for the observed distributions at higher fullerene sizes. Specifically, the heat of coalescence is released through emission of small, even-numbered fragments which, in a very dense vapor, are efficiently captured by other coalesced fullerenes. These findings have implications for the long-time stability of the fullerene vapor, and for the mechanism of fullerene formation and growth, and may open new ways to the synthesis of selected higher fullerenes and encapsulation compounds.

The disintegration and coalescence processes of fullerenes have not yet been established, although certain aspects have been known for years. For example, the energy required to fragment C 60 has been calculated to lie in the 11–14 eV range, making it the most stable large molecule known, while reported experimental values are in the 4.5–7 eV range. In this report, we show that surface-impact heating of fullerene-ion beams, when properly calibrated, gives values in agreement with theory. In the last section, new mass spectrometric results on the coalescence reactions of hot fullerene vapors are presented.

The soluble molecule La2C80 recently reported by Alvarez et al. exhibits a robustness similar to other fullerenes. It survives intact for ≈ 10−6s following impact against solid surfaces Si(100) at up to 200 eV, yielding an estimate Ef>4 eV for fragmentation processes. The high threshold for electron emission suggests that the electron affinity in La2C−80 is significantly larger than in C60. These facts seem to rule out an external site for either La atom and disfavor a network-site interpretation, and thus favor endohedral (encapsulation) sites. Among the possible cages, the Ih-C80 fullerene appears to be highly favorable for the oxidation state (La3+)2C6−80.

In this article, a method for high-resolution laser spectroscopy of ions—termed ZEro-Kinetic Energy spectroscopy (ZEKE)— is reviewed. Emphasis will be put on a more recent, mass-selective version (mass-analyzed ZEKE). A detailed description of the apparatus, designed and built at the Technische Universitat Munchen, will first be given. In a second part, we outline two applications which are particularly suited to illustrate the potential of the method. We hope to demonstrate to the mass spectrometry community the close connection between a ZEKE spectrometer and a conventional reflectron time-of-flight mass spectrometer (TOF-MS). Adding one single electrostatic field lens to the extraction field region of a TOF-MS allows to go far beyond mass analysis, distinguishing, for example, between isomeric structures or determining the geometric structure of molecular ions.

Recent mass spectroscopic studies of continuous cluster beams resulting from supersonic expansions of alkali metal vapor have led to the postulation of islands of enhanced thermodynamic stability among the clusters produced. We discuss the various assumptions being made in converting ion abundances measured in these mass spectra into information about neutral stabilities. In this connection a number of experiments are described which allow insight into unimolecular dissociation of alkali cluster ions and into neutral cluster growth.

Controversy regarding the interpretation of photoionization efficiency measurements obtained for alkali clusters provided impetus for higher-resoln. (3.3 nm) studies . The new data cover the full range of cluster sizes: Nax, x

During the course of mass spectral studies on the stability of bimetallic systems, an exceptionally abundant and stable Na6Pb cluster was discovered. For given exptl. conditions, an intense mol. beam consisting exclusively of the particle Na6Pb is generated via self-assembly from a mixed vapor of sodium and lead. While this observation is reminiscent of the discovery of C60 or Tl8C12, Na6Pb represents the first example of a binary finite-size 'alloy' ( 0.5 nm diam.) exhibiting such extraordinary stability. [on SciFinder (R)]