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The development of highly ultraviolet (UV) and near-infrared (NIR) absorbent transparent coatings is an important enabling technology and area of research for environmental sustainability and energy conservation. Different amounts of K4[{Nb5TaXi12}Xa6] cluster compounds (X = Cl, Br) dispersed into polyvinylpyrrolidone matrices were prepared by a simple, nontoxic and low-cost wet chemical method. The resulting solutions were used to fabricate visibly transparent, highly UV and NIR absorbent coatings by drop casting. The properties of the solution and films were investigated by complementary techniques (optical absorption, electrospray ionization mass spectrometry and Raman spectroscopy). The UV and NIR absorption of such samples strongly depended on the concentration, dispersion and oxidation state of the [{Nb5TaXi12}Xa6] nanocluster-based units. By varying and controlling these parameters, a remarkable improvement of the figures of merit TL/TE and SNIR for solar-glazing applications was achieved compared to the previous results on nanocomposite coatings based on metal atom clusters. [ABSTRACT FROM AUTHOR]

Buckmlnsterfullerene ([C.sub.60) as a primary ion for secondary ion mass spectrometry (SIMS) has shown many benefits over classical SIMS sources in the analysis of large organic molecules including many of biological significance. One constraint has been the limited focusing capabilities of the [C.sub.60] beam. Although this could be circumvented by using beam size limiting apertures at the cost of beam current, high-resolution imaging using conventional time-of-flight (TOF) instruments has been challenging and time-consuming. We present a method in which we combine the use of an unfocused [C.sub.60.sup.+] beam with an ion optical microscope. A delay line detector is used to obtain fully resolved hyperspectral data sets that contain both the full mass spectral and the localization information. The obtained image resolving power is 4[micro]m at a pixel size of 250 nm. Microscope mode [C.sub.60.sup.+] imaging was shown to resolve micrometer-scale features in a combined polymer-tissue sample. Our new approach demonstrates high-quality SIMS imaging using the full [C.sub.60.sup.+] beam current. This results in equal or better resolving power at reduced acquisition speed. 10.1021/ac902587g

The antagonism between global energy needs and the obligation to slow global warming is a current challenge. In order to ensure sufficient thermal comfort, the automotive, housing and agricultural building sectors are major energy consumers. Solar control materials and more particularly, selective glazing are part of the solutions proposed to reduce global energy consumption and tackle global warming. In this context, these works are focused on developing new highly ultraviolet (UV) and near-infrared (NIR) absorbent nanocomposite coatings based on K4[{Nb6-xTaxXi12}Xa6]. (X = Cl, Br, 0 ≤ x ≤ 6) transition metal cluster compounds. These compounds contain cluster-based active species that are characterized by their strong absorption of UV and NIR radiations as well as their good transparency in the visible range, which makes them particularly attractive for window applications. Their integration, by solution processes, into a silica-polyethylene glycol or polyvinylpyrrolidone matrices is discussed. Of particular interest is the control and the tuning of their optical properties during the integration and shaping processes. The properties of the solutions and films were investigated by complementary techniques (UV-Vis-NIR spectrometry, ESI-MS, SEM, HRTEM, etc.). Results of these works have led to the development of versatile solar control coatings whose optical properties are competitive with commercialized material. [ABSTRACT FROM AUTHOR]

A study presents infrared spectra of the protonated monomers of glycine, alanine, valine and leucine methyl esters. These protonated species were generated in the gas phase through matrix aided laser desorption ionization (MALDI) within the cell of a Fourier transform ion cyclotron resonance spectrometer (FTICR) where they are then mass selected as the only species trapped in the FTICR cell.

The distance-dependence of excitation energy transfer, e.g., being described by Förster theory (Förster resonance energy transfer (FRET)), allows the use of optical techniques for the direct observation of structural properties. Recently, this technique has been successfully applied in the gas phase. The detailed interpretation of the experimental FRET results, however, relies on the comparison with structural modeling. We therefore present a complete first-principles modeling approach that explores the gas-phase structure of chromophore-grafted peptides and achieves accurate predictions of FRET efficiencies. We apply the approach to amyloid-ß 12-28 fragments, known to be involved in amyloid plaque formation connected to Alzheimer's disease. We sample structures of the peptides that are grafted with 5-carboxyrhodamine 575 (Rh575) and QSY-7 chromophores by means of replicaexchange molecular dynamics simulations upon an Amber-type forcefield parametrization as a function of the charge state. The generated ensembles provide chromophore-distance and -orientation distributions which are used with the spectral parameters of the Rh575/QSY-7 chromophores to model FRET-efficiencies for the systems. The theoretical values agree with the experimental average "action"-FRET efficiencies and motivate to use the herein reported parametrization, sampling, and FRET-modeling technique in future studies on the structural properties and aggregation-behavior of related systems. [ABSTRACT FROM AUTHOR]

The frequency-based gas-phase infrared multiple photon dissociation (IRMPD) spectrum for the proton-bound dimer of water is discussed. The quantum 4D model of Vener et al. can be used to describe the experimental spectrum, although with very different assignments of the modes.

Rationale: Among the sources of structural diversity in biomolecular ions, the co‐existence of protomers is particularly difficult to take into account, which in turn complicates structural interpretation of gas‐phase data. Methods: We investigated the sensitivity of gas‐phase photo‐fragmentation measurements and ion mobility spectrometry (IMS) to the protonation state of a model peptide derivatized with chromophores. Accessible interconversion pathways between the different identified conformers were probed by tandem ion mobility measurement. Furthermore, the excitation coupling between the chromophores has been probed through photo‐fragmentation measurements on mobility‐selected ions. All results were interpreted based on molecular dynamics simulations. Results: We show that protonation can significantly affect the photo‐fragmentation yields. Especially, conformers with very close collision cross sections (CCSs) may display dramatically different photo‐fragmentation yields in relation with different protonation patterns. Conclusions: We show that, even if precise structure assignment based on molecular modeling is in principle difficult for large biomolecular assemblies, the combination of photo‐fragmentation and IMS can help to identify the signature of protomer co‐existence for a population of biomolecular ions in the gas phase. Such spectroscopic data are particularly suitable to follow conformational changes. [ABSTRACT FROM AUTHOR]