Search results for "Spectroscopy"
showing 10 items of 10293 documents
The SO2F2 quasi-spherical top: Correspondence between tensorial and Watson's formalisms
2006
Abstract The SO2F2 quasi-spherical top molecule with C2v symmetry is considered as a distorted spherical top deriving from the SO 4 2 − tetrahedral ion. We present here a detailed correspondence between the tensorial formalism using the Td⊃C2v reorientation and the usual Hamiltonian of Watson. We have also performed ab initio calculations in order to determine the centrifugal distorsion constants in the vibrational ground state.
High-spectral-resolution Fabry-Pérot interferometers overcome fundamental limitations of present volcanic gas remote sensing techniques
2023
Remote sensing (RS) of volcanic gases has become a central tool for studying volcanic activity. For instance, ultraviolet (UV) skylight spectroscopy with grating spectrographs (GS) enables SO2 (and, under favourable conditions, BrO) quantification in volcanic plumes from autonomous platforms at safe distances. These measurements can serve volcanic monitoring and they cover all stages of volcanic activity in long measurement time series, which substantially contributes to the refinement of theories on volcanic degassing. Infrared (IR) remote sensing techniques are able to measure further volcanic gases (e.g., HF, HCl, CO2, CO). However, the employed Fourier transform spectrometers (FTSs) are…
Synthesis, Electrochemistry, and Photophysics of Aza-BODIPY Porphyrin Dyes
2016
International audience; The synthesis of dyad and triad aza-BODIPY-porphyrin systems in two steps starting from an aryl-substituted aza-BODIPY chromophore is described. The properties of the resulting aza-BODIPY-porphyrin conjugates have been extensively investigated by means of electrochemistry, spectroelectrochemistry, and absorption/emission spectroscopy. Fluorescence measurements have revealed a dramatic loss of luminescence intensity, mainly due to competitive energy transfer and photoinduced electron transfer involving charge separation followed by recombination.
Study of the thermochromic phase transition in CuMo1−xWxO4 solid solutions at the W L3-edge by resonant X-ray emission spectroscopy
2021
This is the peer reviewed version of the following article: I. Pudza, A. Kalinko, A. Cintins, A. Kuzmin, Acta Mater. 205 (2021) 116581, which has been published in final form at https://www.sciencedirect.com/science/article/abs/pii/S1359645420310181 This article may be used for non-commercial purposes in accordance with Elsevier Terrms and Conditions for Self-Archiving.
Charged supramolecular assemblies of surfactant molecules in gas phase
2016
The aim of this review is to critically analyze recent literature on charged supramolecular assemblies formed by surfactant molecules in gas phase. Apart our specific interest on this research area, the stimuli to undertake the task arise from the widespread theoretical and applicative benefits emerging from a comprehensive view of this topic. In fact, the study of the formation, stability, and physicochemical peculiarities of non-covalent assemblies of surfactant molecules in gas phase allows to unveil interesting aspects such as the role of attractive, repulsive, and steric intermolecular interactions as driving force of supramolecular organization in absence of interactions with surround…
Synthesis and biological evaluation of novel peptidomimetics as rhodesain inhibitors
2016
Novel rhodesain inhibitors were developed by combining an enantiomerically pure 3-bromoisoxazoline warhead with a 1,4-benzodiazepine scaffold as specific recognition moiety. All compounds were proven to inhibit rhodesain with Ki values in the low-micromolar range. Their activity towards rhodesain was found to be coupled to an in vitro antitrypanosomal activity, with IC50 values ranging from the mid-micromolar to a low-micromolar value for the most active rhodesain inhibitor (R,S,S)-3. All compounds showed a good selectivity against the target enzyme since all of them were proven to be poor inhibitors of human cathepsin L. Novel rhodesain inhibitors were developed by combining an enantiomeri…
Structures and EPR spectra of binary sulfur−nitrogen radicals from DFT calculations
2007
he scattered electron paramagnetic resonance (EPR) spectroscopic data for binary sulfur–nitrogen (S,N) radicals have been compiled and critically assessed.Many of these are inorganic rings or cages.For each species, possible equilibrium structures in the gas phase and the EPR hyperfine coupling (hfc) constants have been calculated with DFT using the B3LYP functional and basis sets of triple-ζ (or better) quality.Good agreement is obtained between calculated and measured values for the well characterized [S3N2]+radical dot, a planar π-radical for which the s-component of the orbitals is likely to be reasonably independent of minor geometrical changes between gas-phase and condensed-phase sta…
Time-gated Raman and laser-induced breakdown spectroscopy in mapping of eudialyte and catapleiite
2020
Raman analysis of rock samples containing rare earth elements (REEs) is challenging due to the strong fluorescence, which may mask the weaker Raman signal. In this research, time‐gated (TG) Raman has been applied to the construction of the mineral distribution map from REE‐bearing rock. With TG Raman, material is excited with a short subnanosecond laser pulse, and the Raman signal is collected within a picosecond‐scale time window prior to the formation of a strong fluorescent signal by means of single‐photon avalanche diode array. This allows signal readout with a significantly reduced fluorescence background. TG Raman maps are used to reveal the location of valuable minerals and are compa…
Co-crystals of an agrochemical active – A pyridine-amine synthon for a thioamide group
2011
Five novel co-crystals of thiophanate-ethyl (TE), an agrochemical active, with di(2-pyridyl)ketone (1), 2-benzoylpyridine (2), 3-benzoylpyridine (3), 4-phenylpyridine (4) and biphenyl (5) were found and crystal structures of four of them (TE1–TE3, TE5) solved by single crystal X-ray diffraction. Three of the co-crystals (TE1–TE3) form by way of a reliable pyridine-amine hydrogen bond synthon and one (TE5) because of close packing effects. The fifth co-crystal was identified by X-ray powder diffraction. The work demonstrates the usage of a reliable supramolecular synthon for crystal engineering, while concurrently reminds that the close packing of even very similar molecules cannot be fully …
MbCo in Saccharide Solid Amorphous Systems: A Combined FTIR and SAXS Study
2011
Saccharides, and in particular trehalose, are known for their efficiency in protecting biostructures against environmental stress [1], although the preservation mechanism is still debated. Experiments and simulations [2,3] on carboxy-myoglobin (MbCO) showed that the protein dynamics is highly inhibited in dry trehalose matrices, the inhibition being dependent on the water content. In these conditions, a mutual protein-matrix structural and dynamic influence is observed.Here we report a combined FTIR and SAXS study on MbCO embedded in dry amorphous matrices of trehalose and sucrose. FTIR measurements were performed at different protein/sugar ratios, focussing on the stretching band of the bo…