Photoelectron spectroscopy of (CO2)−n clusters with 2≤n≤13: Cluster size dependence of the core molecular ion

1988 ◽  
Vol 88 (9) ◽  
pp. 5857-5863 ◽  
Author(s):  
Michael J. DeLuca ◽  
Baohua Niu ◽  
Mark A. Johnson
Keyword(s):  
Photoelectron Spectroscopy ◽  
Cluster Size ◽  
Size Dependence ◽  
Molecular Ion ◽  
The Core

PHOTOELECTRON SPECTROSCOPY OF ${\rm{Co}}_n^-$ AND PRODUCT ANIONS OF ${\rm{Co}}_n^-$ WITH O2 AND N2

1996 ◽  
Vol 03 (01) ◽  
pp. 667-670 ◽  
Author(s):  
HIROYUKI YOSHIDA ◽  
AKIRA TERASAKI ◽  
TAMOTSU KONDOW
Keyword(s):  
Electronic Structure ◽  
Excimer Laser ◽  
Photoelectron Spectroscopy ◽  
Cluster Size ◽  
Size Dependence ◽  
Size Range ◽  
Photoelectron Spectra ◽  
Electron Affinities ◽  
Cluster Radius ◽  
Xecl Excimer Laser

The photoelectron spectra of [Formula: see text](3≤n≤70), Co m N − and Co m O −(3≤m≤6) were measured by a XeCl excimer laser (4.025 eV). Also the reactivities of [Formula: see text] with O 2 and CO were measured. A clear distinction between the cluster size of n≤6 and that of n≥7 was observed both in the photoelectron spectra and in the reactivities. (i) In the size range above n=7, the electron affinities of the cobalt clusters determined by the photoelectron spectra are linearly dependent on the reciprocal of the cluster radius, but below this size they deviate from this relation. (ii) The reactivity of [Formula: see text] with O 2 in the size range below n=6 is higher than that above n=7. However, the reactivity with CO in the size range below n=6 is extremely lower than that above n=7. These findings suggest that a transition of electronic structure in size dependence, which is correlated with the reactivity, occurs at n≃7.

STUDY OF IRON–CARBON MIXED CLUSTERS FeCn (n=2−5): A POSSIBLE LINEAR-TO-CYCLIC TRANSITION FROM FeC3 TO FeC4

1996 ◽  
Vol 03 (01) ◽  
pp. 423-427 ◽  
Author(s):  
LAI-SHENG WANG
Keyword(s):  
Photoelectron Spectroscopy ◽  
Cluster Size ◽  
Structural Transition ◽  
Carbon Clusters ◽  
Cyclic Structure ◽  
Cyclic Transition ◽  
Pure Carbon ◽  
Cyclic Isomer ◽  
Anion Photoelectron Spectroscopy ◽  
Mixed Clusters

Small Fe/C mixed clusters, [Formula: see text], are studied by anion photoelectron spectroscopy at 3.49-eV photon energy. The spectra of [Formula: see text] and [Formula: see text] show well-resolved features and are consistent with linear-to-linear detachment transitions. The [Formula: see text] spectrum is quite broad, suggesting large geometry change from the anion to the neutral. Since [Formula: see text] is known to be linear, our data suggest that neutral FeC4 may have a cyclic structure. The spectrum of [Formula: see text] exhibits both sharp and broad features, consistent with the existence of both a linear and a cyclic isomer. A linear-to-cyclic structural transition is thus suggested to take place for the neutral FeCn clusters from n=3−4; for n<4 they are linear and for n≥4 they can be both linear and cyclic. This is similar to the linear-to-cyclic transition occurring for pure carbon clusters from n=9−10 (Ref. 10) but at a much smaller cluster size due to the presence of the Fe atom.

Theoretical core spectroscopy of molecules interacting with ice surfaces 

2021 ◽  
Author(s):  
Richard Asamoah Opoku
Keyword(s):  
Electronic Properties ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Trace Gases ◽  
Binding Energies ◽  
Photoelectron Spectra ◽  
Development Fund ◽  
Xps Spectra ◽  
The Core ◽  
Ice Surfaces

&lt;p&gt;&lt;strong&gt;C&amp;#233;line TOUBIN&lt;/strong&gt;&lt;strong&gt;&lt;sup&gt;2&lt;/sup&gt;&lt;/strong&gt;&lt;strong&gt; and &lt;/strong&gt;&lt;strong&gt;Andr&amp;#233; Severo Pereira GOMES&lt;/strong&gt;&lt;strong&gt;&lt;sup&gt; 3&lt;/sup&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;sup&gt;2,3&lt;/sup&gt; Laboratoire de Physique des Lasers, des atomes et des Mol&amp;#233;cules, Universit&amp;#233; de Lille, Cit&amp;#233; Scientifique, 59655 Villeneuve d&amp;#8217;Ascq Cedex, France&lt;/p&gt;&lt;p&gt;E-mail : [email protected]&lt;sup&gt;2&lt;/sup&gt; ; [email protected]&lt;sup&gt;3&lt;/sup&gt;&lt;/p&gt;&lt;p&gt;Ice plays an essential role as a catalyst for reactions between atmospheric trace gases. The uptake of trace gases to ice has been proposed to have a major impact on geochemical cycles, human health, and ozone depletion in the stratosphere [1]. X-ray photoelectron spectroscopy (XPS) [2], serves as a powerful technique to characterize the elemental composition of such interacting species due to its surface sensitivity. Given the existence of complex physico-chemical processes such as adsorption, desorption, and migration within ice matrix, it is important to establish a theoretical framework to determine the electronic properties of these species under different conditions such as temperature and concentration. The focus of this work is to construct an embedding methodology employing Density Functional (DFT) and Wave Function Theory (WFT) to model and interpret photoelectron spectra of adsorbed halogenated species on ice surfaces at the core level with the highest accuracy possible.&amp;#160;&lt;/p&gt;&lt;p&gt;We make use of an embedding approach utilizing full quantum mechanics to divide the system into subunits that will be treated at different levels of theory [3].&lt;/p&gt;&lt;p&gt;The goal is to determine core electron binding energies and the associated chemical shifts for the adsorbed halogenated species such as molecular HCl and the dissociated form Cl- at the surface and within the uppermost bulk layer of the ice respectively [4]. The core energy shifts are compared to the data derived from the XPS spectra [4].&lt;/p&gt;&lt;p&gt;We show that the use of a fully quantum mechanical embedding method, to treat solute-solvent systems is computationally efficient, yet accurate enough to determine the electronic properties of the solute system (halide ion) as well as the long-range effects of the solvent environment (ice).&lt;/p&gt;&lt;p&gt;We acknowledge support by the French government through the Program &amp;#8220;Investissement d'avenir&amp;#8221; through the Labex CaPPA (contract ANR-11-LABX-0005-01) and I-SITE ULNE project OVERSEE (contract ANR-16-IDEX-0004), CPER CLIMIBIO (European Regional Development Fund, Hauts de France council, French Ministry of Higher Education and Research) and French national supercomputing facilities (grants DARI x2016081859 and A0050801859).&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals Efficient Method for the Concentration Determination of Fmoc Groups Incorporated in the Core-Shell Materials by Fmoc–Glycine

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3983
Author(s):  
Elżbieta Szczepańska ◽  
Beata Grobelna ◽  
Jacek Ryl ◽  
Amanda Kulpa ◽  
Tadeusz Ossowski ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Core Shell ◽  
Amino Groups ◽  
The Core ◽  
Transmission Electron ◽  
Model Sample ◽  
Vis Spectroscopy ◽  
Fmoc Group ◽  
Synthesis Procedure

In this paper, we described the synthesis procedure of TiO2@SiO2 core-shell modified with 3-(aminopropyl)trimethoxysilane (APTMS). The chemical attachment of Fmoc–glycine (Fmoc–Gly–OH) at the surface of the core-shell structure was performed to determine the amount of active amino groups on the basis of the amount of Fmoc group calculation. We characterized nanostructures using various methods: transmission electron microscope (TEM), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) to confirm the modification effectiveness. The ultraviolet-visible spectroscopy (UV-vis) measurement was adopted for the quantitative determination of amino groups present on the TiO2@SiO2 core-shell surface by determination of Fmoc substitution. The nanomaterials were functionalized by Fmoc–Gly–OH and then the fluorenylmethyloxycarbonyl (Fmoc) group was cleaved using 20% (v/v) solution of piperidine in DMF. This reaction led to the formation of a dibenzofulvene–piperidine adduct enabling the estimation of free Fmoc groups by measurement the maximum absorption at 289 and 301 nm using UV-vis spectroscopy. The calculations of Fmoc loading on core-shell materials was performed using different molar absorption coefficient: 5800 and 6089 dm3 × mol−1 × cm−1 for λ = 289 nm and both 7800 and 8021 dm3 × mol−1 × cm−1 for λ = 301 nm. The obtained results indicate that amount of Fmoc groups present on TiO2@SiO2–(CH2)3–NH2 was calculated at 6 to 9 µmol/g. Furthermore, all measurements were compared with Fmoc–Gly–OH used as the model sample.

Preparation and Characterization of Core-Shell Latex Containing PDMS in the Shell

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
Baotan Zhang ◽  
Bailing Liu ◽  
Shunsheng Cao ◽  
Xiaobo Deng
Keyword(s):  
Photoelectron Spectroscopy ◽  
Hydrophobic Surface ◽  
Water Repellency ◽  
Atomic Ratio ◽  
Core Shell ◽  
Seeded Emulsion Polymerization ◽  
The Core ◽  
Static Contact ◽  
Ft Ir ◽  
Shell Particles

AbstractIn this paper, the composite latex particles with a polyacrylate (PA) core and a polydimethylsiloxane (PDMS) shell via 3-(methacryloxypropyl)- trimethoxy silane (MPS) as the medium to link the core and shell were prepared by semicontinuous seeded emulsion polymerization and were characterized by transmission electron microscopy (TEM), FT-IR, particle size analyzer and X-ray photoelectron spectroscopy (XPS). The TEM images indicated that the particles containing organic siloxane (D-40) displayed an evident core/shell structure. Additionally, the study by FT-IR and XPS also revealed that D4 could be grafted onto the surface of polyacrylate core because there appeared the characteristic peaks of Si-O-Si group and Si 2s and Si 2p in the spectra of FT-IR and XPS respectively. Besides, the atomic ratio of C/Si on the surface of the core/shell particles (D-40) was close to the ratio of C/Si in the latex of pure PDMS that could prove the PA particles were fully covered by PDMS and the properties of PDMS should be embodied in a maximal level. In order to testify the result, the surface properties of the films produced from the core/shell particles were also investigated by the static contact angle method. Compared with the copolymer of PA, the core/shell particles were more effective to create hydrophobic surface, so, the introduction of D4 was capable of obvious increase in water repellency.

scholarly journals Analysis of the Core Oligosaccharide ofAeromonas hydrophila(Chemotype III) Lipopolysaccharide Using Fast Atom Bombardment, Electrospray and Low Energy Tandem Mass Spectrometry

1994 ◽  
Vol 12 (2) ◽  
pp. 55-68 ◽  
Author(s):  
Joseph Banoub ◽  
Emmanuel Gentip ◽  
Derek H. Shaw
Keyword(s):  
Mass Spectrometry ◽  
Tandem Mass Spectrometry ◽  
Fast Atom Bombardment ◽  
Low Energy ◽  
Tandem Mass ◽  
Core Oligosaccharide ◽  
Molecular Ion ◽  
The Core ◽  
Fragment Ions ◽  
Positive Ion

Fast-atom bombardment mass spectrometry (FAB-MS) was employed for the structural analysis of the core oligosaccharide ofAeromonas hydrophila(Chemotype III) lipopolysaccharide. Positive ion FAB-MS of the underivatized core oligosaccharide gave the protonated molecular ion, confrrming the correct composition in terms of hexoses, heptoses and Kdo which was present as a bicyclic furanosidic lactone. Negative ion FAB-MS gave the deprotonated molecular ion and fragment ions which were derived from more than two cleavage events with charge retention at the reducing and non-reducing terminals. Positive ion F AB-MS of the permethylated core oligosaccharide afforded fragment ions consistent with the defined sequence and branching patterns of the sugar constituents. The electrospray mass spectrum (ESMS) in the positive ion mode of the underivatized core oligosaccharide afforded the protonated molecular ion in the singly and doubly charged forms. Low energy collision-activated dissociation tandem mass spectrometry (CAD MS/MS) analysis of the protonated molecular ion [M+2H]+2provided additional structural data. ESMS of the permethylated and N-acetylated permethylated core oligosaccharides provided useful structural indices and afforded a characteristic pattern for fragmentions resulting from the opening of the methylated bicyclic Kdo furanosidic 1,7- lactone, which was similar to that obtained in the corresponding FAB-MS.

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