Fullerene “Superhalogen” Radicals: the Substituent Effect on Electronic Properties of 1,7,11,24,27‐C60X5

Hexasubstituted fullerenes with the skew pentagonal pyramid (SPP) addition pattern are predominantly formed in many types of reactions and represent important and versatile building blocks for supramolecular chemistry, biomedical and optoelectronic applications. Regioselective synthesis and characterization of the new SPP derivative, C₆₀(CF₃)₄(CN)H, in this work led to the experimental identification of the new family of “superhalogen fullerene radicals”, species with the gas‐phase electron affinity higher than that of the most electronegative halogens, F and Cl. Low‐temperature photoelectron spectroscopy and DFT studies of different C₆₀X₅ radicals reveal a profound effect of X groups on their electron affinities (EA), which vary from 2.76 eV (X=CH₃) to 4.47 eV (X=CN). The measured gas‐phase EA of the newly synthesized C₆₀(CF₃)₄CN equals 4.28 (1) eV, which is about 1 eV higher than the EA of Cl atom. An observed remarkable stability of C₆₀(CF₃)₄CN^? in solution under ambient conditions opens new venues for design of air‐stable molecular complexes and salts for supramolecular structures of electroactive functional materials.     

Ammonia Borane,NH3BH3: A Threshold Photoelectron–Photoion Coincidence Study of a Potential Hydrogen-Storage Material

We have investigated the photoionization of ammonia borane (AB) and determined adiabatic ionization energy to be 9.26±0.03 eV for the X^{+ 2}E←X ¹A₁ transition. Although the threshold photoelectron spectrum appears at first glance to be similar to the one of the isosteric ethane, the electronic situation differs markedly, due to different orbital energies. In addition, an appearance energy AE_0K(NH₃BH₃, NH₃BH₂⁺)= 10.00±0.03 eV has been determined, corresponding to the loss of a hydrogen atom at the BH₃-site. From the data, a 0 K bond dissociation energy for the B−H bond in the cation of 71.5±3 kJ mol⁻¹ was derived, whereas the one in the neutral compound has been estimated to be 419±10 kJ mol⁻¹.     

Interlaboratory study comparing analyses of simulated angle‐resolved X‐ray photoelectron spectroscopy data

An interlaboratory study has been conducted to determine the following: (i) the similarities and differences of film thicknesses and composition profiles obtained from analyses of simulated angle‐resolved X‐ray photoelectron spectroscopy (ARXPS) data by different analysts using different algorithms for data analysis, and (ii) the effects of two assumptions commonly made in data‐analysis algorithms for ARXPS on derived film thicknesses and composition profiles. The analyzed data were generated by the National Institute of Standards and Technology Database for the Simulation of Electron Spectra for Surface Analysis, (SESSA) which provides a simple way to study the influence of the aforementioned effects on compositional depth profile reconstruction. Sets of simulated ARXPS data were produced for thin films of SiO₂, SiON, HfO₂, and HfON of varying thicknesses on a Si substrate. For some HfON films, the N concentration varied with depth. Eleven groups participated in the round robin study. The majority (eight) employed a commercial ARXPS instrument in which the angular distribution is measured for a fixed sample geometry, in contrast to conventional ARXPS in which the sample is tilted for angular variation. The average deviations between the reported average depth, film thickness, and amount of material typically varied between 20% and 30% but were considerably larger, between 30% and 80%, for some cases. The average errors were generally larger for simulations that included elastic scattering and the finite analyzer‐acceptance angle (realistic conditions) than those for simulations that neglected elastic scattering and the finite analyzer‐acceptance angle (simplified conditions). The retrieved N depth profiles were quantitatively different from the true depth profiles and showed substantial variability among the group of members who used the same instrument and analysis software. Copyright © 2014 John Wiley & Sons, Ltd.     

Studies of protection of iron corrosion by rosin imidazoline self‐assembled monolayers

A type of rosin imidazoline (IM) has been synthesized using rosin acid and diethylenetriamine (DETA) as raw materials. The monolayers of IM were assembled on the surface of iron. The monolayers of the IM inhibitor were characterized by electrochemical impedance spectroscopy (EIS), electrochemical polarization curves and double‐layer capacitance. Surface analysis was carried out to establish the mechanism of corrosion inhibition of iron by X‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy. The IM inhibitor showed good inhibition efficiency for iron in 0.1 M H₂SO₄. The inhibition mechanism of IM inhibitor was interpreted using molecular simulation. Copyright © 2006 John Wiley & Sons, Ltd.     

用X—射线光电子能谱对钇的配位化合物价态的研究

二价的配合物3p能级分裂间距大于三价Y的化合物,二价Y的4s多重分裂也是鉴别Y的价态指纹。     

Electron Counting in Carbaalane Clusters with Cubic Aluminum Core

Extended Hückel Theory (EHT) and Density Functional Theory (DFT) calculations on hexacapped cubic aluminum clusters of the type [(AlH)₈(μ₄-CH)_6−n (μ₄-H) _n ]^+/−q (n ≤ 6) indicate that their favored number of skeletal electron pairs (SEP), 12 SEPs for n ≥ 3, 14 SEPs for n = 2, 16 SEPs for n = 1 and 18 SEPs for n = 0, depends on the relative number of the two types of capping ligands: one-orbital ligands such as H and conical three-orbital CH units. Although only 16- and 18-SEP species have been isolated so far, DFT calculations indicate that 14-SEP clusters of the type [(AlR′)₈(μ₄-CR)₄(μ₄-X)₂]²⁺ (X = one-orbital ligand) should be synthesized. Computed 12-SEP models were not found to be energy minima, but this should not preclude the possibility for stabilizing such species, for example with bulky substituents. Changing the CR capping ligands into AlR units in the above series is expected to limit their electron counts to 12 SEPs. The incorporation of a main-group atom in the middle of the cube does not change the favored cluster electron count. However, calculations indicate that only 12-SEP species are likely to be synthesized. Dedicated to Professor Günter Schmid on the occasion of his 70th birthday     

Analysis of the antitarnish film on a tin surface by x-ray photoelectron spectroscopy and Auger electron spectroscopy

A corrosion-resistant complex film formed in ethylenediaminetetra(methylidenephosphonic acid) (EDTMP) solution was determined by x-ray photoelectron spectroscopy and Auger electron spectroscopy to consist of 48.0% O, 11.7% Sn, 7.7% N, 22.1% C and 10.5% P. From the differences in the binding energies of Sn, N and O before and after film formation and the RPO^2?₃ and SnN vibrations in the Raman spectrum of the film, it was deduced that N and O in EDTMP were coordinated with Sn in the film.     

Synthesis and Spectroscopic Studies of Arylethynylsilanes

A variety of arylethynylsilanes (Ar‐C?C? C₆H₄? C?C)_nSiMe_4?n were prepared successfully by reaction of the corresponding chlorosilanes Me_4?nSiCl_n with Ar? C?C? C₆H₄? C?CM (M=Li, MgBr), which was prepared by treatment of ethynyl(diarylethyne)s Ar? C?C? C₆H₄? C?CH with BuLi or MeMgBr. The ethynyl(diarylethyne)s were readily prepared in good yields by the double‐elimination method: addition of lithium hexamethyldisilazide to a mixture of ArCH₂SO₂Ph, TMS? C?C? C₆H₄? CHO, and ClP(O)(OEt)₂, followed by desilylation. In the tetrakis(arylethynyl)silanes (Ar? C?C? C₆H₄? C?C)₄Si thus prepared, through‐space conjugation of four triple bonds on the silicon atom emerges as a result of participation of the silicon orbitals in the acetylenic π orbitals. This participation enhances the emissive quantum yields of arylethynylsilanes with an increase in the number of arylethynyl moieties on silicon: quantum yields of emission (Φ_F) of 0.72 for (MeOC₆H₄? C?C? C₆H₄? C?C)₄Si, 0.53 for (MeOC₆H₄? C?C? C₆H₄? C?C)₂SiMe₂, and 0.47 for MeO‐C₆H₄? C?C? C₆H₄? C?CSiMe₃ were obtained. Although this enhancement effect was also observed in the phenylethynylarylsilane (MeOC₆H₄? C?C? C₆H₄)₂SiMe₂, the bis(arylethynyl)disilane (MeOC₆H₄? C?C? C₆H₄? C?C‐SiMe₂)₂ exhibited non‐enhanced emission.     

Surface properties of the Ni-Cu-Cr oxide catalyst for dehydrogenative hydrolysis of amines

Catalysts for dehydrogenative hydrolysis of amines, prepared by sorption of copper ions from a solution on a preformed Ni-Cr oxide system, were studied by Auger electron spectroscopy, X-ray photoelectron spectroscopy, and IR spectroscopy of adsorbed CO and NH₃ probe molecules. It was shown that on adsorption copper blocked the chromium ions in the Ni-Cr catalyst with concomitant stabilization as Cu⁺. The incorporation of copper into the Ni-Cr system increased the ability of nickel to reduce water with the formation of oxygen-containing complexes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 288–291, February, 1993.     

电子能谱线形分析研究碳物种的化学状态

利用ＸＰＳ的ＣＩｓ携上峰,Ｘ射线激发供歇线形,ＸＰＳ价带谱以及俄歇电子能谱的ＣＫＬＬ线形研究了几处碳材料的化学状态和电子结构。研究结果表明：ＸＰＳ的携上效应可以鉴别不同结构的碳材料。ＸＡＥＳＲ 化学位移和线形也可以有效地研究中不同的碳材料的成像方式。ＸＰＳ的价带谱电子结构的一种有效方法,对碳材料的研究也很有效。ＡＥＳ的ＣＫＬＬ俄歇线形非常适合金属碳化物的鉴别。     

Vibronic coupling in organic semiconductors: the case of fused polycyclic benzene-thiophene structures

The nature of vibronic coupling in fused polycyclic benzene-thiophene structures has been studied using an approach that combines high-resolution gas-phase photoelectron spectroscopy measurements with first-principles quantum-mechanical calculations. The results indicate that in general the electron-vibrational coupling is stronger than the hole-vibrational coupling. In acenedithiophenes, the main contributions to the hole-vibrational coupling arise from medium- and high-frequency vibrations. In thienobisbenzothiophenes, however, the interaction of holes with low-frequency vibrations becomes significant and is larger than the corresponding electron-vibrational interaction. This finding is in striking contrast with the characteristic pattern in oligoacenes and acenedithiophenes in which the low-frequency vibrations contribute substantially only to the electron-vibrational coupling. The impact of isomerism has been studied as well.     

Analysis of PPMMA films from oxygen plasma using X-ray photoelectron spectroscopy

Plasma polymerized methyl methacrylate (PPMMA) films have been synthesised on silicon substrates in RF glow discharge using oxygen plasma. The electron beam delineation sensitivity of the PPMMA films has been studied systematically by varying oxygen and monomer flow rates. X-ray photoelectron spectroscopy (XPS) analysis clearly illustrates how C/O ratio in the films determines the properties of PPMMA films as electron beam resist. © 1994 John Wiley & Sons, Inc.     

Polyaniline Nanofibrils Array Synthesized within the Anodic Aluminum Oxide Template

Introduction Many methods for the fabrication of nanoparticles have been developed ranging from lithographic techniques to chemical methods. The method termed template synthesis for preparation of a variety of micro- and nano-materials has been explored1-3. The template membranes employed contain cylindrical pores with mono-disperse diameters, that extend through the entire thickness of the membrane. The diameter of this nanocylinder is determined by the diameter of the pores of the template m…     

Revisiting the structural and electronic properties of neutral,mono- and di-anionic titanium-doped silicon clusters TiSin0/−/2− (n = 6-16)

The systematic structures search for neutral and Zintl anionic Ti-doped silicon clusters TiSi_n^0/−/2− (n = 6-16) have been carried out using the ABCluster global search technique combined with a double-hybrid density functional method. Based on the predicted energies, adiabatic electron affinities, vertical detachment energies and the consistency between simulated and experimental photoelectron spectroscopy, the true global minimum structures are confirmed. The results show that structural growth pattern of neutral TiSi_n clusters is from linked structures (n = 10-12) to encapsulated configurations (n = 13-16). In contrast, the evolution pattern of Zintl anionic TiSi_n^−/2− clusters begins with the pentagonal bipyramid structure (n = 6). As the Si atoms increase, these Si atoms attach to the surface adjacent to Ti atom, and gradually surround Ti atom. Eventually, the encapsulated structure is formed when n = 12. Moreover, two extra electrons not only perfect the structure of TiSi₁₂ but also improve its chemical and thermodynamic stability.     

Design and fabrication of an ultraviolet photoelectron spectrometer for the study of free molecules

An ultraviolet photoelectron spectrometer for the study of free atoms and molecules has been designed and fabricated with indigeneous components. The spectrometer consists of a 100 mA HeI discharge lamp, 180° hemispherical electron energy analyser (127 mm mean dia) and electron multiplier ratemeter electron detection systems. The resolution of the spectrometer is 90 meV/and the intensity of N₂ (5σ) band is 10⁵ c/sec. The sample inlet and the collision chamber can be heated to 500 K so that solids of low vapour pressure can be studied. Typical spectra of molecules recorded with the instrument are shown. Contribution No. 373 from the Solid State and Structural Chemistry Unit.