V. I. Nefedov

A comparison of different spectrometers and charge corrections used in X-ray photoelectron spectroscopy

The binding energies of the most intense ESCA lines of 16 substances were measured using the following spectrometers: two different VIEE 15, an ESCA 3, in part a McPherson, an AEI ES 100 and a Hewlett-Packard. When taking throughout a charge correction value C 1s = 285.0 eV, the instruments provide the same results with an error of ± 0.3 eV, apart from a few exceptions. A comparison between the C 1s correction and the method of evaporation of thin Au layers shows good agreement when setting Au 4f = 83.8 eV. In this case, it is important to avoid too much Au and any surface reactions.

A study by XPS and XRS of the participation in chemical bonding of the 3d electrons of copper, zinc and gallium

Abstract The participation of 3d electrons in chemical bonds and their part in the formation of valence bands was studied by X-ray photoelectron- and X-ray-spectroscopy for Cu, Zn and Ga phosphides, sulphides and oxides. Incomplete screening of ( n + 1)s,p electrons through the n d shell leads to non-systematic changes of orbital energies and radii of the valence electrons in the first, second and third Group elements. It is reflected in the electronic structure of the respective compounds. A qualitative interpretation of XPS and XRS data for Cu, Zn, Ga phosphides is given. Possible reasons for phosphorus s band splitting for zinc and copper phosphides are considered. The interaction of 3d metal states and 3s, p third Period element states considerably affects the valence band of compounds, and this interaction should be taken into account when considering electronic structures of Cu, Zn and Ga compounds.

Valence-level structure of phosphides of 3d-metals on the basis of XRS and ESCA data

Abstract For the first time, comprehensive X-ray spectroscopic and X-ray photoelectron data have been obtained on the energy spectra of valence electrons in phosphides of the transition metal series: TiP, CrP, MnP, FeP, NiP. Analysis of the experimental data on the electronic structure of phosphides of 3 d -metals in the TiPNiP series indicates that the mechanism of interaction of the M 3 d -states occurring near the top of the valence band with the s,p -states of phosphorus in the following sub-bands resides in the latter being induced near the d -sub-band as a result of the M 3 d —P 3 s,p interaction with the density maximum of the nearest P 3 p -states being oppositely shifted as the number of d -electrons of the metal increases. Analysis of X-ray spectroscopic and X-ray photoelectron data on phosphides of transition metals along with those of metals of groups I(Cu, Ag) and II(Zn, Cd), and comparison of these data with the results of similar studies involving sulphides and silicides of the same metals indicate that the occupancy and the associated position of the d -shell of the metal within the valence band are the determining factors as far as the mutual arrangement of energy sub-bands and the symmetry of respective states are concerned.

Participation of d-electrons of metals of groups I, II, and III in chemical bonding with sulphur

Abstract X-ray photoelectron and X-ray spectroscopic data have been used to study the participation of the d-electrons in chemical bonding and their role in the With increasing metal atomic number within one group the d sub-band increases by ca. 2 eV in group I and by ca. 1 eV in group II. In the sulphur compou

ESCA-untersuchungen zur ladungsverteilung in alkylierten thioharnstoffderivaten und verwandten thiocarbonylverbindungen

Zusammenfassung Die S 2p-, N 1s- und C 1s-Elektronenbindungsenergien einiger substituierter Thioharnstoffe, Isothiouroniumsalze, Thiazolthione, 4,6-disubstituierter 1,3,5-Thiadiazin-2-thione und 1,3,5-Thiadiaziniumsalze wurden mit Hilfe der Rontgenphotoelektronenspektroskopie (ESCA) gemessen. Aus den Verschiebungen gegenuber geeigneten Vergleichsverbindungen wurden Aussagen zur Ladungsverteilung abgeleitet. Hiernach konzentriert sich die positive Ladung der Isothiouroniumsalze an C- und N-Atomen, wahrend in 1,3,5-Thiadiazinium-Kationen ein heteroaromatisches Ringsystem mit delokalisierter Ladung nachweisbar ist.

The variation of silver content in native gold particles as revealed by ESCA

Depth profiling analysis of native gold samples using X-ray photoelectron spectroscopy (XPS) shows the surface layers of lode gold to be significantly enriched with silver to a depth of 0.02–0.04 microns and the surface layers of placer gold to be depleted of silver up to a depth of several microns. The change in the surface composition of gold samples taken from oxidation zones is of more complicated character. Model experiments suggest the surface segregation of silver in lode gold samples to be due to outward diffusion and oxidation of silver at the surface. In placer gold the depletion of silver is caused by leaching of the latter from the surface layers.

The structure of the valence levels of iron nitrosyls from the x-ray photoelectron and x-ray spectra

Abstract On the basis of the X-ray photoelectron spectra of the valence levels and X-ray spectral lines S K β, Fe L α and Fe K β 5 , the structure of the valence levels of Na 2 [Fe(CN) 5 NO] (I), K[Fe 4 S 3 (NO) 7 ] (II) and Na 2 [Fe(NO) 2 (S 2 O 3 )] 2 (III) has been investigated. The level of the bond Fe 3 d -π* (NO) in (I) has been shown to correspond by ∼ 50% to the π (NO) orbitals. In the compounds (II) and (III), the direct FeFe interaction is not essential. The presence of delocalized loosening d *-levels in (II) and (III) increases the length of the FeN bond in these compounds in comparison with that observed in (I).

Electronic structure and bond multiplicity in compounds of the type M2Rh2Ac4Cl2

Abstract The electronic structure of the binuclear complex Rh 2 Ac 4 Cl 2 2− was analysed using X-ray and X-ray photoelectron spectra. The closeness of the structure of Rh 2 Ac 4 Cl 2 2− to two boundary structures ClRhRhCl (I) and Cl… RhRh… Cl (II) has been studied. The correlation between Rh 2 Ac 4 Cl 2 2− and RhCl 6 3− has shown that structure I is more in agreement with the experimental data than structure II. The structure of the K -edge of the spectra provides support for weakening of the RhCl bond.

Complexes of Rh(III) and polyethyleneimine and their catalytic activity in hydrogenation of cyclohexene

Abstract A study was made of mechanisms of complex formation of Rh (III) with polyethyleneimine. It was shown that the polymeric form of the ligand determines special features of the process such as non-equilibrium distribution of the metal between macromolecules, heterogeneity of coordination centres in complexes, and intra-chain types of complex-formation. A study was made of catalytic activity of complexes in hydrogenation of cyclohexene.

New carbonyl complex of palladium

By reducing palladium(ll) acetate by CO in glacial CHsCOOH we obtained a crystalline diamagnetic, yellow compound with the formula Pd2(OCOCHs) sCO (I), which is insoluble in CHCIs, CCI~, and hexane and slightly soluble in benzene and in CHsCOOH. Under the action of 5% HCI complex I decomposes into CO= and CO (totaling 0.5 mole per g-atom of pD), CHsCOOH (1.5 moles per g-atom of Pd), metallic Pd, and PdCI=. In ethanol and in CH~OH I decomposes to form metallic Pd, CHsCOOH, and the corresponding dialkyl carbonate. Upon heating at 60-I05~ 0.5 mole of CO per g-atom of Pd are endothermically evolved, and at 160-180~ the complex decomposes to metallic Pd. The x-ray photoelectron spectrum indicates that all the Pd atoms are identical. The Pd 3d5/2 binding energy is equal to 338.7 eV, and the half-width of the line (2.5 eV) fits the values characteristic of the compounds with equivalent Pd atoms. The following vibrational frequencies were found in the IR spectrum and assigned by comparison with the deuterated analog (cm-1): ~(CH) 2994, 2945, 2920; ~(CO) 1969, 1934;~(CO0) 1555, 1518; 6as(CHs ) 1420; 6s(CH3 ) 1350; ~s(HCC) 1045; ~as(HCC) 1028; ~(CC) 939; 6(0C0) 665; ~as (PdO) 305, 301;~s(PdO) 281 cm -I Among the several possible structures that are consistent with all the available data, including the unusual formal oxidation state of Pd (+1.5), the simplest is a cluster of four Pd atoms, in which there are six acetate bridges and two carbonyl bridges besides the Pd-Pd bonds.