An ESCA investigation of some copper complexes

A series of copper complexes have been investigated by ESCA. All complexes were salts of the tetraphenylphosphonium ion. The binding energies of all the atoms in the complexes were determined. From the binding energies of the ligand atoms we estimated the effective charges on these atoms. For this purpose we used linear relations of the formE_b = kq + E_bO which had been established previously within our scheme of C 1s (phenyl) as internal standard. From the data thus obtained, the effective charge on the copper atom was estimated. A linear relation between binding energy and the effective charge on the copper atom was found, i.e.,E_b(Cu) = 1.52q_Cu + 932.2ESCA spectra were recorded for the complexes bis(1,3-diphenyl-1,3-propanediono) copper (II) and bis(3-phenyl-2,4-pentanediono) copper (II). By a combination of the XPS binding energies and IR intensities of the ν_CH vibrations of the phenyl groups in the complexes with empirical relations between these entities and the effective charges of the atoms and groups, a fairly complete mapping of the charge distributions of these complexes has been achieved.     

An ESCA investigation of some dithiooxalato complexes

A series of dithiooxalato complex ions have been investigated as their tetraphenyl-phosphonium and potassium salts. Core-electron binding energies (E_b) of S, C, and O were determined, as well as those of the metals. From the first-mentioned data, effective charge values (q) were estimated for the atoms of the ligands. For this purpose linear relations (E_b = k · q + E_bO) were used that had been previously derived within a scheme using C ls (phenyl) as the internal standard. From the data thus obtained the effective charge on the metal atoms could be estimated. The data is used to test if analogous linear relations also hold for the heavy elements; for example, we have found E_b(Pt) = 3.17 · q_pt + 71.1 eV.     

ESCA investigation of the oxide layers on some Cr containing alloys

Cr is an important constituent of many technically important alloys, such as stainless steels and those used for metal implants. The following characteristics of such alloys are revealed by ESCA measurements: (1) Heating the sample in air below 400°C leads to oxide layers with high contents of Fe or Co oxides. For temperatures higher than 400°C the Cr becomes mobile enough to migrate to the surface and to build up Cr-enriched oxide layers. (2) In H₂O and HNO₃ a Cr-rich oxide layer is always observed. (3) The chemical shift for Fe oxide in stainless steels is smaller than for pure Fe or Fe-Si alloys; i.e. there is a larger amount of Fe(II) oxide. (4) The intensity ratio Fe_metal : Cr_metal or CO_metal : Cr_metal after exposure of the sample to H₂O or HNO₃ is lower than for oxidation in air, i.e. Cr is enriched not only in the oxide layer but in the metal underneath. (5) If the alloy also contains Mo, the intensity ratio Cr_oxide : Mo(VI)_oxide is about 10 : 1 for exposure to H₂O, as well as to diluted and concentrated HNO₃. In H₂O and diluted HNO₃, Mo(IV) is found also.The ESCA results were obtained without any ion bombardment because the sampling depth is large enough to permit analysis of oxide layers below contamination and even of the metal below a thin oxide layer. This non-destructive method is of great advantage because in ion bombardment of the sample Cr is preferentially sputtered.     

ESCA studies of some niobium compounds

Binding energies of $\text{3d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ level of niobium in some of its compounds have been investigated using X-ray photoelectron spectroscopy. The shift ΔBE in binding energy of $\text{3d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ level of niobium in its several compounds with respect to that in niobium metal can be expressed by the relation ΔBE = i[B_5s + (m ? 1)B_4d], where i and m are the overall ionicity and valence of niobium in a compound.     

Tribochemical reduction of Pb in Pb containing glazes: An ESCA investigation

Most white glazes, used in the ceramics industry for the coating of tiles, show deep, black scratches after tribological treatment with other glazes. Contrary to similar scratches produced during scraping with metals, these failures cannot be removed by polishing. ESCA investigations on Pb containing transparent and white glazes have shown unambiguously that during the tribological treatment the Pb in the surface of the glaze is partially reduced to metallic Pb which could at least partially explain the deep, black scratches seen on the tiles after the treatment.     

ESCA studies of some copper and silver selenides

Photoelectron and Auger spectra have been obtained for the copper and silver selenides CuSe, Cu ₂Se, Ag ₂Se, and AgCuSe as well as from CuS, Ag ₂O, Ag ₂S, Cu, and Ag. Binding-energy values, chemical shifts, and peak-shapes are reported for the Cu 3 d, Ag 4 d and Se 3 p electrons. Absence of multiplet splitting and shake-up structure is discussed in relation to the magnetic properties. It is shown that chemical shifts are much better revealed in the Auger spectra (Cu L₃M_4,5M_{4, 5} and Ag M₅N_{4, 5}N_{4, 5}) than in the direct photoelectron ones. In addition the use of the Auger parameter to characterize the series under study is emphasized. Finally the valence-band spectra have been examined and the electronic structures are interpreted.     

ESCA study of Ni(II) dithiocarbazato complexes

N 1s, S 2p and Ni 2p_3/2 binding energies for the Ni(II) dithiocarbazates and N 1s and S 2p binding energies for the methyl esters of dithiocarbazic acids were measured. It was found that the band width of N 1s narrows on going from the esters to the complexes, thus suggesting a closer similarity between the two nitrogen atoms as a consequence of coordination. S 2p binding energies were found to be similar in the above complexes independent of the chromophore present in them. A possible explanation is suggested for this unusual result.     

An ESCA study of organosilicon compounds

The silicon 2p electron binding energies have been measured for a series of 33 organosilicon compounds. The binding energies are correlated with partial atomic charges calculated by various electronegativity models and CNDO calculations. Group shifts are reported for various chemical groups attached to silicon and are found to correlate with group shifts reported for carbon and phosphorus compounds.     

An yttrium Mξ source for ESCA

A new source for producing YMξ radiation in an ESCA spectrometer is described. The system makes use of continuous evaporation of yttrium on a rotating anode. It is demonstrated that this scheme allows YMξ-excited electron spectra to be recorded without gradual loss of resolution and intensity due to anode oxidation. Electron spectra of Ar, Hg and N₂ excited by YMξ radiation are studied. Relative photoelectric cross-sections of the 5d_{$\text{5}\text{2}$}, 5d_{$\text{5}\text{2}$} and 6s orbitals in Hg and the four valence orbitals in N₂ are measured. The valence electron shake-up spectrum of N₂ is discussed.     

Theoretical investigation of the optical and EPR parameters for VOion in some complexes

The molecular orbital coefficients and the EPR parameters of trisodium citrate dihydrate, sodium hydrogen oxalate monohydrate, potassium d-gluconate monohydrate and L-Alanine vanadyl complexes are calculated theoretically. Two d-d transition spectra and EPR parameters for the VO²⁺ complex are calculated theoretically by using crystal-field theory. The calculated g and A paramaters have indicated that paramagnetic center is axially symmetric. Having the relations of g_∥〈g_⊥〈g_e and A_∥〉A_⊥ for VO²⁺ ions, it can be concluded that VO²⁺ ions are located in distorted octahedral sites (C_4v) elongated along the z-axis and the ground state of the paramagnetic electron is d_xy.     

Satellites in ESCA inner-shell spectra of 3d0 transition metal complexes

The occurrence of satellites to inner shell ESCA spectral lines is discussed for ions in the beginning of the transition metal series. It is found that the satellites correspond to e′_g → e″_g and t′_2g → t″_2g shake-up transitions, where e″_g and t″ _2g have mainly metal ion 3d-character. The intensity is found to increase with relaxation charge transfer and to decrease with the 3d occupancy in the neutral ground state.     

An ESCA study of the molecular core binding energies of the fluorobenzenes

The molecular core binding energies of the complete series of the fluorobenzenes have been measured using ESCA. The experimental values are interpreted in terms of all valence electron CNDO/2 SCF MO calculations. The measured binding energies have been used, in conjunction with previous data, to calculate charge distributions. Some comment is made on linewidths and charging effects.     

An X-ray photoelectron spectroscopic study of some nickel (II) amine complexes

The X-ray photoelectron (XPS) spectra of several Ni(II) diamine complexes, a Ni(II) triamine complex and several Ni(II) diimine complexes are reported in terms of the Ni 2p, Cl 2p and N 1s core level binding energies. Theoretical models are presented to account for the quadratic relationship observed between XPS Ni 2p_{$\text{3}\text{2}$}binding energy shifts and the N-H infrared rocking frequency as related to these complexes. On the basis of this correlation, it is possible to discriminate between free counter-ions coordinated to the metal or involved in cluster-ion formation. Individual XPS data for these complexes are interpreted in terms of the intrinsic nature of the metal environment and an attempt is made to calculate the metal and donor nitrogen atomic charges for selected complexes.     

An ESCA study of Sn organometallic compounds: Solid state broadening effects

X-ray photoelectron spectra have been recorded for a number of solid and gaseous organotin compounds. Solid-state charging effects (such as differential charge broadening) can be large, though we have almost eliminated them by subliming very thin films onto platinum metal. In this way, we have obtained solid-state Sn 3d line widths that are within 10% of the analogous gas-phase values. The quality and reproducibility of the solid-state spectra likewise approach those of gases.The general correlation between ESCA Sn 3d line widths and Mössbauer quadrupole splittings indicates that the broadening of the Sn 3d lines is due to crystal-field splitting from the C₂⁰ term (the quadrupole term) in the crystal-field expansion. There is a general correlation between ESCA binding energies and Mössbauer isomer shifts for the solids.     

An ESCA study of the molecular core binding energies of the chlorobenzenes

The carbon 1s and the chlorine 2s and 2p molecular core binding energies of the complete series of chlorobenzenes have been measured. The assignments of the C 1s binding energies are discussed in terms of CNDO/2 SCF MO calculations and the effect of including and excluding d orbitals in the basis set for chlorine is investigated. The measured binding energies have been used to calculate experimental charge distributions within the molecules.     

An ESCA study of iron sulfidation in H2S

The surface reaction of polycrystalline iron with H₂S has been studied in situ by means of ESCA in the temperature range 100–773 K for H₂S at     

ESCA studies of Cr-Co alloys

ESCA examination of films formed on Cr-Co alloys after immersion in 0.1M NaCl for 24 h has shown that the thickness of passive films decreased with an increase in chromium content. Surface films consisted of chromium and cobalt oxides as Cr₂O₃ and CoO. The amount of CoO in the surface film of the alloy was decreased with an increase in chromium but Cr₂O₃ was found at a greater depth in the passive film at any composition. Cr₂O₃ was a major component of the surface film when the chromium content in the alloy was 10% or higher. Electrochemical techniques according to ASTM G59 and ASTM G5 were used for the determination of the relative corrosion rate. Both Co-10 wt.% Cr and Co-30 wt.% Cr alloys investigated showed a lower corrosion rate than the Co-5 wt.% Cr alloy. Corrosion rate measured could be correlated to the surface film composition and structure as determined by ESCA.