Релятивистским методом дискретного варьирования выполнен расчет электронного строения NoO2 и спектра РФЭС (рентгеновской фотоэлектронной спектроскопии) валентных электронов в диапазоне энергий связи от 0 до ~40 эВ. Наблюдаются значительные эффекты ковалентности в NoO2, обусловленные существенным перекрыванием не только No 6d АО, но и No 6p и No 5f АО с орбиталями кислорода. Построены гистограмма и схема МО, позволяющие понять особенности природы химической связи и структуру спектра РФЭС валентных электронов в NoO2.

The electronic structure of NoO2 and the valence-band X-ray photoelectron spectrum (XPS) in the energy range from 0 eV to 40 eV are calculated by the relativistic discrete variation method. Significant covalency effects are observed in NoO2, which are due to a considerable overlap of not only No 6d AO but also No 6p and No 5f AOs with oxygen orbitals. The MO histogram and scheme are derived, which enable the comprehension of features of the chemical bond nature and the structure of the XPS spectrum of valence electrons in NoO2.

The electronic structure of AnO2 (An = Th‒Lr) and the structure of X-ray photoelectron spectra of their valence electrons were calculated by the relativistic discrete variation method in the MO LCAO cluster approximation (molecular orbitals as linear combinations of atomic orbitals). This structure is in satisfactory agreement with the available experimental spectra. The effective charges QAn of the An ions in AnO2 were determined as the difference between the number of electrons in the neutral An atom and the number of electrons in the actinide ion in the AnO8 cluster. The dependence of the effective charges QAn in AnO2 on the atomic number Z was obtained. The estimated values in the range 0.42 e < QAn < 1.04 e differ significantly from QAn(IV) = 4 e, found in the ionic approximation. This is attributed to the significant covalence effects in AnO2, associated with the overlap of not only An6d, but also of An6p and An5f AOs with the oxygen orbitals. There is qualitative agreement between the obtained QAn values and the values of the chemical shifts (several electron-volts) of the lines of the actinide 4f core electrons in the XP spectra of dioxides relative to the metals.

Релятивистским методом дискретного варьирования (РДВ) рассчитана плотность состояний валентных электронов диоксида EsO2. Построена схема молекулярных орбиталей (МО) валентных электронов и с учетом сечений фотоэффекта валентных электронов построена гистограмма спектра РФЭС (рентгеновской фотоэлектронной спектроскопии) в диапазоне энергий связи электронов от 0 до ~40 эВ. Показано, что в структуру этого спектра вносят вклад электроны внешних валентных (ВМО, от 0 до ~15 эВ) и внутренних валентных (ВВМО, от ~15 до ~50 эВ) МО. Установлено участие Es 5f- и Es 6p-электронов в химической связи. Наблюдается значительное перекрывание не только Es 6d АО, но и Es 6p и Es 5f АО с орбиталями лигандов, что обусловливает высокий вклад ковалентной составляющей в химическую связь в этом диоксиде. Отмечается, что схема МО позволяет понять природу химической связи и структуру спектра РФЭС валентных электронов в EsO2. Показано, что электроны ВВМО на треть ослабляют химическую связь, обусловленную электронами ВМО.

The density of electronic states and the XPS spectrum of FmO2 valence electrons in the binding energy range from 0 to ∼40 eV have been calculated by the fully relativistic method of discrete variation. It is shown that the electrons of the outer and inner valence molecular orbitals (MOs) with binding energies from 0 to ∼15 eV and from ∼15 to ∼40 eV, respectively, contribute to the complex structure of the XPS spectrum of FmO2. The FmO2 MO diagram was constructed and the contribution of the electrons of the outer and inner valence MOs to the chemical bond was estimated.

The density of states of valence electrons of the EsO 2 dioxide is calculated by the relativistic discrete variational method. The scheme of valence molecular orbitals (MOs) is constructed taking into account the photoelectric effect cross sections of valence electrons. The histogram of X-ray photoelectron spectra (XPS) is built for the electron binding energies from 0 eV to ~40 eV. It is shown that the structure of this spectrum contains contributions of outer valence orbitals (OVMOs, from 0 eV to ~15 eV) and inner valence orbitals (IVMOs, from ~15 eV to ~50 eV) molecular orbitals. It is established that Es 5 f and Es 6 p electrons participate in the chemical bonding. It is established that not only Es 6 d , but also Es 6 p and Es 5 f orbitals overlap significantly with ligand orbitals, resulting in a highly covalent chemical bonding in this dioxide. The nature of chemical bonding and the structure of the XPS spectrum of valence electrons in EsO 2 is clarified using the scheme of MOs. It is shown that the chemical bonding formed by OVMO electrons is weaken by one third due to IVMO electrons.

The local environment of thorium in murataite ceramics (Al,Ca,Ti,Mn,Fe,Zr,Th)Ox and ThO2(001) crystalline film on Si(100) substrate as a reference was explored by X-ray absorption spectroscopy (XAS) for the first time. It was found that Th4+ is located in the center of a cube formed by 8 oxygen atoms [r(Th–O) = 2.37 ± 0.03 Å] in murataite ceramics and ThO2 film. The Th4+ second coordination sphere [r(Th–M) ≈ 3.5 Å] in murataite is represented by 3d metals: titanium, iron or manganese

The complex structure of precision X-ray photoelectron spectra (XPS) of valence and core electrons of a ThO2(001) crystal film on Si(100) was obtained and analyzed, and the electronic structure of ThO8, Th13O56, and Th63O216 clusters was calculated. A histogram of the calculated XPS spectrum of electrons of the outer (from 0 to ~15 eV, OVMO) and inner (from ~15 to ~35 eV, IVMO) valence MOs was plotted. The calculated spectrum was in good agreement with the experimental one. Significant overlap of Th 6d atomic orbitals (AO) as well as Th 6p, 5f AO with oxygen orbitals is noted, which brings about the covalent nature of the bond in this dioxide. The contribution of the OVMO and IVMO electrons to the chemical bond was estimated based on the values of the bond populations. It was shown that the IVMO electrons weaken the chemical bond caused by OVMO electrons. It is assumed that the complex structure in the spectra of the Th 5s and Th 5p electrons is largely due to the dynamic effect, which does not allow observing the structure in the spectrum of the Th 5s electrons in ThO2.

The relativistic method of discrete variation has been used to calculate the density of states and the X-ray photoelectron spectroscopy spectrum of valence electrons in the range of electron binding energies from 0 to ~50 eV in PaO2. A scheme of molecular orbitals has been constructed. Significant covalence effects are observed in PaO2, which are associated with the overlap of not only Pa6d atomic orbitals but also Pa6p and Pa5f atomic orbitals with oxygen orbitals. It has been found that the electrons of the inner valence molecular orbitals weaken the chemical bond formed by the electrons of the outer valence molecular orbitals.

Ceramic samples with the following composition (wt %): 50 TiO2, 10 CaO, 10 MnO2, 5 Al2O3, 5 Fe2O3, 10 ZrO2, 10 Ln2O3 (Ln = La, Ce, Nd, Ho) or 10 СеО2, were studied by X-ray photoelectron spectroscopy. According to the data of X-ray phase analysis and scanning electron microscopy, they consist of murataite, zirconolite, and perovskite. In smaller quantities there are crichtonite, pyrophanite-ilmenite, and rutile. Ce3+ dominates in cerium samples: the Ce3+ : Ce4+ ratio is 3 : 1 and does not depend on the method of adding the element to the charge—in the form of СeО2 or Се2О3. All ceramics are dominated by Fe3+, its fraction is 92–94 rel %, while manganese is represented only by Mn3+ cations.

Впервые изучена сложная структура спектров РФЭС (рентгеновской фотоэлектронной спектроскопии) валентных и остовных электронов феррата (VI) калия (K2FeO4), содержащего ионы Fe6+ (3d2). Определены энергии связи остовных Eb(Fe 3p3/2) = 57.8 эВ и Eb(Fe 2p3/2) = 712.1 эВ электронов. Изучен механизм возникновения структуры в спектре Fe 3s-электронов. Экспериментальный спектр Fe 3s-электронов катионов Fe6+(3d2) K2FeO4 состоит в основном из двух линий c расщеплением 2.1 эВ. Эта величина согласуется с результатами теоретического расчета 2.6 эВ для 3d2 (Fe6+), выполненного методом взаимодействия конфигураций.

An intricate structure of the X-ray photoelectron spectra of valence and core electrons of potassium ferrate (VI) (K2FeO4) containing Fe6+ ions (3d(2) ) is studied for the first time. Binding energies of core electrons E-b(Fe 3p(3/2)) = 57.8 eV and E-b(Fe 2p(3/2)) = 712.1 eV are determined. The mechanism of the appearance of the structure in the Fe 3s spectrum is investigated. The experimental Fe 3s spectrum of Fe6+ (3d(2)) cations in K2FeO4 consists mainly of two lines with a splitting of 2.1 eV. This value is consistent with the results of the theoretical calculation (2.6 eV) for 3d(2) (Fe6+) performed by the configuration interaction method.

The Th 5p photoelectron spectrum of the ThO2 oxide exhibits an anomalous spin–orbit splitting, intense satellite, and a poorly observable very strongly broadened Th 5s line. The Th 5p and Th 5s photoelectron spectra are calculated in this work using the configuration interaction and spectral (Green’s) function methods in the basis of atomic Hartree–Fock functions. The results are in good agreement with experiment and indicate that the structure of these spectra is determined by interactions of the photoionization-induced 5p–1 and 5s–1 states with the 5d–25 f (ε f ) and 5p–15d–1(ε f ) satellite states including two holes and one electron in the discrete or continuous spectrum.

The local environment of a novel group of americium (Am3+) complexes with calix[4]arene bearing carbamoylmethylphosphine oxide moieties on the upper rim has been investigated by X-ray absorption spectroscopy. The complexes were obtained by the extraction of americium from aqueous nitric or 2-(1-adamantyl)sulfoacetic acids with the 1,2-dichloroethane solution of this ligand. The correlation of the structures of the obtained complexes with americium distribution coefficients in the corresponding extraction systems is revealed.

In the approximation of the relativistic discrete variation method, the valence X-ray photoelectron spectrum of CmO2 was calculated, and satisfactory agreement with the structure of the experimental spectrum was found. It was shown that the structure of the spectrum is due to the electrons of the outer (from 0 to ~15 eV) and inner (from ~15 to ~35 eV) valence molecular orbitals, which leads to an increase in the covalency of the chemical bond in CmO2. The effective charge of curium in CmO2 was determined, and the contribution of various electrons to the chemical bond was evaluated. A semiempirical scheme of molecular orbitals for CmO2 was constructed.

The electronic structure of CfO 2 is calculated in the fully relativistic cluster approximation of the discrete variation method (RDV). Theoretical X-ray photoelectron spectroscopy (XPS) spectrum of valence electrons is obtained in the range of electron binding energies 0 -…~40 eV. It is shown that outer valence molecular orbitals (OVMOs) in the energy range 0 -…~15 eV are formed by atomic orbitals Cf 5 f and Cf 6 p . The inner valence molecular orbitals (IVMOs) in the energy range ~15 -…~40 eV are formed mainly by Cf 6 p 3/2 and O 2 s AOs. Significant covalent effects in CfO 2 are due to the strong overlap of AOs with the ligand′s orbitals such as Cf 6 d as well as Cf 5 f and Cf 6 p . The structure of MOs formed by Cf 6 d , 7 s , and 7 p AOs differs only slightly from those of dioxides of lighter actinides. These MOs, together with those containing O 2 s and O 2 p AOs, form a “rigid framework” where MOs containing An 5 f AOs move. We suggest a theoretical scheme of MOs that allows understanding the nature of chemical bonding and the structure of the XPS spectrum of valence electrons in CfO 2 .

The first calculations of the electronic structure and X-ray photoelectron spectrum (XPS) of valence electrons of BkO2 in the 0 to ~50 eV range of binding energies are made via relativistic discrete-variational method (RDV). Satisfactory agreement is established between the calculated and experimental spectra of this dioxide, obtained in the works of other authors. A quantitative molecular orbitals (MO) scheme is constructed that allows us to understand the nature of the chemical bonds and the structure of the XPS of valence electrons in BkO2. In contrast to the concepts of the crystal field theory, the effects of covalence in BkO2 are considerable and result in strong overlapping not only of the Bk6d, but of Bk6p, 5f atomic orbitals (AO) with ligand orbitals as well. It is found that the electrons of inner valence molecular orbitals (IVMO) weaken the chemical bonds caused by the electrons of outer valence molecular orbitals (OVMO) by 28%.

New selenates La2O2SeO4 and Pr2O2SeO4, as well as selenite PbSe4+O3 and selenate PbSe6+O4, have been studied by X-ray photoelectron spectroscopy (XPS). The elemental and ionic compositions of new selenates containing Se6+, La3+, and Pr3+ ions have been confirmed on the basis of XPS parameters of the core and valence electrons. The reduction of Se6+ ions on the surface of selenite samples to Se4+ ions under X-ray radiation in the spectrometer chamber has been studied. It has been demonstrated that, unlike the PbSe6+O4 selenate, the PbSe4+O3 selenite is stable to X-ray radiation. It has been shown that La2O2SeO4 is more stable in air than Pr2O2SeO4.