High photon energy spectroscopy of NiO: experiment and theory

We have revisited the valence band electronic structure of NiO by means of hard x-ray photoemission spectroscopy (HAXPES) together with theoretical calculations using both the GW method and the local density approximation + dynamical mean-field theory (LDA+DMFT) approaches. The effective impurity problem in DMFT is solved through the exact diagonalization (ED) method. We show that the LDA+DMFT method alone cannot explain all the observed structures in the HAXPES spectra. GW corrections are required for the O bands and Ni-s and p derived states to properly position their binding energies. Our results establish that a combination of the GW and DMFT methods is necessary for correctly describing the electronic structure of NiO in a proper ab-initio framework. We also demonstrate that the inclusion of photoionization cross section is crucial to interpret the HAXPES spectra of NiO.We argue that our conclusions are general and that the here suggested approach is appropriate for any complex transition metal oxide.Comment: 16 pages, 5 figure

Оценивание финансово-экономической безопасности предприятий молокоперерабатывающей отрасли

The essence of the concept “financial and economic security of the enterprise” is covered. Methodological approaches to the enterprise financial and economic security evaluation are considered, enabling the method of index numberrating score of the enterprise financial and economic security to be found. Dynamics of milk anddairy production in Ukraine has been studied. Ukrainian regions leading in liquid processed milk production have been identified. Dynamics of milk and dairy production per man has been analyzed which allowed to find out the annual increase in demand per man. Integrated index of the dairy enterprise financial and economic security has been evaluated. As a result, the ways to increase the managerial efficiency of financial and economic security of the following enterprises:PJSC "Dubnomoloko", PJSC "Kupyans'ki milk canning plant", PJSC the "Yagotyns'ki creamery", PJSC the "Pervomais'ki milk canning plant" are offered.У статті розкрито сутність поняття фінансово-економічної безпеки підприємства. Розглянуто методичні підходи щодо оцінювання фінансово-економічної безпеки підприємства, що дозволило виявити підхід рейтингової оцінки показника фінансово-економічної безпеки підприємства. Досліджено динаміку виробництва молока та молочних продуктів України. Виявити області України, які є лідерами з виробництва молока рідкого обробленого. Проаналізовано динаміку виробництва молока та молочних продуктів на одну особу, що дозволило встановити щорічне зростання попиту на одну особу. Визначено підприємства молокопереробної галузі. Проведено оцінку інтегрального показника фінансово-економічної безпеки підприємств молокопереробної галузі. За результатами оцінки запропоновано шляхи підвищення ефективності управління фінансово-економічної безпеки таких підприємств, як: ПАТ «Дубномолоко», ПАТ «Куп’янський молочноконсервний комбінат», ПАТ «Яготинський маслозавод», ПАТ «Первомайський молочноконсервний комбінат».В статье раскрыто сущность понятия финансово-экономическая безопасность предприятия. Рассмотрено методические подходы относительно оценивания финансово-экономической безопасности предприятия, что позволило выявить поход рейтинговой оценки показателя финансово-экономической безопасности предприятия. Исследовано динамику производства молока и молочных продуктов Украины. Выявлены области Украины, которые являются лидерами по производству молока жидкого обработанного. Проанализировано динамику производства молока и молочных продуктов на одного человека, что позволило установить ежегодный рост спроса на одного человека. Определены предприятия молокоперерабатывающей отрасли. Проведена оценка интегрального показателя финансово-экономической безопасности предприятий молокоперерабатывающей отрасли. По результатам оценки предложены пути повышения эффективности управления финансово-экономической безопасности таких предприятий, как: ПАО «Дубномолоко», ПАО «Купянский молочноконсервный комбинат», ПАО «Яготинский маслозавод», ПАО «Первомайский молочноконсервный комбинат»

Hard X-ray Photoelectron Spectroscopy

In this issue, experts in the field of hard X-ray photoelectron spectroscopy (HAXPES) present their current and upcoming activities at facilities worldwide. Their contributions describe state-of-the-art instrumentation and highlight the great potential of the technique by briefly presenting some recent results. The hope is that this will also give the non-expert an informative overview of the many possibilities offered by HAXPES

Electronic properties of nano-layer structured materials studied by hard X-ray photoelectron spectroscopy

Electronic properties of complex bulk materials, which often exhibit a modified surface electronic structure, and/or at buried interfaces of multi-nm layered samples are accessible by photoelectron spectroscopy using hard X-ray excitation in the multi keV range (HAXPES), where energetic photoelectrons emerge from deeper inside the material due to their significantly increased inelastic mean free paths. Because photoelectric cross sections rapidly decrease with photon energy above ionization thresholds, the use of brilliant and tunable undulator radiation at 3 rd generation synchrotron sources greatly enhances the effectiveness of this technique which is now emerging at storage ring facilities worldwide.HAXPES is a powerful tool for materials science applications as it allows to study as-grown multi-layered structures without a need for prior in-situ surface treatment or sensitive samples which need to be covered by protective capping layers. Since recently, functional materials such as MIM-structures showing resistive switching behavior are being studied by HAXPES even under "in-operando" conditions. An overview will be given on the current state of the technique highlighting its great potential by recent scientific results

Preface to "Recent advances in Hard X-ray Photoelectron Spectroscopy (HAXPES)"

Photoelectron spectroscopy using hard X-ray excitation (i.e. above 2 keV, by definition) has become increasingly popular in recent years because of its invaluable advantages for the study of electronic structure in “real” materials. Due to the energetic photoelectrons, the key additional benefit it provides is bulk sensitivity which is an order of magnitude larger compared to conventional XPS. This extends the well-established capabilities of electron spectroscopy in surface analysis to applications where the electronic and chemical properties of buried interfaces, complex correlated bulk materials and technologically relevant functional materials are at the focus of investigation.Different acronyms for Hard X-ray Photoelectron Spectroscopy have emerged and – judging from results returned by Internet search engines – it seems that “HX-PES” and “HAXPES” are being used most often and with almost equal frequency. Here we prefer HAXPES because it is pronounced easier.HAXPES has gone a long way over many years until its great potential had been recognized by a broader community. Because photoionization cross sections rapidly decrease with photon energy above threshold, both high-intensity X-ray sources and efficient electron spectrometers are needed for sophisticated high-resolution experiments. Ever since well-performing high-voltage electron spectrometers have become commercially available and are being combined with high-brilliance X-ray undulator sources at 3rd generation synchrotron radiation sources, the wide applicability of HAXPES for electronic structure investigation of bulk materials is unfolding in many areas of materials science, both basic and applied. This is reflected by an impressive increase of the number of publications, exceeding 400 in total as of Nov. 2013, since about 2004 when HAXPES activities gained momentum at 3rd generation synchrotron facilities

Hard X-ray PES: chemical and electronic properties of functional materials

Many novel materials for device applications consist of multi-layered nano-structures and their functional properties sensitively depend on the chemical and electronic characteristics in the interface region. Photoelectron spectroscopy (PES) is a well-established effective tool to study electronic and chemical structure at solid surfaces. However, in order to probe technologically relevant complex layered materials of many nm thickness, soft X-ray excitation used in conventional PES is inadequate because of the inherently small probing depth. This is overcome by using hard X-rays in the multi keV range (HAXPES) which produces highly energetic photoelectrons emerging from significantly larger depths inside the material. Itthen becomes possible to also study electronic and chemical properties of complex bulk materials and buried interfaces. State-of-at instruments use brilliant tunable undulator radiation at synchrotron sources in a typical range 3 to 12 keV allowing to obtain detailed information down to a depth of about 10-20 nm. Most interesting for materials science applications is the ability to study as-grown materials without any need for prior in-situ surface treatment or sensitive structures covered by protective metallic layers. Since recently, e.g. functional materials such as MIM-structures showing resistive switching behavior are being studied by HAXPES under "in-operando" conditions. An overview will be given on the current state of the technique highlighting its great potential by recent scientific results on functional materials