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We investigate the thermal reduction of TiO2 in ultra-high vacuum. Contrary to what is usually assumed, we observe that the maximal surface reduction occurs not during the heating, but during the cooling of the sample back to room temperature. We describe the self-reduction, which occurs as a result of differences in the energies of defect formation in the bulk and surface regions. The findings presented are based on X-ray photoelectron spectroscopy carried out in-operando during the heating and cooling steps. The presented conclusions, concerning the course of redox processes, are especially important when considering oxides for resistive switching and neuromorphic applications and also when describing the mechanisms related to the basics of operation of solid oxide fuel cells.

The effects of several ex vacuo methods used in the surface preparation of Cd1−x Zn x Te (CZT) have been studied using noncontact atomic force microscopy, scanning tunneling microscopy, and scanning tunneling spectroscopy. Preparation techniques include mechanical lapping, hydroplane bromine-methanol polishing, and in vacuo annealing. The morphology, electrical homogeneity, and local density of states (LDOS) have been studied for each preparation method. Impurities and oxides quickly form on the surface after each preparation method. Annealing in ultrahigh vacuum causes the surface electronic structure to become inhomogeneous whilst the LDOS suggests a compositional change from an oxide surface to p-type CZT.

In this paper we present scanning tunneling microscopy (STM) investigations of gold with 2,2,6,6-Tetramethylpiperidine (TMP) overlayer. During the STM experiments the creation of holes and hills or no changes of the surface were observed depending on the applied bias voltage and polarity. No modifications were observed in the bias range from −0.5 to +0.5 V. The holes were created for the bias voltages greater than +0.5 V and hills for the bias voltages lower than −0.5 V. The observed changes of the surface morphology suggest the presence of electrochemical reaction between the tip and the surface. Additionally, our results suggest that TMP lowers the electrochemical activation energy of gold to +0.5 eV.

Silicon carbide nanowires (SiCNWs) were efficiently obtained via self-combustion high-temperature synthesis (SHS) route from silicon-bearing/poly(tetrafluoroethylene) (PTFE) mixtures. The SEM and AFM studies were carried out to find out the lengths and diameters of the nanowires (20-100 nm dia. and several microns in length). XPS was used to investigate the chemical composition of the nanowires. These studies showed that the SiCNWs are N-doped. The ARXPS results revealed that outer regions of the nanowires are C-rich. These results along with a low resistance of the nanowires suggest that nitrogen dopant and the carbon rich surface are responsible for good conducting properties of SiCNWs.

The electronic structure of silicon carbide (SiC) nanowires was studied for the first time using scanning tunneling spectroscopy (STS) and current imaging tunneling spectroscopy (CITS). The STS spectra indicated that the surface of nanowires has an n-type semiconducting behavior which is attributed to nitrogen doping of the sample material. The local density of states (LDOS) showed characteristic peaks in occupied and unoccupied part of the spectra. The origin of the LDOS maxima were discussed in contexts of the dopant-induced states, the subsurface defects, and the surface states related to the local reconstruction process. The work shows the applicability to investigate the SiC nanowires by scanning tunneling microscopy and spectroscopy.

Nanoscale studies of four important phenomena – in-situ development of high temperature (HT) wear resistant nanostructured surface glaze, the initial stages of oxidation of TiAl intermetallics, the high temperature degradation of DLC coatings and the property change promoted by nano-patterning of a TiO2 surface are described.

In this paper an atomic force microscopy and scanning electron microscopy analysis of the surface grain structure of negative temperature coefficient of resistance (NTCR) thermistor nickel manganate layers produced by radio frequency (RF) magnetron sputtering, electron-beam evaporation and screen-printing is presented. Thin sputtered and evaporated films exhibited a dense low porosity surface with evidence for grain alignment in a brick layer fashion, whereas thick screen-printed layers displayed perceptible surface porosity. The layer thicknesses and the thickness distributions were analysed by surface profileometry. The three different deposition techniques used for film production are compared and described in detail, including the paste production for screen-printing, deposition conditions and post-deposition annealing and sintering processes for all three techniques. The effects of the differences in the film production processes on the film microstructure are discussed. This is important, because differences in microstructure can result in variations in the resistivity versus temperature characteristics.

Scanning tunnelling microscopy and current imaging tunnelling spectroscopy were used to study the topographic and electronic structure of a reduced TiO2(1 0 0) surface. The STM results showed that the TiO2(1 0 0) surface is capable to form (1 · 7) reconstruction which can transform to (1 · 3) reconstruction due to reoxidation of the surface. The CITS results showed that the (1 · 7) reconstruction is much more metallic in compared to the (1 · 3) reconstruction showing pronounced surface states at energy 1.3 eV and 0.8 eV below the Fermi level and at energy 1.0–1.2 eV above the Fermi level. � 2006 Elsevier B.V. All rights reserved.

Nickel manganate thin films of � 700 nm thickness have been deposited on [1 0 0] silicon substrates using rf magnetron sputtering in an argon atmosphere from optimised targets. Targets were sintered at different temperatures and SEM analysis revealed superior surface density for sintering temperatures of at least 1200 � C. The average grain size increased with sintering temperature and fitted a Rayleigh function. For film growth a substrate temperature of 200 � C proved to be optimal. The effect of subsequent annealing in air from 650 � C to 900 � C in steps of 50 � Co n the microstructure was investigated. X-ray diffraction studies showed that the films re-crystallised from an amorphous-like structure to a cubic spinel phase. A preferred orientation of the film in the [1 0 0] out-of plane crystal direction was strongly pronounced in a temperature window around 200 � C substrate temperature. Films were studied by AFM and showed distinct crystallographic grains (sized � 50 nm) after annealing. The lattice constant of thin films was lower than for the bulk target material, but was not correlated with annealing temperature. � 2005 Elsevier B.V. All rights reserved.

Scanning tunnelling microscopy and current imaging tunnelling spectroscopy were used to observe electronic structure of the edges of monolayer graphite film deposited on the Ir(1 1 1) surface. The electronic structure derived from the tunnelling spectra revealed peak in electron local density of states very close to the Fermi level. This electronic state was interpreted in terms of localised edge state caused by the topology of the π electrons networks typical for the zig-zag edges. The observed maximum of local density of states at about 0.2 eV above the Fermi level was ascribed to the presence of resonant state caused by the appearance of disclinations centres in the vicinity of the graphite edges.

The strategy to perform nanoscale studies of the initial stages of oxidation of TiAl involved first gaining some information on the electronic structure of pure TiO2 surfaces and then on TiAl surfaces before and after oxidation both in low- and high-oxygen potentials. Both materials were studied in atomically-cleaned states generated by repeated sputtering and heating. It was found that the oxygen vacancies created additional defect states in the band gap of stoichiometric TiO2. The results obtained on TiO2 were used as fingerprints to study the oxide nucleation. The results on the initial stages of oxidation of TiAl confirm the nucleation of Ti2O3 islands of nanometer size and monolayer height in a low-oxygen-pressure environment, whilst a TiO2 layer developed in an atmospheric environment. The ledges on atomically-cleaned surfaces usually acted as nucleation sites.

In-situ high temperature scanning tunnelling microscopy and spectroscopy were used to study the influence of temperature on the electronic properties of Ni x Mn 3− x O 3− δ (0.4≤ x ≤1) thin films deposited by r.f. magnetron sputtering at three different oxygen/argon (2.5, 10, 15%) containing ambient. The morphology and distribution of the local density of states (LDOS) of the observed films did not show any difference for the films deposited at different conditions. The distribution of the LDOS was temperature dependent. The changes in the shape of the LDOS observed at 200 °C were reversible with temperature implying that no permanent change of the electronic structure occurred.

The photooxidative degradation of blends (in a full range of compositions) of amorphous poly(vinyl chloride) (PVC) with semicrystalline poly(ethylene oxide) (PEO) in the form of thin films is investigated using absorption spectroscopy (UV- visible and Fourier transform infrared) and atomic force microscopy (AFM). The amount of insoluble gel formed as a result of photocrosslinking is estimated gravimet- rically. It is found that the PVC/PEO blendsisusceptibility to photooxidative degrada- tion differs from that pure of the components and depends on the blend composition and morphology. Photoreactions such as degradation and oxidation are accelerated whereas dehydrochlorination is retarded in blends. The photocrosslinking efficiency in PVC/ PEO blends is higher than in PVC; moreover, PEO is also involved in this process. AFM images showing the lamellar structure of semicrystalline PEO in the blend lead to the conclusion that the presence of PVC does not disturb the crystallization process of PEO. The changes induced by UV irradiation allow the observation of more of the distinct PEO crystallites. This is probably caused by recrystallization of short, more mobile chains in degraded PEO or by partial removal of the less stable amorphous phase from the film surface. These results confirm previous information on the miscibility of PVC with PEO. The mechanism of the interactions between the components and the blend photodegradation are discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 585- 602, 2004

Scanning tunnelling microscopy (STM) and scanning tunnelling spectroscopy (STS) were used to study the electronic structure of the reduced TiO 2 (1 1 0) surface. At the occupied part of the spectra some states at energies of about 1.1 and 0.6 eV below the Fermi level were found. At the unoccupied part of the spectra, the presence of a surface state at an energy of about 0.6 eV above the Fermi level was observed. Their presence has been ascribed to the appearance of Ti 2 O 3 regions on the TiO 2 (1 1 0) surface. High temperature spectroscopy measurements indicated smooth insulator–metal transition (I–M) caused by bands overlap in Ti 2 O 3 , which takes place at elevated temperatures.

The C 60 ONCFn cycloadduct (Fn=ferrocene) was prepared in the reaction between C 60 and ferrocene oxime, the ferrocene derivative was bound to C 60 at the 6–6 bond by a heterocyclic oxygen–nitrogen–carbon ring; the compound was stable in air. The compound dissolved in dichloroethane was deposited on HOPG and observed by UHV STM/STS methods. The molecules of C 60 ONCFn formed several-microns-long straight chains with clearly visible adducted groups pointing to one side of the chain. The STM/STS observations are discussed within the terms of semiempirical quantum chemical molecular modeling.

Nanoscale studies of the thermal oxidation and hydrogenation of graphite surfaces have been investigated using scanning tunnelling microscopy and scanning tunnelling spectroscopy. These techniques have been used to study the electronic states of the islands located at the edges of thermally oxidized and hydrogen-etched graphite surface. Spectroscopy results have shown the presence of Q2g−(π), Q2u−(π), Q2u−(π*), Q2g−(π*), IS and negative differential resistance electronic states recorded over islands of such treated graphite. However, these states vanish on various regions on the thermally oxidized graphite islands. This is ascribed to the disappearance of π/π* bands when the graphite surface oxidizes and indicates the presence of oxygenated groups on the graphite surface.

Molecules that may adopt various stable conformations might be applied to store information. The conformational changes could be induced by suitable polarized tip of STM. For the STM experiments two types of fullerene:ferrocene cycloadducts (C60:Fn) were selected where ferrocene fragment is bound to C60 at the 6-6 bond by different heterocyclic pentagon rings. According to semiempirical quantum chemistry calculation one of them may be used to STM observation without any modification, while the second cycloadduct must be exposed to thermal treatment in order to obtain bistable molecule.

Scanning tunneling microscopy and spectroscopy were used to observe the variations of electronic structure on the carbon nanotube Y-junction. The electronic structure derived from tunneling conductance maps showed natural me- tallic-metallic and semiconducting-metallic transitions close to the Y-junction, and the occurrence of metallic character of the whole Y-junction with the presence of additional resonant state at energy of 0.2 eV below the Fermi level. It is suggested that the state originates from heptagons forming the junction. 2002 Elsevier Science B.V. All rights reserved.

Scanning tunneling microscopy and spectroscopy have been used to study the electronic states of the islands located at the edges of hydrogen-etched graphite surface. Spectroscopy results have shown the presence of additional electronic states, energy gap, and lowering of the Fermi level. The obtained results are in accordance with the theoretical prediction for the presence of p-type tetrahedral amorphous carbon clusters (ta-C/ta-C:H) in perfect sp 2 graphite network.

Scanning tunneling microscopy and spectroscopy have been used to observe the variations of electronic structure along capped carbon nanotubes deposited on freshly cleaved HOPG(0 0 0 1) surface.The electronic structure has been derived from measured dependence of tunneling conductance dI/d< with applied voltage.Evolution of d I/d

Scanning tunnelling microscopy and spectroscopy are used to study electronic states at the edges of the monolayer graphite pits and liquid crystal steps. The graphite edge surface state exhibits a maximum in the local density of states in the energy range of 0.02 – 0.15 eV above the Fermi level. The edge state on the liquid crystal steps is not seen by tunnelling spectroscopy measurements. It is caused by the lack of the carbon zigzag regions leading to specific topology of the π electron networks.

Scanning tunneling microscopy and spectroscopy are used to study the self-assembled 8OCB liquid crystal deposited on the (0001) basal plane of highly oriented pyrolitic graphite. In order to minimize the molecule–molecule interactions the single narrow stripe structures of liquid crystal are created and investigated. The I / V measurements recorded over a single narrow stripe show distinct negative resistance regions or nearly flat regions of the tunneling current. This can be a explained by the resonant tunneling model which includes tunneling via discrete energy levels of the molecule. The Coulomb blockade effect is excluded as a mechanism for the occurrence of nearly flat regions on the I / V characteristics.

Nanostructured tin oxide films were deposited on Si(1 0 0) substrates at room temperature using the PLAD method. Depositions were achieved by using a XeCl * laser, with a fluence of 10 J/cm 2 to ablate a SnO2 target either in vacuum or in an atmosphere containing a relatively low partial pressure (10 � 2 to 100 Pa) of O2. A range of spectroscopic diffraction and real space imaging techniques, SEM, EDS, XRD, and XPS were used in order to characterize the surface morphology, structure, and composition of films. XPS results indicate that the film deposited in vacuum comprises a mixture of Sn, SnO and SnO2 .I n contrast, films deposited in oxygen comprise only SnO and SnO2. This indicates that the deposition of tin oxide films in relatively low partial pressures of O2 prevents the accumulation of unreacted tin metal within the resulting film. SEM studies reveal a sub-micron grain size structure, while XRD analyses indicate that the samples are crystalline, with no evidence for the presence of amorphous material. In this paper we discuss the significance and implications of these findings in terms of the optimization of tin oxide films for use in gas sensing devices and other technological applications. # 2005 Published by Elsevier B.V.

The C60ONCC5H4FeC5H5 cycloadduct was prepared in the reaction between C60 and ferrocene oxime. The compound dissolved in dichloroethane was deposited on HOPG and observed by UHV STM/STS methods. The molecules of C60ONCFn formed long straight chains extending for several microns, and in some of the chains the adducted groups were clearly visible. The dI/dV(V) plots exhibit pronounced maxima interpreted as resonance tunneling to molecular discrete electronic states. The STM/STS observations are discussed within the terms of semiempirical quantum chemical molecular modeling.

Experiments on preparation of C 60 ONCFn cycloadduct (Fn=ferrocene) and C 60 (Cocp 2 ) 3 charge transfer complexes are described and their properties analyzed. The ferrocene derivative is bound to C 60 at the 6-6 bond by a heterocyclic oxygen-nitrogen-carbon ring. The experimental results are compared with the results of modeling using semiempirical quantum chemistry PM3 model. Scanning tunneling microscopy and spectroscopy has been used to observe variation of electronic structure along capped carbon nanotubes deposited on freshly cleaved HOPG(0001) surface. The electronic structure has been derived from measured dependence of tunneling conductance dI/dV on the applied voltage. The evolution of dI/dV(V) along the nanotube are discussed in terms of existing theories of nanotubes and quantum chemistry calculations.

Scanning tunneling microscopy and spectroscopy and X-ray photoelectron spectroscopy were used to study oxidation effects of nitric acid on highly oriented pyrolytic graphite surface. This treatment was performed at different temperatures and etching times with the aim of realizing local binding sites on the surface without creating deep defects. Then these three technics were found in good agreement to characterize the weakly oxidized surface. A wavy structure different from pure graphite at atomic scale was imaged by scanning tunneling microscopy. This modification was correlated to the presence of carboxylic groups on the surface revealed by X-ray photoelectron spectroscopy. Both spectroscopies of scanning tunneling and X-ray photoelectron demonstrated the vanishing of π bands characteristic from sp2 graphitic hybridization. This was attributed to dehybridization corresponding to new bondings of the graphite carbons in the carboxylic groups.

This is a brief review paper on measurements of acoustical properties of sediments in the Polish economic zone of the Baltic Sea. Maps of the distributions of backscattering coefficient and attenuation at 30 kHz are presented. Angular dependences of the backscattering coefficient at 50 kHz and their comparison with theoretical model is also mentioned.

The measurements of the ultrasonic signals backscattered in the water column compared with direct CTD sampling, set in the context of spatial and seasonal variability are presented. The main goal of this research was to find the interrelation between acoustically detected scattering layers like plankton or gas bubbles and the structure of thermohaline field in the Baltic Sea waters.