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The systematic features of laser-induced desorption from an SnO2 surface exposed to 10-ns pulsed neodymium laser radiation are studied at the photon energy 2.34 eV, in the range of pulse energy densities 1 to 50 mJ/cm2. As the threshold pulse energy 28 mJ/cm2 is achieved, molecular oxygen O2 is detected in the desorption mass spectra from the SnO2 surface; as the threshold pulse energy 42 mJ/cm2 is reached, tin Sn, and SnO and (SnO)2 particle desorption is observed. The laser desorption mass spectra from the SnO2 surface coated with an organic copper phthalocyanine (CuPc) film 50 nm thick are measured. It is shown that laser irradiation causes the fragmentation of CuPc molecules and the desorption of molecular fragments in the laser pulse energy density range 6 to 10 mJ/cm2. Along with the desorption of molecular fragments, a weak desorption signal of the substrate components O2, Sn, SnO, and (SnO)2 is observed in the same energy range. Desorption energy thresholds of substrate atomic components from the organic film surface are approximately five times lower than thresholds of their desorption from the atomically clean SnO2 surface, which indicates the diffusion of atomic components of the SnO2 substrate to the bulk of the deposited organic film.

The photovoltaic effect has been detected and studied in structures based on ultrathin vacuum-deposited organic films of perylene-3,4,9,10-tetracarboxylic acid dianhydride on the titanium and tin dioxide surfaces. The interfacial potential barrier shape in these structures is studied by low-energy electron total current spectroscopy. Changes in the surface potential upon exposure to visible light are recorded in situ using an electron-beam probe with energies from 0 to 25 eV. The photovoltage is detected at incident photon energies of 1.5–2.5 eV, which corresponds to the organic film absorption range and simultaneously to the transmission band of titanium and tin dioxides. An analysis of the spectral distributions and transient responses shows that two components of the observed photovoltage can be distinguished. The relation of one of the components to the excitation of interband transitions in the organic film and another component to electronic transitions involving interfacial energy states are discussed.

The formation of interfaces between the single-crystalline InAs(001) surface and organic semiconductor molecules (PTCDA and NTCDA) is investigated. With the methods of total current spectroscopy and Auger electron spectroscopy, it is found that indium atoms diffuse from the substrate into the molecular film. Indium atoms present in the film change the structure of its π-electron states and decrease the energy of unoccupied molecular orbitals.

The photoelectronic properties of organic semiconductor-silicon heterostructures (such as PTCDA-Si, CuPc-Si, and OPV-Si) are investigated. The I-V characteristics, as well as the spectral dependences of photoconductivity and photoinduced potential, are measured. Photosensitivity is observed in the absorption bands of both silicon and the organic films. A maximum potential (up to 0.25 V) is observed for the PTCDA-Si heterojunctions. In the OPV-Si heterojunction, the photoinduced potential changes sign under illumination at different wavelengths in the optical range.

The effect of nitrogen-containing substituents such as phenyl imide and actyl imide on the character of fragmentation of perylene derivative molecules under laser irradiation has been studied by laser desorption (LD) mass spectrometry. Replacement of the central oxygen atom by a nitrogen atom in anhydride carboxy groups in perylene tetracarboxylic dianhydride (PTCDA) molecule results in the suppression of CO2 desorption and predominant desorption of CO. The LD mass spectrum exhibits peaks that correspond to fragments of the perylene nucleus and those of the aromatic and aliphatic substituents. Intact PTCDA molecules are present in the desorbed flux in insignificant amounts.

An unoccupied density of states (DOS) evolution under oxidation of ultrathin Mg, Zn and Cd layers on SrTiO 3 (1 0 0)-(2×2) substrates are investigated. The metal deposition and subsequent oxidation were studied in situ under UHV conditions by means of LEED, AES, TCS and work function measurements. An appearance of metal- and oxygen-derived bands of the unoccupied DOS was traced in the TC spectra. Metal oxidation was followed by the hybridization of metal and oxygen orbitals and by the appearance of the mainly O 2p oxygen-derived bands, which are characterized by a set of DOS maxima, located at the following energies (above the Fermi level): 8.0, 11.5, 14.3, 15.0 and 19.0 eV for MgO; 6.0, 8.1, 16.8 and 20.5 eV for ZnO and 7.5, 10.0 and 12.7 eV for CdO. The results obtained are discussed in comparison with previously published experimental and theoretical data on unoccupied DOS in metal oxides.

Low energy electron diffraction, Auger electron spectroscopy, X-ray photoelectron spectroscopy and electron energy loss spectroscopy were used to study a process of electron beam evaporated deposition of magnesium oxide film on a strontium titanate substrate. An annealed substrate exhibited a SrTiO 3 (100)-(2×2) surface reconstruction and consisted of nearly equal areas of TiO 2 and SrO terminated planes (slightly rich TiO 2 ). A selective deposition of magnesium oxide onto TiO 2 terminated planes of strontium titanate substrate was carried out, and a formation of a MgO(100)-c(2×2) superstructure discovered. A plausible nature of the superstructure is discussed in terms of a non-stoichiometric MgO(100) plane with a 1/4 density of oxygen vacancies.

Thin copper oxide film formation on the polar ZnO(0001) and ZnO(0001) surfaces under ultra-high vacuum conditions was monitored by LEED, Auger, TCS and work-function measurements. The 2.5 nm thick discontinuous oxide films contained a mixture of CuO, Cu2O and ZnO. The effect of oxygen gas on the conductivity of the thin films has been measured, and a more pronounced increase of a relative resistance of the film is observed in the temperature range 400–500 K.

Laser-induced oxygen molecule desorption from crystalline (110) and compressed-powder rutile TiO 2 surfaces is investigated by time-of-flight distributions and desorption signal dependencies on laser fluence. A double-component distribution of desorbed O 2 molecules (a fast one and a slow one) justifies validity of both photoelectronic and thermo-activation mechanisms. The defected surfaces are characterized by the more intensive oxygen escape supporting the desorption flow formation via the surface defect sites.

Total current spectroscopy (TCS) was used to study an evolution of unoccupied states through the process of thin-layer copper deposition and its oxidation on polar ZnO(0001) and surfaces. Zn-derived and O-derived unoccupied bands were identified in the TC spectrum at 7.7 and 9.8 eV, respectively, from the clean and well ordered polar ZnO faces, while the spectra from a thin CuO layer reveal an intensive fine structure in the 6 - 25 eV energy range above the Fermi level, which is discussed in comparison with previously reported results of experimental and theoretical investigations. The obtained data provide additional information on the energy location of the edges of unoccupied bands in CuO in the 6 - 25 eV range relative to .

A double-component time-of-flight distribution of laser-desorbed CO 2 molecules was observed for a system of CO adsorbed on ZnO(0001). A strong increase of amount and a lowering of the threshold for the CO 2 desorption was caused by a submonolayer deposition of Cu.

Recent results of surface electronic and geometrical properties of ultrathin copper layers on the crystalline metal-oxide substrates TiO2(110), α-Al2O3(0001), CaO(001), ZnO(1120) and ZnO(0001) are reviewed. The basic experimental data of interest have been obtained by using LEED, AES, PES and EELS. New experimental results on laser-induced desorption (LID) from the system C0/Cu/ZnO(0001) are presented.

Total current spectroscopy (TCS) has been used to probe the {100} surface of a single crystal of vanadium. Primary electron energies were in the range 0–10 eV. Surface potential measurements are described for desorption of residual gas between room temperature and 1500°C. A value for the work function of vanadium is obtained from comparative measurements using evaporated layers of silver. Structure in the TCS curves is a consequence of both the reflection properties of the vanadium surface and excitation of interband transitions in the solid. Additional structure which appears after adsorption is due to resonances in the adsorbed layer. A method is described for the extraction of this component from the spectra and a simple analysis given in terms of multiple electron scattering. In this way estimates of the layer thickness d and the average potential V can be made.