Ultraviolet Photoemission Spectroscopy UPS

UPS uses a less powerful source of exciting radiation than XPS, such as a Hel discharge lamp emitting radiation of 21.22 eV, or Hell (40.8 eV) for the examination of the valence levels, or shallow core levels, with which the photon will interact, causing ionization and removal of one of these electrons. The low photon energy souree is insufficient to excite deep core electrons. 

Gamma rays X rays Ultra- violet Visible Near IR Infrared Far Infrared Microwave (radar) Television 

Such vibrational transitions occur at about 10 sec which would be effected by light of wavelength cjk where c is the velocity of light, so effective light would have a wavelength of 

The act of vibration is not sufficient by itself for the moleeule to present an IR speetrum and must be associated with a change in the dipole moment of the molecule (the produet of 

The interpretation of IR spectra is helped by the vast library of published spectra, but rehes implicitly on the skill of the spectroscopist. 

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Ultraviolet photoemission spectroscopy( UPS) measurements of a Pd/ SiCVa-Si H structure indicate (Fortunato et al., 1984) that the mechanism responsible for the transport property variations is a change in the contact potential. In these experiments a few angstroms of a-Si have been deposited by an in situ evaporation onto a Pd/SiO substrate. Figure 5 shows the photoemission spectra obtained by synchrotron radiation at a photon energy of 30 eV and for three different conditions (1) after the a-Si deposition, (2) after the H2 exposure at 10-2 Torr for 2 min, and (3) after 02 exposure at 5 X 10-5 Torr and 110°C for 7 min. 

According to a combination of ultraviolet photoemission spectroscopy (UPS), LEED and ion scattering spectroscopy (ISS),53 the PH3 -exposed surface is covered by a P atom layer if annealed to 900 [K], This observation is also made if PH3 is adsorbed on the surface at 900 [K],... 

Ultraviolet photoemission spectroscopy (UPS) has been used to measure the energy levels of small silver particles in a model system. We find that small particles have properties quite different from those of the bulk and that their electron-donating ability increases with size. The UPS difference spectrum of halogen chemisorbed to silver particles changes up to a size of 40 silver atoms, indicating the size range over which chemical properties are size dependent. 

I will illustrate the application of two techniques to the study of problems involving latent-image silver. These techniques are molecular orbital calculations and ultraviolet photoemission spectroscopy (UPS). The calculations are used to model the processes of formation of silver particles through photolysis. The spectroscopic measurements are used to determine properties of the silver particle as a function of its size. 

Recently, the VL shift of 0.6 eV has been measured by means of ultraviolet photoemission spectroscopy (UPS) at the interface between tetrathiafulvalene (TTF) and tetracyanoquinodimethane (TCNQ) [2]. This is one of the largest values for organic/organic interfaces studied so far. Calculations on TTF/TCNQ dimer showed a marked dependence of the charge transfer between two molecules with respect to their mutual geometry, as it is demonstrated in Fig. 1. 

OSITs based on pentacene thin films have been fabricated on TTO formed on glass substrafes. It is well known that the work function of TTO is con-frolled by the method used to clean its surface. OSITs were fabricated based on pentacene thin films wifh a high-work function ITO of 5.3 eV and a low-work function of 4.2 eV. The effect of the work function of ITO on the static characteristics of fhe OSITs was investigated using I-V measurements and ultraviolet photoemission spectroscopy (UPS) [34]. These results provided an important clue, in that the characteristics of the OSITs were strongly associated with the work function of ITO used as a source electrode. In general, the hole injection barrier at the organic semiconductor/metal interface is influenced by the work function of fhe metal. 

This chapter describes fundamental aspects of the electronic structure of organic semiconductors (small molecules and polymers), and their interfaces, and the method to bridge the electronic structure and electrical property more directly using ultraviolet photoemission spectroscopy (UPS). Penning ionization electron spectroscopy (PIES), which is the most surface-sensitive method, is also introduced for study of electronic states at outermost surfaces of solids, which are responsible for charge exchange through the interfaces between different materials when they get contact to form a hybrid system. 

Multilayers of glycine, adsorbed on Ti02 (110), were studied with synchrotron radiation-based UV light [428]. Ultraviolet photoemission spectroscopy (UPS) and XPS data showed the multilayers as formed by glycine molecules in polar zwit-terionic form (NHs CH2COO ). Photon induced damage of multilayers occurs fast (produces a first order desorption of zwitte-rionic molecules with total cross section). 

The calculated very narrow spikes and dips in the density of states due to the hydrogen impurities could, in principle, be detected by ultraviolet-photoemission spectroscopy (UPS) or X-ray-photoelectron spectroscopy (XPS). However, due to a combination of poor XPS resolution and incomplete knowledge of exactly how to treat the background corrections near Cp [known from the XPS determination of the... 

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