Elemental work function

Trigonal selenium is a -type semiconductor with an energy gap of 1.85 eV (104) and a work function of about 6 eV (105), which is the largest value reported for all the elements. Accordingly, a Schottky barrier should be created at the contact of selenium with any metal. This is consistent with the... 

Cesium was first produced ia the metallic state by electrolysis of a molten mixture of cesium and barium cyanides (2). Subsequentiy the more common thermochemical—reduction techniques were developed (3,4). There were essentially no iadustrial uses for cesium until 1926, when it was used for a few years as a getter and as an effective agent ia reduciag the electron work function on coated tungsten filaments ia radio tubes. Development of photoelectric cells a few years later resulted ia a small but steady consumption of cesium and other appHcations for cesium ia photosensing elements followed. 

A guide to tire stabilities of inter-metallic compounds can be obtained from the semi-empirical model of Miedema et al. (loc. cit.), in which the heat of interaction between two elements is determined by a contribution arising from the difference in work functions, A0, of tire elements, which leads to an exothermic contribution, and tire difference in the electron concentration at tire periphery of the atoms, A w, which leads to an endothermic contribution. The latter term is referred to in metal physics as the concentration of electrons at the periphery of the Wigner-Seitz cell which contains the nucleus and elecUonic structure of each metal atom within the atomic volume in the metallic state. This term is also closely related to tire bulk modulus of each element. The work function difference is very similar to the electronegativity difference. The equation which is used in tire Miedema treatment to... 

Electron-tunneling Model. Several models based on quantum mechanics have been introduced. One describes how an electron of the conducting band tunnels to the leaving atom, or vice versa. The probability of tunneling depends on the ionization potential of the sputtered element, the velocity of the atom (time available for the tunneling process) and on the work function of the metal (adiabatic surface ionization, Schroeer model [3.46]). 

For the same reasons, data on single-crystal faces for metals such as Zn, Sb, Bi, Sn, and Cd have not been plotted in Fig. 15. In order to indicate the probable position of d-metal surfaces, the line described by Eq. (64) has also been drawn in Fig. 15. It is interesting that all the points for sd-metals fall between the sp- and the d-metal groups. The crystal face specificities of Eas0 for Sb and Bi are complicated by their semimetallic nature. In any case, no data on 0 exist for a series of faces of these elements (only electrochemical work functions are available).28,864... 

Alkali metals are strongly electropositive elements with low (2-3 eV) work function and low ionization potential. Upon adsorption on other metal surfaces they cause a severe (up to 3 eV) lowering of the metal work function, as already established by Langmuir in the early 1920 s. 

Michaelson HB. 1977. Work function of elements and its periodicity. J Appl Phys 48 4729-4733. 

Alloys of Au with Ag, Sn, Ni, Pd, Pt, A1 Qiarge between host and Au atoms from trends of isomer shift and work function data (ESCA) correlated with electronegativity of host elements... 

Carburization of rhenium filaments has been used to optimize Th and Pa ionization efficiency for TIMS analysis on single filaments (Esat 1995). ReC has a greater work function than Re metal, and elemental oxidation state is maintained in the reduced or metal state by the presence of carbon in the filament. Using this method and a mass spectrometer with improved ion optics, Esat (1995) was able to improve Th transmission and ionization efficiency by about a factor of 30 over conventional methods. Using more conventional mass spectrometry, Murrell et al. (personal communication) were able to improve ionization efficiency for Pa and Th by a factor of 5-10 over conventional graphite sandwich loads on Re filaments (Goldstein et al. 1989 Pickett et al. 1994). For Pa analysis, one drawback is that Pa and U ionization commonly overlap using this... 

Starting with this definition the semiconductor diemical sensors can be arbitrary classified with respect to following features the type of electrophysical characteristics diosen for monitoring, such as electric conductivity, thermal-electromotive force, work function of electron, etc. type and nature of semiconductor adsorbent used as an operational element of the sensor and, finally, the detection method used for monitoring the adsorption response of electrophysical characteristics of die sensor. 

The TID design proposed Patterson consists of an alkali metal doped cerwlc cylinder, containing an embedded heater surrounded by a cylindrical collector electrode [100]. The ceramic thermionic emitter is biased at a negative potential with respect to the collector electrode, and it is heated to a surface temperature of 400-800 C, depending on the mode of detection. The response of the detector to different elements depends on the electronic work function of the thermionic surface (i.e., the... 

To determine the BEs (Eq. 1) of different electrons in the atom by XPS, one measures the KE of the ejected electrons, knowing the excitation energy, hv, and the work function, electronic structure of the solid, consisting of both localized core states (core line spectra) and delocalized valence states (valence band spectra) can be mapped. The information is element-specific, quantitative, and chemically sensitive. Core line spectra consist of discrete peaks representing orbital BE values, which depend on the chemical environment of a particular element, and whose intensity depends on the concentration of the element. Valence band spectra consist of electronic states associated with bonding interactions between the... 

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