Effective work functions for ionic and electronic emissions from mono- and polycrystalline surfaces

Kawano, Hiroyuki

doi:10.1016/j.progsurf.2007.11.001

Cited by 128 publications

(71 citation statements)

References 1,053 publications

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“…1, the He level was set to −17.5 eV w.r.t. to E F , which corresponds to a constant upward shift by 2 eV (assuming a work function for Au of 5.1 eV, in good agreement with experimental values 50 ). In comparison, calculations with the He 1s level at −21.0 eV w.r.t.…”

Section: Resultssupporting

confidence: 87%

“…As a first step, the ion fractions were determined based on calculations of with a constant upward level shift by 2 eV. Depending on the work functions of the particular surfaces [(110) and (100): 4.6 eV, poly: 5.1 eV 50,51 ], the 2 eV shift corresponds to a He level at 18.0 eV or 17.5 eV below E F , respectively. Similarly as for Au, only qualitative agreement between theory and calculations was achieved: The relative differences between the different crystal faces are reproduced correctly, but calculated AN rates would have to be increased by more than 30% in order to achieve quantitative agreement with experimental data.…”

Section: Resultsmentioning

confidence: 99%

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Band structure effects in Auger neutralization of He ions at metal surfaces

et al. 2011

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A comparative study of Auger neutralization (AN) of He ions at noble metal surfaces is presented in order to reveal how the electronic structure of the sample influences this charge exchange process. Comparison of calculated ion fractions to experimental data obtained in low energy ion scattering (LEIS) shows that good agreement is achieved only if the relevant aspects of the He-metal interaction are properly taken into consideration. For instance AN depends sensitively on the distance-dependent position of the projectile level, which varies significantly when considering different target materials.

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Section: Resultssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Band structure effects in Auger neutralization of He ions at metal surfaces

et al. 2011

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“…The temperature coefficient is α = −4.58 · 10 −4 eV/K in the experiment temperature range 300-780 K. measurements that α for pure silver (99.99%) is equal to −5.315k, where k = 8.617 × 10 −5 eV · K −1 , in good agreement with the general rule that α for pure metals is generally less than ± a few Boltzmann constants [21]. In addition, this is approximately in accord with the experimental results on silver [22], approximately ten times larger than the theoretical calculations made by DURAKIEWICZ [23] and somewhat lower than the theoretical predictions of Crowell et al [24], and Kiejna [25].…”

Section: A Effect Of Temperaturesupporting

confidence: 88%

A Method for Measuring the Photoelectric Work Function of Contact Materials Versus Temperature

Akbi¹

2014

IEEE Trans. Compon., Packag. Manufact. Technol.

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The nature of the contact material plays a key role to determine the characteristics of electrical arcs and particularly those related to electronic emission. Mechanical and thermodynamic properties as well as electronic emission of such complicated alloys present a lack of reliable and accurate experimental data. The purpose of this paper is to present the development of a method for measuring photoelectric work functions of contact materials. Also reported in this paper are the results of experimental work whose purpose has been the buildup of a reliable photoelectric system and associated monochromatic ultraviolet radiations source, and the photoelectric measurement of the EWF of contact materials. As a first test of the experimental Ultra High Vacuum setup, the electron work functions (EWF) of silver contacts, namely pure polycrystalline metals that are actually used in relays, were measured photoelectrically, using both Fowler's method of isothermal curves and linearized Fowler plots. Ultrahigh vacuum techniques were employed to obtain residual gas pressure of about 5×10 −9 mbar that allows accurate and reliable photoelectric work function measurements. The EWF measured at room temperature of polycrystalline Ag contact (as commercially available) increased from 3.70 eV before heating, to 4.30 eV, and finally, stabilized at the vicinity of 4.26 eV after several vacuum heat treatments at 533 and 773 K. The EWF value obtained, i.e., 4.26 ± 0.03 eV, is in good agreement with the results found in the literature. This shows that the experimental method is valid and the experimental setup is usable. Furthermore, new photoelectric measurements versus temperature have shown a linear decrease of the EWF of silver contacts with increasing temperature, i.e., the temperature coefficient α = dφ/d t is constant and negative α = −4.58 · 10 −4 eV/K in the experiment temperature range 300-780 K.Index Terms-Contact materials, electron work function (EWF), Fowler's Methods, photoemission, temperature dependence, vacuum heat treatment.

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“…The (310) orientation of tungsten has the lowest work function of the prominent low-index planes [25]. Therefore, the majority of electrons is emitted in the forward direction into a single cone with 20 opening angle (FWHM), which is why we chose W(310).…”

mentioning

confidence: 99%

Strong-Field Above-Threshold Photoemission from Sharp Metal Tips

2010

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We present energy-resolved measurements of electron emission from sharp metal tips driven with low energy pulses from a few-cycle laser oscillator. We observe above-threshold photoemission with a photon order of up to 9. At a laser intensity of ∼ 2 × 10(11) W/cm2 the suppression of the lowest order peak occurs, indicating the onset of strong-field effects. We also observe peak shifting linearly with intensity, with a slope of around -1.0 eV/(10(12) W/cm2). We attribute the magnitude of the laser field effects to field enhancement taking place at the tip's surface.

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Effective work functions for ionic and electronic emissions from mono- and polycrystalline surfaces

Cited by 128 publications

References 1,053 publications

Band structure effects in Auger neutralization of He ions at metal surfaces

Band structure effects in Auger neutralization of He ions at metal surfaces

A Method for Measuring the Photoelectric Work Function of Contact Materials Versus Temperature

Strong-Field Above-Threshold Photoemission from Sharp Metal Tips

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