Photo-effect

A role is also played by the temperature and frequency dependence of the photocurrent, the variable surface sensitivity at various parts of the cathode and the vector effect of polarized radiation [40]. All the detectors discussed below are electronic components whose electrical properties vary on irradiation. The effects depend on external (photocells, photomultipliers) or internal photo effects (photoelements, photodiodes). 

Photocells and photomultipliers (secondary electron multipliers, SEM) are mainly employed in photometry. These are detectors with an external photo-effect . 

Photo effects, as a function of flat band potential, 481... 

Phosphorus-containing pesticides la 254 Phosphorus insecticides lb 83 Phosphorus pesticides lb 32 Photochemical activation lb 13 Photochemical reactions lb 15,17 Photodiodes la 24,29 Photo effect, external la 24 -, internal la 24, 29 Photo element la 24,29 Photography, exposure times la 137 -, instmmentation la 137 Photomultiplier la 25ff -, disadvantages la 27 -, energy distribution la 26 -, head on la 27 -, maximum sensitivity la 28 -, side on la 27 -, spectral sensitivity la 28 -, window material la 28 Photocells la 25 Phloxime lb 116... 

Shinagawa M, Soramasu N, Mori Y, Okuma T (1977) Studies on the prewave of tellurium and its photo-effect. J Electroanal Chem 75 809-817... 

We are interested in the transmission of y-quanta through the absorber as a function of the Doppler velocity. The radiation is attenuated by resonant absorption, in as much as emission and absorption lines are overlapping, but also by mass absorption due to photo effect and Compton scattering. Therefore, the number Tt E2)AE of recoilless y-quanta with energies EXo E + AE traversing the absorber is given by... 

The thickness of a Mossbauer sample affects not only the strength of the Mossbauer signal but also the intensity of the radiation arriving at the detector because the y-rays are inherently attenuated by the sample because of nonresonant mass absorption caused by the photo effect and Compton scattering as mentioned earlier. The counting rate C in the detector decreases exponentially with the density of the absorber,... 

R. H. Wilson, in Photo-Effects at Semiconductor-Electrolyte Interfaces (A. E. Nozik, ed.), ACS Publishers, Washington DC, 1981. 

We have mentioned microwave ovens a few times already. Although we might employ such an oven regularly, no one has actually seen microwave radiation. The photons are wholly invisible. The phenomenon of sight can be simplified to the photo-effected transformation of a pigment related to retinal within the retina at the back of the eye. Retinal is derived from vitamin A. 

Mixed valency of this sort is the cause of the reflective, gold colour of Nao.3W03. In this system, like the MnfTc ion described above, electrons are excited optically following photon absorption from a ground-state electronic configuration to a vacant electronic state on an adjacent ion or atom. The colour is caused by a photo-effected intervalence transition between adjacent WVI and Wv valence sites ... 

The early years of the twentieth century saw giant advances in man s understanding of nature which must be mentioned in any synopsis of the scientific history of this era. Thus, in 1901, M. Planck (NLP 1918 ) published his first paper on the black-body radiation law which ushered in the era of quantum mechanics. In 1905, A. Einstein (NLP 1918 ) published his Anna Mirabilis Papers on the photo effect, on Brownian motion, and on the theory of special relativity and the equivalence of matter and energy. 

Under light illumination, semiconductor electrodes absorb the energy of photons to produce excited electrons and holes in the conduction and valence bands. Compared with photoelectrons in metals, photoexcited electrons and holes in semiconductors are relatively stable so that the photo-effect on electrode reactions manifests itself more distinctly with semiconductor electrodes than with metal electrodes. 

With the intention of finding a large photo-effect on Tc, the dependence of azobenzene content on the increase in Tc by UV irradiation was measured. The maximum difference in Tc was observed at a very small azobenzene content of... 

Besides the traditional capacitance versus voltage (C/V) measurements, which are mainly used for the characterisation of MOS and EIS capacitances, the scanned light pulse technique (SLPT) was introduced by Engstrom and Aim [13], first for MOS structures. This technique utilises a fight source to illuminate a local area of the MOS structure. Thus, a local photo-effect-induced current can be measured, which only depends on the local properties and energy states of the illuminated region of the MOS structure. In 1988, Hafeman et al. combined this SLPT method with EIS structures to develop the LAPS [14,15]. This sensor is capable of measuring the surface potential of the electrolyte-transducer interface with a lateral resolution. Hence, the surface... 

In the last three j ears many more papers on UPS of adsorbed species have appeared in the literature. At a recent Faraday Discussion (10) on photo-effects in adsorbed layers no less than nine papers dealt with this topic. It is therefore appropriate at the present time to review briefly some of the work that has been done already, to consider which way the subject is leading and to pick out what might be important for experimentalists in the future. In this sense the present article does not set out to be a comprehensive review, but rather a progress report. 

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