Electron photon-triggered

The reaction mechanisms of plasma polymerization processes are not understood in detail. Poll et al [34] (figure C2.13.6) proposed a possible generic reaction sequence. Plasma-initiated polymerization can lead to the polymerization of a suitable monomer directly at the surface. The reaction is probably triggered by collisions of energetic ions or electrons, energetic photons or interactions of metastables or free radicals produced in the plasma with the surface. Activation processes in the plasma and the film fonnation at the surface may also result in the fonnation of non-reactive products. 

The minimum energy needed to remove an electron from a potassium metal surface is 3.7 X 10 J. Will photons of frequencies 4.3 X 10 s (red light) and of 7.5 X 10 s (blue light) trigger the photoelectric effect If so, what is the maximum kinetic energy of the ejected electrons ... 

The electrons emitted from the cathode impinge on the anode, releasing photons (soft X-rays). These photons, in turn, trigger photoelectrons from surfaces they strike. The photoelectrons released from the ion collector flow to the anode, i.e. the ion collector emits an electron current, which is indicated in the same manner as a positive ion current flowing to the ion collector. This photocurrent simulates a pressure. This effect is called the positive X-ray effect, and it depends on the anode voltage as well as on the size of the surface of the ion collector. 

Fig. 3.15 Explanation of the X-ray effect in a conventional ionization gauge. The electrons e emitted by the cathode C cottide with anode A and trigger a soft X-ray radiation (photons) there. This radiation strikes, in part the ion collector and generates...

In photo-catalytic and solar energy conversion devices, the absorption of a photon results in the generation of electrons and holes, which, upon separation, can provide an electric potential or trigger chemistry. The efficiency of these devices is frequently determined by the transport of the charges following photo-generation. In particular, for TiC>2-based dye-sensitized solar cells, it has been demonstrated that the efficiency is limited by electron transport through TiC>2 nanoparticles [1]. 

If the operation of the devices considered above on their specific substrate (photon, electron, ion) is triggered by external optical, electrical or chemical stimuli, their features may be switched between two (or more) states presenting different characteristics. Such switching devices are therefore formed by two main components a trigger, the switching unit, activated by an external stimulus and a substrate, the switched species they should operate with efficiency, reversibility and resistance to fatigue. 

In general, optically, electrically or chemically triggered switches would seem to be preferable to mechanically activated ones, as are photo-, electro- and chemo devices with respect to mechano devices and electronic or photonic computing with respect to mechanical computing. The ultimate in (nano)mechanical manipulation of a molecular device is represented by the realization of a bistable switch based on the motion of a single atom by means of the scanning tunnelling microscope [8.295] (see also Section 9.9). 

The time (or dose) dependences of the subbands turned out to be a very precise and sensitive tool to study the defect formation, and STE can be used to both trigger and probe the dynamics of lattice rearrangement in RGS. Figures 5 and 6 show examples of evolution of luminescence spectra of RGS under irradiation by electrons (Fig.5) and photons (Fig.6). In all cases a pronounced increase in the intensity of the defect component during... 

Advances in supra-molecular chemistry have enabled the synthesis of a variety of tailor-made complex molecules, which have been designed to meet different requirements such as a high conductivity, the possibility of switching between two states triggered either by photons or electrons, a stiff rod-like structure and good solubility. 

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