Incident photon energy

Over the temperature interval 165 K to 300 K, the calculations of Silinsh and Jurgis (1985) indicate that the thermalization rate in pentacene decreases from 3 X 1012 to 0.8 X 1012 s 1. The trend is opposite to what would be expected in liquid hydrocarbons and may be attributed to the rapid increase of mcff with temperature. The calculated mean thermalization distance increases with incident photon energy fairly rapidly, from 3 nm at 2.3 eV to 10 nm at 2.9 eV, both at 204 K. With increasing temperature, (r) decreases somewhat. These thermalization distances have been found to be consistent with the experimental photogeneration quantum efficiency when Onsager s formula for the escape probability is used. 

PHOTON ENERGY (eV) Figure 18. Plots of logarithmic absorption coefficient to the incident photon energy for the low-energy tail of the J-band of [CI-MC] with [L-MS], at various temperatures, with [L-MS], at various temperatures. 

We are now able to understand the response of our solid to an electromagnetic field oscillating at frequency >. For the sake of simplicity, we return to the use of expressions (4.17) and (4.18), related to a solid made of single-electron classical atoms, and to only one resonant frequency coq, related to the band gap. Using these expressions, in Figure 4.1(a) we have displayed the dependencies of si and si on the incident photon energy. 

The absolute values of the photoabsorption, photoionization, and photodissociation cross sections are key quantities in investigating not only the interaction of photons with molecules but also the interaction of any high-energy charged particle with matter. The methods to measure these, the real-photon and virtual-photon methods, are described and compared with each other. An overview is presented of photoabsorption cross sections and photoionization quantum yields for normal alkanes, C H2 + 2 n = 1 ), as a function of the incident photon energy in the vacuum ultraviolet range and of the number of carbon atoms in the alkane molecule. Some future problems are also given. 

Figure 2 The photoabsorption (c), photoionization (o-,-), and photodissociation (cr

The recent stage for the study of the spectroscopy and dynamics of the superexcited molecules was comprehensively discussed in Ref. [5], and let us stress that the formation of the superexcited molecules and their decay processes produce a wide range of interesting structures in the c, c, and Cd curves as a function of the incident photon energy. 

In Fig. 7 [7], we compared the photoionization quantum yields (t/,) of CH4, C2H6, and C3H8, which were measured by our group using the double ionization chamber and synchrotron radiation, as described in Section 2.1. The photon energies are considered in two ranges, as follows, in terms of the behavior of the t/, curves as a function of the incident photon energy [7] ... 

The features in C1-C4 normal alkanes discussed in Section 3 seem to be generalized to a wide range of molecules, and thus we conclude that the major part of the photoabsorption cross sections of molecules (cr) is associated with the ionization and excitation of the outer-valence electrons. Hence, there is a strong need to measure the absolute values of a in the vacuum ultraviolet range, particularly in the range of the incident photon energy 10-30 eV, which is covered by the normal incidence monochromator used to monochromatize synchrotron radiation. The photoionization (cr ) and photodissociation (cd) cross sections. 

The elfect of temperature on the absolute values of a, cr,-, and cr as a function of the incident photon energy. All the cross-section data shown in this chapter were measured for molecules in the gas phase at room temperature and thus, the target molecules do not lie in a single energy level as an initial level. This means that the measured cross sections seem to be dependent on gas temperature, which is important in various applications of the cross-section data. 

Figure 24 Incident photon energy dependence of the surface charge separation efficiency (h" / photon) measured by PITCS. Squares, circles, triangles, and diamonds represent the results obtained for Cr-implanted rutile, Cr-doped rutile, undoped rutile, and anatase Ti02 films, respectively.

Depending on their function, radiometers can be either thermal or photon detectors. In thermal detectors, the incident photon energy is converted into heat, which is then measured. The measured data are independent of wavelength. Photon detectors are based on photoelectric effect and measure spectrum intensity. The results are dependent on wavelength. 

In thermal detectors, the incident photon energy is converted into heat, which is then measured. The measured data are independent of wavelength. 

Figure 7.8. Is spectra of vacuum-cleaved, clean flat MgO(lOO) and various water-dosed MgO(lOO) surfaces (3 min exposures at the pressures indicated). One (clean surface) and two component (water-dosed surfaces) fits are shown, along with the fit residual. The incident photon energy was 620 eV. (from [144])...

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