Phenomenon of complete reflection

Zhu and Nakamura proved that the intriguing phenomenon of complete reflection occurs in the ID NT type potential curve crossing [1, 14]. At certain discrete energies higher than the bottom of the upper adiabatic potential, the particle cannot transmit through the potential from right to left or vice versa. The overall transmission probability P (see Fig. 45) is given by... 

As the excitation process in an external field can be regarded as being a nonadiabatic transition between dressed adiabatic states [32], effective laser control can be achieved by manipulating the parameters of these nonadiabatic transitions directly. Based on this idea, two control schemes have been proposed. The first one is a control scheme for the branching ratio during the molecular photodissociation, achieved by utilizing the phenomenon of complete reflection [24,43,44], The second is to control the population transfer by using a laser pulse with periodically swept parameters [24-29], In both cases the best parameters of the laser pulse can be easily estimated from the ZN theory of nonadiabatic transitions. 

In the following three subsections the Stokes constant U and other basic quantities are presented. Finally in Sec. VI.A.4, the interesting phenomenon of complete reflection is further interpreted. 

This phenomenon implies, however, the following intriguing possibilities (37) (1) bound state in the continuum and (2) switching of transmission in a periodic system. These are explained very briefly. If we put two noninteracting potentials of the type of Fig. 2b, bound states can exist between the two potential units at the energies which satisfy the condition of complete reflection, Eq. (158). In addition, the following quantization condition is, of course, required ... 

The phenomenon of diffuse reflection is easily observed in everyday life. Consider for example the intensity of radiation reflected from a completely matte surface such as a sheet of white paper. The remitted radiation is everywhere of the same intensity no matter what the angle of observation or angle of incidence is. It was the same observation that led Lambert [1] to be the first to attempt a mathematical description of diffuse reflection. He proposed that the remitted radiation flux Ir in an area/ cm and solid angle a> steradians (sr) is proportional to the cosine of the angle of incidence a... 

Nonadiabatic transitions definitely play crucial roles for molecules to manifest various functions. The theory of nonadiabatic transition is very helpful not only to comprehend the mechanisms, but also to design new molecular functions and enhance their efficiencies. The photochromism that is expected to be applicable to molecular switches and memories is a good example [130]. Photoisomerization of retinal is well known to be a basic mechanism of vision. In these processes, the NT type of nonadiabatic transitions play essential roles. There must be many other similar examples. Utilization of the complete reflection phenomenon can also be another candidate, as discussed in Section V.C. In this section, the following two examples are cosidered (1) photochromism due to photoisomerization between cyclohexadiene (CHD) and hexatriene (HT) as an example of photoswitching molecular functions, and (2) hydrogen transmission through a five-membered carbon ring. 

The configuration most often used in SPR instruments relies on the phenomenon of total internal reflectance and was developed by Kretchmann (Fig. 8).71,73 Total internal reflectance occurs when light traveling from a medium of higher refractive index toward a medium of lower refractive index reaches the interface and is reflected back completely into the higher refractive index medium. An important side effect of total internal reflection is the propagation of an evanescent wave across the interface into the medium of lower refractive index. 

Here the sum over surface sites that might have less than full occupancy is denoted as Zsurf, and the structure factor of a CTR is evaluated at the anti-Bragg condition in the last line. The high sensitivity of the reflectivity to the presence of complete and half-occupied layers is not unexpected for a smooth surface, but a remarkable feature of this phenomenon is that this sensitivity is retained even in the presence of the substantial roughening shown in Figures 28C and 28D. In fact, the reflectivity approaches zero whenever a half-occupied layer is found in the surface region. If we include the... 

Available infrared polarizers are either the pile-of-plates type or the wire-grid type. The operation of the pile-of-plates type depends on the phenomenon described on p. 35. That is, at angles of incidence different from 0° the reflection coefficient differs for the two components of polarization. The thin plates, commonly made of AgCl, are placed at a steep angle relative to the beam such that one component is almost completely reflected out of the transmitted beam while the other component is only partially reflected. 

FIG U RE 5.3 One-dimensional model of the control of photodissociation with use of the complete reflection phenomenon. Solid line ground state Vi(r) dotted line excited state V2(r). Two circles represent the nonadiabatic mnnehng type curve crossings between the excited state and the dressed ground state. A vibrationally excited state that dissociates either to the right or to the left is depicted. (Taken from Reference [97] with permission.)... 

For semicrystalline isotropic materials a qualitative measure of crystallinity is directly obtained from the respective WAXS curve. Figure 8.2 demonstrates the phenomenon for polyethylene terephthalate) (PET). The curve in bold, solid line shows a WAXS curve with many reflections. The material is a PET with high crystallinity. The thin solid line at the bottom shows a compressed image of the corresponding scattering curve from a completely amorphous sample. Compared to the semicrystalline material it only shows two very broad peaks - the so-called first and second order of the amorphous halo. 

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