Total internal reflection condition

By the total internal reflection condition at the liquid-liquid interface, one can observe interfacial reaction in the evanescent layer, a very thin layer of a ca. 100 nm thickness. Fluorometry is an effective method for a sensitive detection of interfacial species and their dynamics [10]. Time-resolved laser spectrofluorometry is a powerful tool for the elucidation of rapid dynamic phenomena at the interface [11]. Time-resolved total reflection fluorometry can be used for the evaluation of rotational relaxation time and the viscosity of the interface [12]. Laser excitation can produce excited states of adsorbed compound. Thus, the triplet-triplet absorption of interfacial species was observed at the interface [13]. 

Fig. 6. Normalized fluorescence spectra of cast poly(N-vinylcarbazole) film doped with 6.2x10 mole perylene per mole carbazole unit. (A) total internal reflection condition with =73.6°. (B) normal excitation condition. Both spectra are...

The SPR is operated imder total internal reflection conditions. It means no light is transmitted through the reflecting surface and all light is reflected. To achieve total reflection condition, the RI of the crystal has to be significantly... 

In most realistic cases the fibre is not completely straight in fact, it is exactly this flexibility of optical fibres that make them attractive for use in light delivery systems. Therefore, even when the total internal reflection condition is met initially, losses into the cladding may occur as soon as the fibre is bent excessively. 

S. Tsukahara, Y. Yamada, T. Hinoue, and H. Watarai, Measurement of the rotational relaxation of octadecylrhodamine B adsorbed at a liquid-liquid interface by time-resolved fluorescence anisotropy under the total internal-reflection condition, Bunseki-kagaku, Al, 945-952 (1998). 

These constraints require that surface plasmons cannot be directly excited by incident light, and produce a resonance condition for the wave vector of the evanescent wave which excites the plasmons. Furthermore, indirect SP excitation can only be achieved by an evanescent wave generated by p-polarized incident light under total internal reflection conditions. This occurs when a beam of light propagating through an incident medium (e.g. a prism) of higher refractive index (wq) an interface with a second... 

A feature of interest is the possibility of obtaining the condition of total internal reflection (TIR). Under this condition, the fundamental beam impinges on the interface from the liquid with the highest index of refraction yielding a SH intensity enhancement of more than a hundred times. Two TIR angles exist, given by the following relationships ... 

This type of mode can exist only under certain conditions related to the geometry of the microtube and the refractive indices of the three regions. By defining the incident and reflection angles at r = R and r R2 as 6t and 02, the light transmitted through the inner boundary and totally internal reflected at the outer boundary should satisfy the following three criteria ... 

Under conditions of total internal reflection, guided modes are obtained due to the constructive interference between the light rays propagating through the waveguide30... 

When melted fat or oil is placed on the surface of an ATR crystal like diamond, the infrared light penetrates a distance of only a few micrometers into the test sample, when the conditions of total internal reflection apply... 

For the air/water interface at 25°C, the critical angle c is 43.75°. For values of 0i > 0c, all the light is reflected to the optically dense phase. This condition is called total internal reflection. It is the key condition of optical wave guiding and thus the most fundamental condition of optical sensing. 

FIGURE 6.11. (a) A total internal reflection fluorescence image of the same conditions as shown in Figure 6.10a. (b) Line scan of fluorescence intensity (dotted line) across the microchannels. 

A second important condition concerns the total internal reflection of light. This occurs when the incident and reflected light reside within a medium of higher refractive index relative to the medium supporting the refracted light (nl > n2) and... 

The local field generated by total internal reflection [23] or by the SPR [14-18] can be diffracted by gaining (or losing) discrete momenta Ak = mg, generated by the periodic surface structure of periodicity A (Fig. 4). The diffraction angle deviates in discrete increments from the specular-reflection angle (i.e., zeroth-order diffraction) in fulfillment of the corresponding momentum match condition ... 

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