Interpretation linear polarization

Figure 7 shows an aberration-free intensity distribution at the focus of a typical objective lens similar to that used for DLW lithography. Calculations were carried out using a vectorial Debye theory, which accounts for the polarization effects. For the linearly polarized wave it can be seen that the spot is elongated along the polarization vector. To reduce this asymmetry, a X/4-plate can be used to convert the polarization of the incident beam to circular, which can be interpreted as a combination of two mutually perpendicular linearly polarized components. Thus, width of the photomodified line becomes independent of the beam scanning direction in the sample. 

The fundamental requirement for the existence of molecular dissymmetry is that the molecule cannot possess any improper axes of rofation, the minimal interpretation of which implies additional interaction with light whose electric vectors are circularly polarized. This property manifests itself in an apparent rotation of the plane of linearly polarized light (polarimetry and optical rotatory dispersion) [1-5], or in a preferential absorption of either left- or right-circularly polarized light (circular dichroism) that can be observed in spectroscopy associated with either transitions among electronic [3-7] or vibrational states [6-8]. Optical activity has also been studied in the excited state of chiral compounds [9,10]. An overview of the instrumentation associated with these various chiroptical techniques is available [11]. 

The simplest way to show the principal difference between the representations of plane and multipole photons is to compare the number of independent quantum operators (degrees of freedom), describing the monochromatic radiation field. In the case of plane waves of photons with given wavevector k (energy and linear momentum), there are only two independent creation or annihilation operators of photons with different polarization [2,14,15]. It is well known that QED (quantum electrodynamics) interprets the polarization as given spin state of photons [4]. The spin of photon is known to be 1, so that there are three possible spin states. In the case of plane waves, projection of spin on the... 

It is clear that x formally coincide with the three states of spin 1 of a photon. Therefore, one can choose to interpret % ] as the unit vectors of circular polarization with either positive or negative helicity, while Xo gives the linear polarization in the z direction [27]. We note here that to within the sign at % ] the helicity basis (16) coincides with the so-called polarization basis frequently used in optics [57]. 

The investigations presented focus on interpretation of polarization of fluorescence measurements and use of these measurements to study the structure of a representative spectrum of linear synthetic polypeptides, a vinyl polymer, and an intramolecularly cross-linked synthetic polypeptide. The methodological studies investigate the validity of the transition temperature as a structural parameter, the interaction of the fluorescent dye and the polymer to which it is conjugated, and the influence of the dye-polymer interaction on the measurements of various molecular parameters. The structural studies focus on the structure of the random coil, the helix-coil transition, the a-helix to conformation transition in polylysine, and the stability of the spatial structure in intramolecularly cross-linked synthetic polypeptides. 

These studies begin to provide a systematic basis for the detailed interpretation of polarization of fluorescence measurements in structural terms as well as hydrodynamic data about a wide range of linear and cross-linked synthetic polypeptides. The further development of such studies will provide a firm basis for applying polarization of fluorescence techniques to the study of the structure of native proteins in solution. 

The investigations presented in this study focus on the interpretation of polarization of fluorescence measurements and the use of these measurements to study the structure of a representative spectrum of linear synthetic polypeptides, of polyvinylamine, and of a cross-linked synthetic polypeptide. 

In the previous method and interpretation resistivity measurement is used along side linear polarization measurements (see Section 4.12), not as a stand alone technique. 

Both measurements show a fast rising beat structure at negative delaytimes. The origin of this signal results from optical coherence generated by the linearly polarized probe pulse and corresponds to a first-order Free-Induction-Decay. An interpretation of this signal is found in ref. [2]. 

Criteria relating linear polarization measurements to deterioration rates, similar to the ASTM C876 (1991) criteria for half cell potentials, have been published (Broomfield et aL, 1993). These show some comparability between different devices and will be discussed below under interpretation (Section 4.11.4). A set of conversion equations is provided in the final report of the Strategic Highway Research Program (SHRP) contract on corrosion rate measurement (Fliz et al., 1992). 

Most work on linear polarization probes has been done in chloride corrosion condition. Ho vever, the only methods of assessing carbonated concrete are destructive drilling or coring for carbonation depth measurement and trying to interpret half cell potentials which is difficult (Section 4.7.2). Linear polarization is therefore very useful in asse.ssing carbonated structures, particularly as half cell potentials are so difficult to interpret for carbonation induced corrosion. 

J ore vater may not reach the steel, especially in areas of undercutting. It is also very difficult to interpret the measurements. For corrosion rate measurements with the linear polarization technique it is impossible to calculate the area of corrosion. For rehabilitation it is necessary to make electrical connections between all the rebars for cathodic protection or chloride removal. 

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