Conjugate field planes

Another way to suppress stray light is through field stops and aperture stops. A field stop is placed in a conjugate image plane of the excited spot in the sample. An aperture stop is placed most efficiently in the image plane of another aperture, which can be another stop, a lens, or a mirror. Two examples are shown in Fig. 7.29. A lens, LI, focuses a laser beam into a sample. The light emitted by the... 

Information concerning the orientation of the molecule can be inferred from the polarization dependence. NEXAFS is sensitive to bond angles, whereas EXAFS is sensitive to the interatomic distances. Linearly polarized X-rays are best suited for molecules possessing directional bonds. This is best exemplified for flat 7T-conjugated molecules lying flat on surfaces. When the electric field vector E is aligned along the surface normal, features due to the out-of-plane tt orbitals... 

Historically, however, it has been much more common for experimentalists to introduce a new variable into Figure 1, changing either the temperature of one or more samples of fixed composition, or the electrolyte concentration in a series of samples of fixed amphiphile—oil—water ratio. The former constitutes a temperature scan the latter experiment is widely known as a salinity scan. When the temperature of an amphiphile—oil—water system is varied, the phase diagram can be plotted as a triangular prism (because temperature is an intensive or field variable). When a fourth component (eg, NaCl) is added at constant temperature, tetrahedral coordinates, are appropriate (conjugate phases have different salinities, and the planes of different tietriangles are no longer parallel). 

X. Gonze, "First-principle responses of solids to atomic displacements and homogeneous electric fields a conjugate-gradient algorithm, used with plane waves and pseudopotentials," Phys. Rev. B 55 (1997), 10337-10354. 

EFISHG yields projections of the /3 tensor on the direction of the molecular dipole moment (z-axis). Hence a specific linear combination of elements is obtained and not a unique -value that is sufficient to characterize the molecular second-order NLO response. This is a serious limitation of the technique some components of /3 may be large but will not show up in the experimental results because their projection on the direction of the molecular ground-state dipole is zero. However, the use of polarized incident light with polarization directions parallel and perpendicular to the externally applied electric field allows the extraction of further information on the /3 tensor. For planar molecules conjugated in the yz plane, components with contributions of the X direction may be safely ignored. Two linear combinations, /3 and of tensorial elements may then be determined (Wortmann et al., 1993), (123) and (124) ... 

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