Transversal coherence

The transversal coherence length Tc trms is, however, limited. It is given by the expression ... 

Same considerations are valid for spatial coherence. As the advanced wave passes through a narrow aperture, it gains some degree of transverse coherence according to the van Cittert-Zernike theorem. Because the nonlinear interaction is restricted to the area where the pump field is present, the resulting signal (DFG) field is also partially coherent provided the pump beam diameter is smaller than the coherence width of the advanced wave in the plane of the crystal [Aichele 2002],... 

A new element for simultaneous indirect detection of C and signals in labelled proteins was proposed by Uhrin et The CT- CHs, VT- N-HSQC sequence combines constant-time carbon evolution with variable delay nitrogen evolution. This is achieved by the variation of the position of a 90° pulse creating transverse coherence within the C constant-time period. The maximum indirect acquisition time for both nuclei is determined by constant-time period set to l/ /(C,C) = 28.6 ms. The method is best suited for detection of CH3 signals due to their slower relaxation. The proposed element was incorporated into NOESY-based experiments resulting in 3D NOESY-CH3NH and 3D HSQC-NOESY-CH3NH sequences. The experiments... 

Thus the expectation value of a macroscopic observable quantity A, such as the transverse coherence, is given by 1 2-2]... 

The first X-ray scattering experiments of McMillan" on />-n-octyl-oxybenzylidene-/>-toluidine, which exhibits a first order A-N transition, agreed with the mean field theory. On the other hand, CBOOA showed appreciable anisotropy in the temperature variation of the longitudinal and transverse coherence lengths. Later studies on a number of materials have confirmed that anisotropy is a general feature exhibited by all of them. 

The CDW phase coherence length measured by X-ray diffraction increases rapidly below T, For high-quality crystals at about 100 K the longitudinal coherence becomes longer than 1 pirn. At temperatures below 100 K the transverse coherence decreased by applying a current for a while. 

Complete coherence of emission requires spatial (transverse) coherence, related to source divergence, and temporal (longitudinal) coherence, related to source monochromaticity. The undulator has a high spatial coherence, of the order of For example for E= 500 MeV,... 

Frahm J, Hanicke W, Merboldt KD (1987) Transverse coherence in rapid FLASH NMR imaging. J Magn Reson 72 307-314... 

The coherence can be discussed in time and space domains (e.g., Reference 23). The former (temporal coherence or longitudinal coherence) is the correlation between the X-rays at different times. The latter (spatial coherence, transverse coherence, or lateral coherence) is the correlation between the X-rays at different places. 

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