Isochromatics

Inverse Photoemission Spectroscopy (IPES) and Bremsstrahlung Isochromat Spectroscopy (BIS)... 

Iso-chrom, -chromatisch, a. isochromatic. -chron, -chronisch, a. isochronal, isochronous, isochronio. 

The unoccupied part of the density of states can also be measured, by a technique called Inverse UPS (Sometimes also referred to as BIS, Bremsstrahlung Isochromat Spectroscopie). Here a beam of low energy electrons falls on the surface, where they go into the unoccupied states and fall back to the Fermi level, under emission of a quantum hv. Measurement of this radiation as a function of the incident electron energy gives the density of unoccupied states. This technique falls outside the scope of this book. The reader is referred to the literature [5, 44],... 

In inverse photoemission spectroscopy or Bremsstrahlimg Isochromat Spectroscopy, the sample is bombarded with monoenergetic electrons and the Bremsstrahlung radiation is recorded at constant photon energy for varying kinetic energy of the incident electrons. The electronic process involved is just the inversion of the photoemission process, and therefore, instead of investigating occupied states as in UPS/XPS, empty states are examined in BIS. 

Fig. 5. A spin-echo pulse sequence used to determine T, . (a) A (it/2)y pulse puts Mq into the /-direction, and (b) the spin isochromats dephase with time. At a time Ij later, a it pulse is applied along the j -axis, causing the spins to rotate through it radians (c) such that they refocus along the /-aids to form an echo at time 21 (d). The decrease in magnitude of the magnetization vector between stages (a) and (d) provides a measure of (Eq. (4)). All reversible contributions to the T2 process are removed by the application of the it pulse.

Domain region of anisotropy in a carbon form that is distinctively marked by its isochromatic boundary and cleavage (ASTM D-5061). 

F.U. Hillebrecht and M. Campagna, Bremsstrahlung isochromat spectroscopy of alloys and mixed valent compounds 425... 

The optical texture of mesophase and resultant carbons is observed readily by means of a reflected polarized light microscope and may be classified according to the shape and size of the isochromatic units. Such a classification is useful to evaluate the properties of mesophase and carbons such as needle cokes. The mesophase has been defined as the intermediate state which shows optical anisotropy and is quinoline-insoluble at room temperature (5,51) (liquid crystal glass), although it is a viscous liquid crystal during the carbonization process (6). ... 

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