Ghost lines

In addition to primary features from copper in Eig. 2.7 are small photoelectron peaks at 955 and 1204 eV kinetic energies, arising from the oxygen and carbon Is levels, respectively, because of the presence of some contamination on the surface. Secondary features are X-ray satellite and ghost lines, surface and bulk plasmon energy loss features, shake-up lines, multiplet splitting, shake-off lines, and asymmetries because of asymmetric core levels [2.6]. 

Additional secondary features. X-ray satellites, can appear in the spectra if a non-monochromatic source is used moreover X-ray ghost lines show up when the exciting photon originates from impurity elements in the X-ray source. 

The choice of a spectrometer depends on its intended use. Most present-day instruments use a grating as the spectral dispersing element. A wide variety of excellent gratings is currently available. They are supplied with certification as to their precision, blaze efficiency, and freedom from ghost lines, and are generally of high quality. 

Beside X-ray satellites mentioned in the section Source Satellites, characteristic of a nonmonochromatic source, some ghost lines generated by a deteriorated or contaminated anode, by misalignment or by cross linking between Mg and Al anodes may appear. X-ray fluorescence from a subsfrate may induce a secondary excitation in a thin film, creating ghost peaks. 

The fact that = constant x is the linearity advantage of FT-IR spectrometers. It is roughly valid even though the interferometer does not work correctly, for example, in the case of phase errors in the interferogram. Furthermore, no ghost lines exist in the spectrum. However, in the grating spectra ghost lines are possible in the case of malfunction of the instrument. 

Figure 5.17 Rotational Raman spectrum of N2 (the lines marked with a cross are grating ghosts and not part of the spectrum)...

Pure 2D absorption line shapes are readily obtained in heteronuclear 2D /-resolved spectra. The incorrect setting of 90° and 180° pulses can, however, cause ghost peaks that can be removed by a phase cycling procedure, appropriately named Exorcycle (Rutar, 1984b). A... 

Kochendorfer addresses superposition of symmetrical lattice line ghosts originating from the dilation - although it is readily shown that dilatation superposition (Mellin convolution) always causes the observed profile to become asymmetrical [125,126]. 

The Hb solutions generally used are obtained by simple osmotic hemolysis of normal red cells followed by elimination of the ghosts. The molecular heterogeneity of such solutions of adult Hb is revealed by the starch-gel electrophoresis. The Hb line is therefore not quite distinct, which is a minor drawback when the solutions are used for Hp typing. To stabilize the Hb solutions, it is advisable to bubble CO through them before they are ampouled and stored in the frozen state. 

Lyman ghost spect A false line observed in a spectroscope as a result of a combination of periodicities in the ruling. iT-mon, gost)... 

Rowland ghost spect A false spectral line produced by a diffraction grating, arising from periodic errors in groove position. ro,l3nd, gost ... 

Figure 2. Initial zone [100] of aerinite (left hand side) with 1/b = 14.612 A / a= 90° and 1/c = 2.611 A 2 = 5.222 A where every odd line in c direction is extmcted Zone [410] at tilt about c of 14° (right hand side) exhibits ghost reflections indicated by black arrows.

At cold spots the analytes can adsorb to the surface material and only a fraction will reach the detector. Subsequently, the adsorbed compounds can result in ghost peaks in later analyses. Transfer lines from for example, a TD instrument to the GC must be insulated and heated to avoid cold spots . The optimal temperature of the surfaces depends on the stability of the component, pressure, vacuum, etc. Some GC instruments have ceramic insulators at the inlet of the transfer line from for example, TD instruments and this material may act as a cold spot if the line is not heated at the inlet... 

Occasionally, a laboratory will need an in-line detector of radio-labeled molecules. These detectors take the flow from the column or from an initial detector, mix it with fluorescing compound, and measure the fluorescence due to radioactive breakdown. A different system uses beads in the flow cell with an immobilized fluorescing compound, but these systems suffer from ghosting and cannot be used with very hot labeled compounds because of secondary radiation problems. These systems are very useful with tritiated samples and less so with carbon14 labeled compounds. Some success has been reported with sulfur32 label detection. 

Table 8). The same 2pz function is unoccupied in the calculation of the methyl radical in the presence of a ghost lithium atom using the geometry of CH3Li. This shows that the lithium 2pz orbital acts like a normal valence orbital in the description of the C—Li bond and not, as suggested previously,197 198 as a superposition function. The strong charge donation from Li to C is in line with the difference in electronegativity between these atoms, and with the modern picture of a strongly polar carbon-lithium bond.181-183...

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