Line wings

The corresponding shape of the isotropic part of the spontaneous Raman band, computed by Fourier transformation of Lorentzian shape, while the line wings decay faster for a finite time scale of the dephasing mechanism. For the halfwidth of the band, on the other hand, only minor changes occur for variable rc. 

In its interpretation a line wing profile is obviously assumed not to overlap with other wings. 

Line wings spectral lines of matrix elements may have a width extending to up to several pm, as is known e.g. from the calcium lines in water samples from the early work on ICP-OES [341]. Here an estimation of the spectral interference for analytical lines situated on the wings has to be made by weighting the intensity contributions at well-defined wavelength differences away from the line center. 

Contributions from band emission spectra, especially in the region of intensive band systems (CN at 370-385 nm, Nj" at 390-400 nm, NH at 340-350 nm, OH at 310-320 nm). Also here weighted corrections, as in the case of matrix line wings may be necessary. 

Figure 132 Spectral interference caused by the broadened line wing of aluminium in the determination of cadmium. (Adapted from R. D. Ediger and F. J. Fernandez, At. Spectrosc., 1980, 1,1)...

As I line at 228.812 nm with the Gd I line at 228.802 nm. In such a case, an alternative line should be used. However, this may also be problematic if the analyte has few sensitive lines, as in the case of cadmium. When a higher resolution spectrometer, such as an echelle spectrometer, is used the lines are farther apart than their physical widths. However, interference is still possible through broadened line wing overlap or stray light. 

A curved background may be the result of a strong concomitant line wing near the analyte peak (Figure 133C). This is a very difficult case to correct,... 

For hard collisions, on the other hand, the collision partners pass through the short-range part of their interaction potential, and the level shift A during the collision is correspondingly larger. Hard collisions therefore contribute to the line wings (Vol. 1, Fig. 3.1) [972],... 

Collisions with 0 > e may shift the absorption frequency of the molecule out of resonance with the laser field. After a hard collision the molecule, therefore, can only contribute to the absorption in the line wings. 

The spectral region within the halfwidth is called the kernel of the line, the regions outside (v < v and v > V2) are the line wings. 

These examples illustrate that in the visible and UV regions, the Doppler width exceeds the natural linewidth by about two orders of magnitude. Note, however, that the intensity / approaches zero for large arguments (v — vq) much faster for a Gaussian line profile than for a Lorentzian profile (Fig. 3.7). It is therefore possible to obtain information about the Lorentzian profile from the extreme line wings, even if the Doppler width is much larger than the natural linewidth (see below). 

The maximum intensity range in which the detector response is linear. It means that the output signal Eg is proportional to the incident radiation power P. This point is particularly important for applications where a wide range of intensities is covered. Examples are output-power measurements of pulsed lasers, Raman spectroscopy, and spectroscopic investigations of line broadening, when the intensities in the line wings may be many orders of magnitude smaller than at the center. 

Figure Metiiods for calculating EPR signtd ren. Left Estimates of siffud intensity are provided by the signed amplitude (4) or amfditude times linewidth squared However, these methods do not account for broad absorbance or line wings (dotted tines). Right. Double integration of EPR signals accounts for the complete area under the EPR dgned.

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