Spectral lines fine structure

Note that the molecules in gaseous phase do not exchange energy with the thermostat so that expression (4.2.17) corresponding to the limiting case ijj — 0 is consistent with the concept of hot electrons (with the frequencies coh + Z,/j4A 1 - )) which accounts for the fine structure of spectral lines of gaseous H-bond complexes.155 The one-sided broadening of the spectral line 2f is proportional to the... 

Fig. 6.3. The significant free —> free components of the spectral functions of molecular hydrogen pairs at 77 K. For a given set of expansion parameters A1A2AL, a different line type is chosen. When two curves of the same type are shown, the upper one represents the free — free, the lower the bound —< free contributions their sum is the total FG al T). The extreme low-frequency portion of the bound — free contributions with the dimer fine structures is here suppressed [282],...

THE SPINNING ELECTRON AND THE FINE STRUCTURE OF SPECTRAL LINES... 

In principle, positronium can be observed through the emission of its characteristic spectral lines, which should be similar to hydrogen s except that the wavelengths of all corresponding lines are doubled. Positronium is also the ideal system in which the calculations of quantum electrodynamics can be compared with experimental results. Measurement of the fine-structure splitting of the positronium ground state has served as an important confirmation of the theory of quantum electrodynamics. 

Other published EPR data show that L-glutamate produces a small axial distortion on the environment of enzyme-Mn(II) with unresolved fine structure and no obvious change in line width. Addition of MgATP results in a diminution of all spectral intensities and the anisotropic spectrum shows poorly resolved fine structure splitting. The appearance of these additional sets of transitions indicates that the environment of Mn2 + at the tight site is changed when metal nucleotide is bound. NH4 + produces additional subtle changes in the EPR spectrum of Mn2+. 

A static NMR spectrum, that representing a non-exchanging spin system, contains full information about the chemical shifts and coupling constants of the system. This is also apparently true for dynamic spectra in the range of slow exchange where the fine structure of the spectrum is still visible. Static spectra are analysed by standard methods which usually consider spectral line positions. (94) Recently methods based on spectral lineshape fitting have been suggested. (95)... 

There are a number of IR bands in GaN either due to transition metal impurities or damage centres. Again, the donor and/or acceptor resonances are often observed on these bands in addition to several IR-specific resonances The first work in this spectral regime involved the Fe3+ luminescence at 1.3 eV by Maier, Kunzer and co-workers [10,22], They studied both MOCVD grown layers (-1 pm thick) and one 40 pm thick Fe-doped VPE sample, which, as mentioned above, was also examined by EPR. The resonance spectra is a 5-line structure due to an S = 5/2 centre as would be expected for Fe3+. They noted that the axial fine structure constant was about 20% larger in the VPE layer (D = -707 x 10"4 cm 1) than in the thin fihns, which they attributed to residual lattice strain in the thin films. There is also a PL line at 1.047 eV which, based on their EPR measurements, Baranov and co-workers [12] have associated with Ni3+. 

Byrne and Ross 5> have considered diffuseness in electronic spectra and have listed some twelve causes of line broadening. In an earlier work 6> they considered in detail a trivial explanation of the broadening, namely spectral congestion, with particular reference to the related molecules benzene, naphthalene, anthracene and tetracene. They showed that for the first three molecules spectral fine structure should be observable under the appropriate experimental conditions, but that for tetracene under practical experimental conditions no resolvable fine structure... 

We have detected a large number of spectral components for all SWCNT Raman bands under consideration. For instance, under excitation with 514.5 nm wavelength, the G-band in our spectrum can be decomposed into eight constituting lines 1516, 1534,1551, 1569,1592.5, 1605,1615, and 1624 cm The reliability of this fine structure is proved by its exact reproduction under excitation with different Xl or at different temperatures as well as by simultaneous observation of the same fine structure for G- and D-bands in the Raman spectra. 

Figure 2.5. The schematic of a typical x-ray emission spectrum, for clarity indicating only the presence of continuous background and three characteristic wavelengths Kai, Kaj, and Kp, which have high intensities. The relative intensities of the three characteristic spectral lines are approximately to scale, however, the intensity of the continuous spectrum and the separation of the Kai/Kaj doublet are exaggerated. Fine structure of the Kp spectral line is not shown for clarity. The vertical arrow indicates the shortest possible wavelength of white radiation, Xsw, as determined by Eq. 2.4.

An isolated atom has a characteristic set of discrete energy levels. Then if one electron is removed from an inner shell of the atom, electronic relaxation occurs due to one of the outer shell electrons filling the electron hole left in the inner shell. This leads to the emission of a characteristic X-ray. In such cases, only one spectral line, originating from the X-ray transition between an inner shell and one of the discrete outer shells, can be observed. However, when multiple ionization occurs during a single excitation process, as in the case of enei etic ion impact, a fine structure or finger pattern is necessarily observed in the spectrum. In PIXE,... 

This is called the fine structure of the spectral lines. Its theory was given by Sommerfeld for the case of atoms of the hydrogen type (H, He+, Li++), and was tested by Fowler and Paschen on the spectrum of singly ionized helium (He+), which was found in complete agreement with the theory. The test is easier wdth He+ than with H for this reason, that the eiu. rgy terms of He+ are four times as far apart, on account of the nuclear charge number Z being doubled, w hereas the... 

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