Line width, determination

Overlapping peaks were resolved into their individual components by use of a DuPont 310 curve resolver (an analog computer). The detailed deconvolutions were based on a knowledge of line widths determined from the homopolymers and model compounds studied previously.( ) Studies have shown that for indi-... 

The width and shape of the energy loss peaks in HREELS are usually completely determined by the relatively poor instrumental resolution. This means that no information can be obtained from HREELS about such interesting chemical physics questions as vibrational energy transfer, since the influence of the time scale and mechanism of vibrational excitations at surfaces on the lifetimes, and therefore the line widths and shapes, is swamped. (Adsorbates on surfaces have intrinsic vibra-... 

The recipe (5.58) is even more sensitive to the high-frequency dependence of kjj than similar criterion (5.53), which was used before averaging over kinetic energy of collisions E. It is a much better test for validity of microscopic rate constant calculation than the line width s j-dependence, which was checked in Fig. 5.6. Comparison of experimental and theoretical data on ZR for the Ar-N2 system presented in [191] is shown in Fig. 5.7. The maximum value Zr = 22 corresponding to point 3 at 300 K is determined from the rate constants obtained in [220],... 

The effective resolution is determined by the number of data points in each domain, which in turn determines the length of t and <2- Thus, though digital resolution can be improved by zero-filling (Bartholdi and Ernst, 1973), the basic resolution, which determines the separation of close-lying multiplets and line widths of individual signals, vdll not be altered by zero-filling. 

Spin probes are quite readily metabolized reductively by cells and have been utilized to monitor metabolic activity (lannore etal., 1990) The line widths of the e.s.r. signals are also sensitive to the presence of O2 in both intracellular and extracellular environments and hence O2 concentrations may be determined with TBN or alternative spin probes (Glockner and Swartz, 1991). 

Fig. 2.2 Intensity distribution /( ) for the emission of y-rays with mean transition energy Eq. The Heisenberg natural line width of the distribution, F = S/t, is determined by the mean lifetime T of the excited state (e)...

Fig. 2.8 (a) Fractional absorption of a Mossbauer absorption line as function of the effective absorber thickness t. (b) The depth of the spectrum is determined by fs. The width for thin absorbers, t 1, is twice the natural line width F of the separate emission and absorption lines (see (2.30)). AE is the shift of the absorption line relative to the emission line due to chemical influence... 

Nuclear resonance absorption for the 136 keV transition has been established by Steiner et al. [174]. The authors used a metal source and an absorber of metallic tantalum to determine the mean lifetime of the 136 keV level from the experimental line width ( 52.5 mm s for zero effective absorber thickness) and found a value of 55 ps. This has been the only report so far on the use of the 136 keV excited state of Ta for Mossbauer experiments. 

There is a second relaxation process, called spin-spin (or transverse) relaxation, at a rate controlled by the spin-spin relaxation time T2. It governs the evolution of the xy magnetisation toward its equilibrium value, which is zero. In the fluid state with fast motion and extreme narrowing 7) and T2 are equal in the solid state with slow motion and full line broadening T2 becomes much shorter than 7). The so-called 180° pulse which inverts the spin population present immediately prior to the pulse is important for the accurate determination of T and the true T2 value. The spin-spin relaxation time calculated from the experimental line widths is called T2 the ideal NMR line shape is Lorentzian and its FWHH is controlled by T2. Unlike chemical shifts and spin-spin coupling constants, relaxation times are not directly related to molecular structure, but depend on molecular mobility. 

Sensitivity of chemical shift analysis is determined by the spectral resolution of the XPS system. The resolution of a typical XPS system without a monochromator is 1.0 eV. This corresponds to the intrinsic line width of Al Ka or Mg Ka radiation. The analysing system contributes only little to the overall resolution. This resolution is sufficient to determine the binding energies of most core levels within 0.1 eV. Considerable improvement of the resolution down to 0.3 eV can be achieved by use of a monochromator. The higher resolution has to be paid for by a loss in intensity which, however, is no problem in modern instruments. 

Resulting 13C NMR line width l/nT2c caused by such motions can be dominantly determined by the following second or third terms, instead of the first static component,28... 

The 9Be NMR spectroscopy has been used in determination of the chiral binaphthyldiimine Be(II) complex [49].118 The measured 8Be value of 4.84 ppm and the line width of 40 Hz indicated the presence of a four-coordinate complex. The calculated 9Be NMR parameters were in good agreement with experimental results. 

The fraction may be written as the function f(Ht — H, AH), where Hr is the resonance field, or center of the individual line. It should be pointed out that the resonance field is itself a function of orientation. Perhaps this concept can best be clarified by the illustration in Fig. 12. We are trying to determine the total energy absorption at the magnetic field H. One radical, oriented so that its absorption is centered at HIlt contributes to the absorption at H. It is clear that the extent of the contribution depends upon the value of Hr — H and upon the line width AH. Another orientation, corresponding to resonance at Hti, contributes less while a third orientation, with resonance at HT contributes a negligible amount at H. 

To understand the molecular mechanism of phototropism it is essential to know whether adaptation is localized in a defined region of the cell or whether it is spread throughout the cell. To determine this Delbriick and Vaiju (1961) performed a series of experiments in which they stimulated the sporangiophore with ultraviolet light in sharply bounded and narrow test areas (line width of 0.2 mm). They found that the... 

Crystals of (TTF)[Au(C6F5)C1] have been grown by electrocrystallization [53] however, their crystal structure has not been determined. The room temperature conductivity, as measured on compacted pellets, is quite low (10-6 S cm-1). At room temperature, the EPR line width of these salts is about 10 G. This line width decreases with temperature as a result of increased spin-lattice relaxation times and a lower electrical conductivity. 

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