FWHM, full width at half maximum

Energy analyzers cannot be discussed without discussion of energy resolution, which is defined in two ways. Absolute resolution is defined as AE, the full width at half-maximum (FWHM) of a chosen peak. Relative resolution is defined as the ratio R of AE to the kinetic energy E of the peak energy position (usually its centroid), that is, R = AE/E. Thus absolute resolution is independent of peak position, but relative resolution can be specified only by reference to a particular kinetic energy. 

Optimum resolution, i. e. low full width at half-maximum (FWHM), is a trade-off between high count rate, i. e. low dead-time, and good spectral resolution. 

The energy resolution of an X-ray detector is experimentally defined by the full width at half maximum (FWHM) of the Mn-Ka line. The FWHM, in eV, can also be calculated by use of the relationship ... 

Figure 16. Experimental and calculated IR resonance enhanced photodissociation spectra of Fe" (CH4)3 and Fe" (CH4)4. Experimental spectra were obtained by monitoring loss of CH4. Calculated spectra are based on vibrational frequencies and intensities calculated at the B3LYP/ 6-311+G(d,p) level. Calculated frequencies are scaled by 0.96. The calculated spectra have been convoluted with a 10-cm full width at half-maximum (FWHM) Gaussian. The D2d geometries of Fe (CH4)4 are calculated to have very similar energies, and it appears that both isomers are observed in the experiment.

When the full width at half maximum (fwhm) of a Gaussian pulse is 20 fs, its frequency width is 740 cm as the fwhm. Frequency components Ql and fis are present in the pulse and are used to generate the vibrational coherence, where Ql — iis is equal to the vibration frequency ox... 

Figure 10.6 shows CL spectra of Pt4/7/2 for stabilized Pt-Co with and without COad- The CO adsorption induced both a shift in the Pt4/7/2 CL to higher binding energy and an increase in the full width at half maximum (FWHM). Such changes can be explained by surface core level (SCL) shifts of Pt4/7/2 by COad, whereas the bulk CL is not affected by COad- hi order to extract the change in SCL shift (ASCLS) by COad, we decomposed the Pt4/7/2 spectra into two components the bulk CL and SCL. It was found that the value of ASCLS decreased in the order pure Pt > stabilized Pt-Co > Pt-Ru. 

Line breadths are the fundamental quantities in this field of polymer analysis. As a consequence of the Fourier relation between structure and scattering these breadths are integral breadths, not full widths at half-maximum (FWHM). 

The electrodeposited precursor films, annealed in air at 870 °C in the presence of a TBSBCCO pellet, produce a biaxial textured Tl-1223 phase, as confirmed by an XRD pole-figure measurement. The omega and phi scans indicate full-width at half-maximum (FWHM) values of only 0.92° and 0.6°, respectively, which indicates a very high-quality film. The superconductive transition temperature of the Tl-1223 film, determined resistively, was about 110 K. Figure 7.11... 

Treating vibrational excitations in lattice systems of adsorbed molecules in terms of bound harmonic oscillators (as presented in Chapter III and also in Appendix 1) provides only a general notion of basic spectroscopic characteristics of an adsorbate, viz. spectral line frequencies and integral intensities. This approach, however, fails to account for line shapes and manipulates spectral lines as shapeless infinitely narrow and infinitely high images described by the Dirac -functions. In simplest cases, the shape of symmetric spectral lines can be characterized by their maximum positions and full width at half maximum (FWHM). These parameters are very sensitive to various perturbations and changes in temperature and can therefore provide additional evidence on the state of an adsorbate and its binding to a surface. 

Figure 4.3 Correlation between UV peak intensity (e), full width at half maximum (FWHM), and a of various poly(dialkylsilane)s and poly(alkyl(aryl)silane)s in THF at 30°C.

Theoretically, 8/lp in the resonant wavelength shift scheme is independent of resonance shape or resonant bandwidth, and should be determined merely by instrument resolution, typically less than 10 pm. However, in reality, noise can perturb resonance spectra such that accurate determination of resonant wavelength shift becomes difficult for a broad resonance curve. To enhance accuracy in detecting wavelength shift, narrower resonance is required. This is equivalent to obtaining higher-g resonance behavior. To take into account noise-included detectability of 8/lp, 8/lp can be simply described as a fraction (p) of the full width at half maximum (FWHM) bandwidth of resonance, A7.. WnM. In this fashion, optical detection limit becomes pA/.. WnMAS or p/-vl(QS). In practice, p can be chosen as a reasonable value of 0.1. In the intensity variation scheme, 87 is determined by noise from environment and photodetectors. It can reach as low as several nanowatts with care. 

In Figure 9.13c, the EL spectra of the red-light-emitting a-Si H TFT AM-PLED and PLED are shown. EL peak positions at 654 and 653 nm, and full-width-at-half-maximum (FWHM) of 101 and 105 nm were obtained, for the a-Si H TFT AM-PLED and PLED, respectively. From the obtained EL spectra, Commission Internationale de l Eclairage (CIE) color coordinates [31] were calculated for AM-PLED and PLEDs, as shown in the inset of Figure 9.13c, and were found to be (0.67, 0.33) and (0.67, 0.32), respectively. These very... 

Values in parentheses correspond to the full width at half maximum (Fwhm) for each peak. 4 Fwhm values not reported. c phbz = p-hydroxybenzoate. 

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