FWHH, full width at half height

FIGURE 4.4 Line shapes. Lorentzian (broken lines) and Gaussian (solid lines) line shapes and their first derivatives are given. The outermost vertical lines delimit full width at half height (FWHH) of the absorption lines. 

FIGURE 9.1 Linewidth versus standard deviation. A gaussian distribution of unit amplitude is plotted on an x-axis scale in units of the standard deviation (or sigma). At 3.15x0 the unit intensity has dropped to 0.1%. The linewidth in simulations is usually expressed as the halfwidth at half height (HWHH), which is equal to circa 1.17x0, or as twice this value that is, the full width at half height (FWHH). 

For a le couple, the Nemstian behavior predicts a peak full width at half-height (FWHH) of 90.6 mV. Real peak FWHH usually differs from that value. This... 

To further characterize the mobility of the IRE loop, time-resolved isotropic fluorescence emission decay components of the IRE RNAs were determined as a function of temperature. Some details of the measurements and data assessment will be necessary here to appreciate both the utility of the information and caveats about its literal interpretation. Considering first the TCSPC instrument itself, some uncertainty in the measurements arise from its intrinsic parameters. With 300 nm incident light, the IRF of the photomultiplier tube ranged from 190 to 276 ps full-width at half-height (FWHH). The width of the IRF and the time resolution (32.5 ps/channel) limit the short components that can be reliably extracted from the fit, and certainly those <200 ps will have large errors on their amplitudes and lifetimes. Fluorescence emission decay components as short as 9—20 ps (Larsen et al., 2001) and 30—70 ps (Guest el al., 1991) (and much shorter by Wan et al., 2000) have been measured for 2AP in a stacked conformation, but in our instrument, a fit to such a short lifetime would be inaccurate. 

FIGURE 12.14 (a) Plot of the wave number and bandwidth (full width at half height) of the C-C raman peaks for different SiC fibers after various thermal treatment in air or in nonoxidizing atmospheres, (b) Comparison between ultimate tensile strength and sp peak FWHH as a function of thermal treatment for SiC Hi Nicalon fibers. (Adapted from Colomban, P., Raman microscopy and imaging of ceramic fibers in CMCs and MMCs, Ceramic Trans., 103, 517, 2000. With permission.)... 

Figure 5 shows the results for model T. The calculated spectra were obtained from Gaussian convolution applied to the election transition probabilities Irom the Ni Is orbital with a full-width at half-height (FWHH) of 1.0 eV. The energy scale for the ceilculated spectra was calibrated by assigning the calculated Is —> 3d transition to the energy of the pre-edge peak in the each recorded XANES spectra. The calculated spectra have three peaks, which however, have a poor fit to the observed one at the positions arrowed, especially, the point II. 

The following dehydroxylation stage, between 460 and 645 °C, can be interpreted by the condensation of about 0.3 OH per square nanometer absorbing around 3680 cm-1 (full width at half height (fwhh) 180 cm-1), internal silanols excluded, and of nearly the same number with t/OH 3736 cm-1 (fwhh 20 cm-1) (26). Although not firmly proved, a condensation as pairs of weakly proton donor and acceptor hydroxyls is suggested ... 

The spectriun of D2 on NagCa2-A and Na4Ca4-A showed weak overtone bands at about 5760 cm Frequency shifts versus the frequency of the fimdamental stretching mode in the gaseous state, Vg, and full-width at half-height (FWHH) exhibited values roughly twice as large as those shown by the fundamental vibration bands [605]. From the overtone spectra the authors, therefore, concluded that... 

For a number of bent triatomic molecules (SO2, H2S, D2S, H2O) as well as linear ones (N2O, CO2), Foerster and Schuldt [654] foimd an interesting relationship between the band shape (full-width at half-height, FWHH or AVi/2) and the respective band shifts, Av. In the case of the V3 modes, a linear correlation was observed between the absolute value of the shifts, Av and the widths, AVi/2 (cf. also [620]). 

The ILS not only distorts the true bandshape in terms of the "feet", but the magnitude of L determines the width of the ILS. It can be shown that the full width at half height (FWHH) for a sine function is 1.21/L. Consequently as L becomes greater, the ILS becomes narrower and the resolution of the spectrum increases, but is of course limited to the inherent sample resolution. 

Peak asymmetries cause problems in measuring accurate chemical shifts values. The broadness, low signal-to-noise ratio and asynunetries make difficult the quantitative analysis. Reliable information can be obtained by lines fitting using Gaussian functions and take into consideration of full width at half-height (fwhh). These considerations reduce the error of the DA calculation specially arising from low value of the DA (Heux et al. 2000). 

FWHH, FWHM Full-width at half-height/maximum... 

Table 4. Fundamental and overtone frequencies, full-widths at half-height (fwhh), vibrational constants (in cm and dissociation energies De (in eV) of homonuclear diatomics adsorbed in zeolites and compared with the gasphase data.

Since the approximate full-width at half-height (FWHH) of each pulse is 100 fs, the distance occupied by each pulse is about 30 pm. The spectra shown in Figure 12.16 are measured at a resolution of 6 cm , which means that the maximum optical path difference for the interferometer is 0.17 cm or 1700 pm. The water vapor absorption that is evident in Figure 12.14 indicates that the... 

No matter what type of spectrometer is used, a measured spectrum is always slightly different from the true spectrum because of the measurement process, and it is important to recognize that instrumental effects often determine how well Beer s law is obeyed for any chemical system. For example, when a monochromator is used to measure a spectrum, the true spectrum is convolved with the spectrometer s slit function. The effect of this convolution is to decrease the intensity and increase the width of all bands in the spectrum. The convolution of Lorentzian absorption bands with a triangular slit function was reported over 50 years ago in a classic paper by Ramsay [1]. Ramsay defined a resolution parameter, p, as the ratio of the full width at half-height (FWHH) of the slit function to the true FWHH of the band. He showed how the measured, or apparent, absorbance, A, at the peak of a Lorentzian band varied as a function of the true peak absorbance, peak> resolution parameter. Not surprisingly, Ramsay showed that as... 

In contrast to the spectral definition of a few Hz or less achievable in the liquid state NMR spectrum of a polymer, the spectrum of a polymer solid (e.g., glassy or crystalline materials) usually consists of a single broad resonance line having a full-width at half-height (FWHH) of tens of KHz. However, this result does not imply that a solid spectrum is devoid of information. 

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