FWHM, spectral full-width

The spectral width of the fluorescence contour also gives insight into the immediate environment about the probe. Figure 6 shows that the spectral full-width-at-half maximum (FWHM) is initially wide at low density, goes through intermediate values as density is increased, and levels off at higher densities. These results are... 

Figure 6. Influence of density on the spectral full-width-at-half maximum (FWHM) for 10 pM PRODAN in supercritical CF3H.

Reflection holograms were recorded at 514 nm at 0 incidence with a mirror laminated to the back of the film, UV cured, and heated. These results show that baking a UV-cured hologram raises the hologram s peak optical density substantially, along with the spectral full-width half maximum (FWHM), and An. 

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. 

To introduce the application of ultrashort laser sources in microscopy, we want to review some properties of femtosecond pulses first for a comprehensive introduction the reader may refer to one of the established textbooks on femtosecond lasers (Diels and Rudolph 2006). The most important notion is the Fourier transform relation between the temporal shape of a pulse and the spectrum necessary to create it. This leads to the well-known time-bandwidth product for the pulse temporal width (measured as full width at half maximum, FWHM) At and the pulse spectral width Av. 

Table 1. Spectral position (co) of peak, full-width (Ar) at half-maximum (FWHM) intensity of G+ band, normalized intensity ratio of SWNT with pyrene/naphthalene to SWNT (IgVIg+) /(Ig+/Ig4 and parameter of BWF curve (1/q) obtained with laser excitation at =632.8 nm.

H-bonded systems may require additional diffuse or polarization functions. For example, the 6-311++G(d,p) basis set had been found to be suitable for H-bonded systems [78-81], It may be necessary to include Basis Set Superposition Errors (BSSE) [82] and Zero-Point-Energy (ZPE) corrections in evaluating the relative stabilities. Such corrections are often of the same magnitude as the energy differences among the dominant conformers. Moreover, the relative conformer energies may also differ noticeably with the basis sets used. All these factors will affect the Boltzmann factors predicted for different conformers and therefore the appearance of the population weighted VA and VCD spectra. Thus, an appropriate selection of DFT functionals and basis sets is very important for VCD simulations. A scale factor of 0.97-0.98 is usually applied to the calculated harmonic frequencies to account for the fact that the observed frequencies arise from an anharmonic force field instead of a harmonic one. A Lorentzian line shape is typically used in simulations of VA and VCD spectra. The full-width at half maximum (FWHM) used in the spectral simulation is usually based on the experimental VA line widths. 

There are experimental evidence for the assignment of Sj to the ttct state for both HFB and PFB. Figure 15-33(a) presents the fluorescence excitation and dispersed fluorescence spectra of HFB in supersonic free jet [74], The fluorescence excitation spectra very closely mimic the vapor-phase irir S0 absorption spectra of the compound. It is evident that there is no spectral overlap between the fluorescence and the tht <- S0 absorption spectra of HFB. The energy difference between the absorption and emission maxima is greater than 11 000 cm-1. Moreover, the full width at half maximum (FWHM) of the absorption is about 3000 cm-1, whereas that of the dispersed emission is about 5500 cm-1. For fluorinated benzenes with four or less F atoms, the absorption and emission bands overlap with the Stokes shift of about 4000 cm-1, and the FWHM of both bands is about 3000 cm-1. The FWHM absorption bandwidth of 3000 cm-1 is characteristic of tht (Lft) S0... 

Half-width [of a band) The full width of a spectral band at a height equal to half of the height at the band maximum. Also known as full width at half maximum (FWHM). The dimension of band width should be either inverse length wave-numbers) or inverse time (frequencies) so that the values give an indication of the energies. Note the hyphen in half-width. Half bandwidth has the meaning of half-width at half maximum. 

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