Watt energy spectrum

Where p defines the shape of the hole energy spectrum. The relaxation time x in Equation 3 is treated as a function of temperature, nonequilibrium glassy state (5), crosslink density and applied stresses instead of as an experimental constant in the Kohlrausch-Williams-Watts function. The macroscopic (global) relaxation time x is related to that of the local state (A) by x = x = i a which results in (11)... 

FIG. 5-11 Distribution of energy in the spectrum of a Llackbody To convert microns to micrometers, multiply by unity To convert ergs per square centimeter-second-micron-K to watts per square meter, per meter, per K, multiply by 10 . ... 

A more practical but less accurate plot of the action spectrum is what I would term the pseudo-action spectrum. The primary difference between normal and pseudo-action spectra derives from how they are obtained and plotted. Normal-action spectra are plots of the effect of a constant number of photons per wavelength versus wavelength, whereas pseudo-action spectra are obtained using a constant energy input, watts/meter, per nanometer. 

The discussion of emission spectroscopy will be concluded by a description of a rather unusual application. Bay and Steiner have measured atomic hydrogen concentrations in the presence of molecular hydrogen by microwave excitation of the atomic hydrogen line spectrum. With low power fed into the gas (ca. 5 watts), there is not enough energy available for the dissociation of molecular hydrogen and subsequent excitation. Thus the measured intensities of the atomic hydrogen lines correspond to the concentrations of atoms already present in the reaction mixture. The method is curiously similar to that adopted to detect atoms and free radicals by mass spectrometry (see Section 3). 

FT-Raman spectrometers are based on detectors that detect power (watts) rather than photons. As noted in Section 2.2, the varying energy per photon across a Raman spectrum yields different relative intensities when measuring power rather than photons. For the common case of a 1064 nm laser in an FT-Raman spectrometer with a power-sensitive detector, the predicted peak ratios for cyclohexane are included in the final column of Table 10.10. 

Figure 7.3 AES spectra of an oxidized aluminum surface (a) direct spectrum of intensity versus kinetic energy of Auger electrons and (b) differential spectrum of intensity versus kinetic energy of Auger electrons. (Reproduced with permission from J.F. Watts, An Introduction to Surface Analysis by Electron Spectroscopy, Oxford University Press, Oxford. 1990 Royal Microscopy Society.)...

The units of spectral intensity appropriate to Raman data are relative photon flux per wavenumber. This is very different in shape from the more traditional lamp calibration units of Watts per nanometer (by a factor of A ). CCD cameras used in Raman instruments register an output signal level in counts, which is proportional to the photon flux at the detector, not the energy flux. Raman spectra are normally presented in terms of counts versus Raman shift, where the Raman shift is specified in wavenumber. Hence, the lamp head calibration is in terms of relative photons per wavenumber. When the instrument is intensity calibrated in these terms, the shape of a material s Raman spectrum is not only repeatable from instrument to instrument at a given excitation wavelength but also can be remarkably similar even between instruments using different excitation wavelengths. 

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