Lower-energy regions

The range covered by these spectral measurements was not indicated but in the lower energy region further weak bands due to the 2T2g 4T ig... 

In contrast to infrared spectrometry there is no decrease in relative sensitivity in the lower energy region of the spectrum, and since no solvent is required, no part of the spectrum contains solvent absorptions. Oil samples contaminated with sand, sediment, and other solid substances have been analysed directly, after being placed between 0.5 mm 23-reflection crystals. Crude oils, which were relatively uncontaminated and needed less sensitivity, were smeared on a 2 mm 5-reflection crystal. The technique has been used to differentiate between crude oils from natural marine seepage, and accidental leaks from a drilling platform. The technique overcomes some of the faults of infrared spectroscopy, but is still affected by weathering and contamination of samples by other organic matter. The absorption bands shown in Table 9.1 are important in petroleum product identification. 

There are no experimental data of excitation cross sections for proton and alpha particle impact for water. The proton cross sections were obtained by scaling of the electron excitation cross sections for high-energy protons >500 keV [201]. For the lower-energy regions, the semiempirical model developed by Miller and Green [202] was adopted, which is based on the electron impact excitation. They assumed an analytical function for each excited level of the form... 

The authors finish by exploring the transferability of their force field parameters to a different zeolite, namely, silicalite. In this instance, a Fourier transform of the total dipole correlation function provides another model infrared (IR) spectrum for comparison to experiment, and again excellent agreement is obtained. Dominant computed bands appear at 1099, 806, 545, and464 cm while experimental bands are observed at 1100, 800,550, and 420 cm A Some errors in band intensity are observed in the lower energy region of tlie spectrum. 

Figure 2.7 Sedimentary facies in three general zones of the Ogeechee River/Ossabaw Sound estuary (USA). Fine-grained sediments predominate in the lower-energy region (stations 2, 3, and 4) as opposed to the high-energy point bars (station 5) and mouth (1) which have a higher abundance of coarse-grained sediments. (Modified from Howard et al., 1975.)...

The energy region lower than (2). Lower energy region. 

It is also observed that, for a given pressure, the ratio of fluorescence to phosphorescence remains constant for at least the lower-energy region of the band (Aex - 313 nm). This suggests that fluorescence and intersystem crossing occur from the same levels of the excited singlet state. The absorption spectra, emission spectra, and quantum yields of fluorescence of linear aldehydes have been summarized recently (102). 

It should be pointed out, however, that the true magnitude of Vei for hole transfer is not exactly equal to that determined by PE spectroscopy because the latter value corresponds to the energy difference between the cation states with geometries identical to that of the neutral diene, whereas the actual path for hole transfer will almost certainly traverse a different (and lower energy) region of the avoided crossing seam that is associated with a structure which is slightly different from that of the relaxed neutral species. 

To confirm the generality of a diffuse dipole-bound excited state existing in anion clusters with polar solvent molecules, Johnson and the co-workers extended the study to I clusters solvated with acetonitrile molecules, i.e., I -(CH3CN) (n = 1 and 2) [54]. Acetonitrile was chosen as a suitable solvent, since it has no anionic valence state lying in the lower energy region and its dipole moment is large (3.92 D). 

XANES (X-ray Absorption Near-Edge Strueture) is X-ray absorption spectroscopy for the lower energy region than EXAFS (Extended X-ray Absorption Fine Structure). It is sensitive to the local atomic arrangement around the absorbing atom and to the chemical states because the low energy electrons emitted through the photoabsorption are affected by details of the molecular potential (1). 

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