Intensity and Band Shape

The standard infra-red methods are clearly inadequate for poly-isoprene. The determination of relative amounts of cis and trans structures in particular is subject to large errors (113) as the infra-red bands are virtually coincident and differ only in band shape and intensity. The N. M. R. method of analysis (16) is more satisfactory, particularly for determination of the cis/trans ratio1. As can be seen from the table the results are often widely different from those obtained by infra-red analysis. 

Ligand-to-Metal Charge-Transfer (LMCT) Band Shapes and Intensities... 

In the remainder of this chapter we briefly consider the application of band shape and intensity criteria in the assignment of PE bands to molecular states. The assignment of the spectra of small molecules is very often aided by a considerable fine structure as exemplified by the PE spectrum of CS in Fig. 4. Indeed, the vibrational structure of the PE spectra of small species like CS and HjCS has been calculated yielding a rather striking match of the experimental spectra and thereby confirming the assignment based on the energy criterion. Also qualitative... 

The application of band shape and intensity criteria is of course greatly facilitated when the individual PE bands are well separated and show fine structure. The... 

Infra red beam can be resolved into polarized components in which the electric vector oscillation is parallel and perpendicular to the plane of incidence, respectively. When one polarized component hits a metal surface, a stationary wave is generated, resulting from the interference between incident and reflected beams. The spectral band features in IRRAS mode, peak positions, band shapes and intensities will considerably differ from the transmission spectra of the material. In IRRAS spectra, if the film thickness is thin enough in comparison to the wavelength of the incident IR light, the normalized reflectivity change increases in proportion to the film thickness d (up to nanometer dimension) and quantitative information on the thickness can be obtained [8]. 

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