Spectra, polarized band assignments

Below 625 nm the reported absorption spectra consist of a series of intense LMCT excitations and their marked polarization dependence allows an unambiguous band assignment. In the red and near-IR region of the spectrum the highly structured d-d transitions are of low intensity. The vibrational progressions that are observed in the absorption and in the lumines-... 

In the Raman spectrum of f-butyllithium-7, only the strongly polarized band at 521 cm shifts significantly upon Li substitution (563 cm ) (Table 2). It was assigned to a totally symmetrical C—Li stretching mode. The peak at 525 cm in the IR spectrum was attributed to an impurity, because it exhibited widely variable intensity in various determinations and disappeared in one spectrum. ... 

The picosecond IR absorption spectrum of the tS state in the fingerprint region is different in w-heptane and in acetonitrile. The spectrum recorded for Si tS in the nonpolar solvent w-heptane is consistent with a species that has a center of symmetry. In acetonitrile, the spectrum exhibits additional weak bands near 1570, 1250, and 1180 cm which are approximately at the same frequencies as strong Raman bands assigned to in-plane vinylic vibrational modes in 5i. This result was taken to suggest a molecular structure for 5i that lacks a center of symmetry in acetonitrile. However, because the intensities of these three bands are weak, it was concluded that either the polarization of 5i or the contribution from polarized S structures to all of the S structures in acetonitrile may be small. 

Chandross, Longworth, and Visco126 have reported the observation of long-wave structureless emission bands in the vicinity of the electrodes during the ac electrolysis of anthracene, phenanthrene, perylene, and 3,4-benzpyrene in polar solvents such as acetonitrile and dimethylformamide the similarity between the perylene band and the crystal fluorescence spectrum prompted the assignment of these bands to excimer fluorescence originating in the process... 

In the case of naphthalene, transitions to the two lowest excited states (again, often indicated with Lb and La) are two-photon forbidden, as in benzene. However, due to vibronic coupling, the Lb band is visible in the 2PA spectrum of naphthalene in the 575-650 nm region (see Fig. 5), while La gains intensity in the IPA spectrum and peaks around 275 nm [44-46], but is basically absent from the 2PA spectrum this is again in line with predictions based on the pseudoparity of the states. Polarization ratio data were used to aid the band assignment. A weak 0-0 peak of the Lb band can actually be seen in the 2PA spectrum (at 630.5 nm for naphthalene in cyclohexane [45] and at 631.8 nm in carbon tetrachloride [47]), probably because of local perturbation of the symmetry due to the solvent environment or other effects [44,45]. The 2PA... 

The Raman spectrum of Hg3 + (AsF0)2 in sulfur dioxide solution shows in addition to peaks attributable to AsFg and the solvent, a single strong polarized band at 118 cm which was assigned to a Hg-Hg stretch indicating that Hgg has the linear structure Hg" -Hg-Hg +. ... 

Two intense sharp and strongly polarized bands at 1074 and 572 cm" in the Raman spectrum of gaseous N2F4 at 250°C (Kr laser excitation at 647.1 nm), which are absent in the room temperature spectrum, were assigned to the symmetric stretching (v ) and bending (vg) fundamentals of NFg, respectively. 

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