Vibrational specific doublets

Figure 1.3 Vibrational state-specific doublets observed in the S,-S fluorescence excitation spectrum of jet-cooled TRN(OH) bySekiya et al. [31],...

Not assigned to specific vibration. Doublet between 1260 and 1315 cm Not recorded. 

The very different spectra of iodine obtained under continuum and discrete resonance-Raman conditions are illustrated in Fig. 11 for resonance with the B state, whose dissociation limit is 20,162 cm . In the case illustrated of discrete resonance-Raman scattering, Xl =514.5 nm, and specific re-emission results from an initial transition from the v" = 1 vibrational, J" = 99 rotational level of the X state to the v = 58, J = 100 level of the B state, i.e. the transition is 58 - l" R(99). Owing to the rotational selection rule for dipole radiation, AJ = 1, a pattern of doublets appears in the emission. Clearly, the continuum resonance-Raman spectrum of iodine (Xl = 488.0 nm) is very different from the discrete case spectrum. The structure, which arises from the 0,Q, and S branches of the multitude of vibration-rotation transitions occurring, can be analysed in terms of a Fortrat diagram, as done for gaseous bromine (67). 

Figure 1.7 Vibrational state-specific effective potential energy functions for the skeletal contortion vibration [86], Transitions at 754, 743.3 cm" forTRN(OH) isolated in a Ne matrix are assigned as the spectral doublet, and Aj, is the upper state splitting, ofthe v,...

As discussed in Section 8.2, superexcited states, AB, can decay by both autoionization and dissociation (more specifically, by predissociation). Decay by spontaneous fluorescence can be neglected for superexcited states because, generally, the predissociation or autoionization rates (l/rnr 1012 to 1014s-1) are much faster than the fluorescence rate (l/rr < 108s-1). Only two examples of detected spontaneous fluorescence from superexcited states have been reported (for H2, Glass-Maujean, et ai, 1987, for Li2, Chu and Wu, 1988). The H2 D1 e-symmetry component is predissociated by an L-uncoupling interaction with the B 1B+ state (see Section 7.9 and Fig. 7.27). Since a 4E+ state has no /-symmetry levels, the /-components of the D1 A-doublets cannot interact with the B E+ state and are not predissociated. The v = 8 level of the D1 state, which lies just above the H/ X2E+ v+ = 0 ionization threshold, could in principle be autoionized (both e and / components) by the X2E+ v+ = 0 en continuum. However, the Av = 1 propensity rule for vibrational autoionization implies that the v = 8 level will be only weakly autoionized. Consequently, the nonradiative decay rate, 1 /rnr, is slow only for the /-symmetry component of the D1 v = 8 state. Thus, in the LIF spectrum of the D1] —... 

Fourier-transform infrared (FTIR) spectroscopy is an invaluable characterization technique used to confirm the chemical structure of a polymer, particularly through the observation of vibrational transitions associated with specific functional groups [185,186]. The technique has been extensively used for the characterization of polymer blends and several reviews have appeared in the literature [187-190]. FTIR measurements can help identify the mechanism of interaction between the components of a polymer blend. For example, FTIR studies carried out by Hsu and coworkers [191] have shown that the favorable interaction between PS and PVME can be monitored through the C—H out-of-plane vibration of the phenyl ring at 698 cm in PS and the COCH3 vibration of PVME (doublet at 1085 and 1107 cm ). Changes in the position and intensity of the IR bands can be used to monitor changes in miscibility behavior ]192, 193]. 

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