Rotatory vibration

D. H. Andrews, Leiden Commun. Suppl., No. 56 (1926) also assumes the existence of rotatory vibrations of large molecules in the fixed lattice in his explanation of specific heats (see also E. Schrodinger, Handbuch der Pfiysik, 10, 314, note 2). 

The conclusion reached is that chemical reactions are closely related to molecular motion and structures, where molecular conformation and molecular orientation are important parameters. We have discussed whether the hydrogen abstraction reaction of peroxy radicals in the inner crystalline region of polypropylene is due to then-abstraction of the hydrogen from the intra-chain segment or inter-chain one. (1) It was confirmed that the unstable and mobile radicals participated in a rotation or a rotatory vibration of the COO group around the main chain axis. (2) The conformational structure of the mobile peroxy radicals was close to a skew conformation. (3) It could be safely concluded that the mobile peroxy radicals were trapped in disordered sites in the inner crystalline region. 

Two rotatory vibrations are degenerate for X(jt,0,0), G(ji,5b.0)> U(jt, Jt, 0), A( g, 7t, 0) and Z(0, ji,0) where 5, and/or 5b = 7t. For these rotatory vibrations, (0v/0 e)o = O shown in Fig. V.4(c), (d), (e) and (f), and accordingly rotatory vibrations of the polyethylene chain give rise to a prominent peak near 150cm" . These rotatory vibrations, however, turn into internal-rotation vibrations as the phase difference is increased from = 0 to tc. Vibrational frequencies change little with and a broad shoulder is observed on the high-frequency side of the peak near 150 cm" (see Fig. V.8). 

Drehungs-grad, m. degree of rotation, -kraft, /, rotatory power, -schwingtmg, /, torsional vibration, -streuung, /, rotatory dispersion, -vermogen, n, rotatory power, -winkel, m. angle of rotation. 

The primary motivation for the development and application of vibrational optical activity lies in the enhanced stereochemical sensitivity that it provides in relation to its two parent spectroscopies, electronic optical activity and ordinary vibrational spectroscopy. Over the past 25 years, optical rotatory dispersion and more recently electronic circular dichroism have provided useful stereochemical information regarding the structure of chiral molecules and polymers in solution however, the detail provided by these spectra has been limited by the broad and diffuse nature of the spectral bands and the difficulty of accurately modeling the spectra theoretically. 

There are many more solvent effects on spectroscopic quantities, that cannot be even briefly discussed here, and more specialized works on solvent effects should be consulted. These solvent effects include effects on the line shape and particularly line width of the nuclear magnetic resonance signals and their spin-spin coupling constants, solvent effects on electron spin resonance (ESR) spectra, on circular dichroism (CD) and optical rotatory dispersion (ORD), on vibrational line shapes in both the infrared and the UV/visible spectral ranges, among others. 

It is the off-diagonal elements of (13.7) that give rise to cross polarization (S, = = S22) as well as the nonzero elements S13, S14, S23, and S24 in (13.8). That S3 and S4 should be nonzero for optically active particles follows from elementary physical reasoning optical rotatory power in a homogeneous medium causes the direction of vibration to be rotated upon transmission of linearly polarized light by the medium. However, optical activity of the bulk... 

A fascinating category of experiments can be found in Table IV. These are the use of lasers to determine thermodynamic parameters. These include calorimetry (43), enthalpies of vaporization and vaporization rates (44, 45), and heat capacities (46). Other laser experiments that can be found in Table IV include the use of CW laser spectroscopy to determine the iodine binding-energy curve (47), the study of vibrational line profiles to determine intermolecular interactions (48), two photon ionization spectrometry (49), a study of optical activity and optical rotatory dispersion (50) and the development of several experiments using blue diode lasers (57). 

OPTICAL ROTATION, OPTICAL ROTATORY DISPERSION, ELECTRONIC CIRCULAR DICHROISM, AND VIBRATIONAL CIRCULAR DICHROISM... 

Optical rotation (OR), optical rotatory dispersion (ORD), electronic circular dichroism (BCD), and vibrational circular dichroism (VCD) provide spectral information nniqne to enantiomers, allowing for the determination of absolute configuration. Recent theoretical developments in DFT, using time-dependent density fnnctional theory (TD-DFT), provide the means for computing OR, ORD, and Similar theoretical development with coupled-cluster theory,... 

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