Transformations molecules, transition probabilities

Calculated Transition Probabilities W00 for the Transformation 14C -> 14N in Singly Replaced Organic Molecules"... 

In such cases, the linewidth of a Doppler-free molecular transition is no longer limited by the spontaneous transition probabilities (Sect. 3.1), but by the time of flight through the laser beam, which determines the interaction time of the molecule with the radiation field. This can be seen as follows consider an undamped oscillator x = xq cos co )t that oscillates with constant amplitude during the time interval T and then suddenly stops oscillating. Its frequency spectrum is obtained from the Fourier transform... 

The study of the rearrangement of molecular orbitals under the transformation T -> He+ allows one to understand qualitatively the relation between the excitation spectrum of the daughter ion and the features of its chemical structure. If the MOs of the daughter and the parent molecules coincided, the probability [Eq. (44)] of transition into the ground state would be unity, and the excitation probability would be zero. In the sudden-perturbation approximation, it is to the difference in the orbitals of the initial and the final molecules that the excitation of the latter is due. 

More frequently than chemical techniques, the spectroscopic methods of analysis are used for the determination of polymer chemical composition. Among these techniques the use of infrared (IR) absorption spectra as fingerprints for polymer identification is probably the most common. The IR absorption is produced tjy the transition of the molecules from one vibrational quantum state into another, and most polymers generate characteristic spectra. Large databases containing polymer spectra (typically obtained using Fourier transform infra-red spectroscopy or FTIR) are available, and modern instruments have efficient search routines for polymer identification based on matching an unknown spectrum with those from the library. For specific polymers, the IR spectra can reveal even some subtle composition characteristics such as interactions between polymer molecules in polymeric blends. 

The complex with [Li+]/[PO] = 0.10 exhibits a crystalline melting transition followed by a smectic A mesophase. By increasing the salt concentration as in the case of complexes with [Li+]/[PO] = 0.15 0.30, the smectic A phase is suppressed instead, they exhibit a hexagonal columnar mesophase as evidenced by X-ray scattering. The induction of ordered structure in the melt state of the rod—coil molecule by complexation is most probably due to enhanced microphase separation between hydrophobic blocks and polypropylene oxide) block caused by transformation from a dipolar medium to an ionic medium in polypropylene oxide) coil. 

The structure of pSs (space group Plilc-C2 p, Table 7) consists of crownshaped Ss rings with approximate 04a symmetry in two kinds of positions. Two thirds of the rings form the ordered skeleton of the crystal while the other molecules are disordered on pseudocentric sites. The disorder is twofold, a rotation of the molecules on disordered sites by 45 around the principal axis transforms the molecule in its alternate position (Fig. 7). The probability of each position is 50% well above the transition temperature of 198 K (see below). 

---