Shape resonances molecular fields

The shape resonances have been described by Feshbach in elastic scattering cross-section for the processes of neutron capture and nuclear fission [7] in the cloudy crystal ball model of nuclear reactions. These scattering theory is dealing with configuration interaction in multi-channel processes involving states with different spatial locations. Therefore these resonances can be called also Feshbach shape resonances. These resonances are a clear well established manifestation of the non locality of quantum mechanics and appear in many fields of physics and chemistry [8,192] such as the molecular association and dissociation processes. 

This beautiful empirical evidence had a strong stimulating effect In the study of shape resonances In molecular photolon-Izatlon, Just as early observations of the Xg shape resonance In elastic e-No scattering did In the electron-molecule scattering field (3,17). 

In sunutary, we have used prototype studies on N2 to convey the progress made in the study of shape resonances in molecular fields, particularly in molecular photoionization. This Included the identification of shape resonant features in photoionization spectra of molecules and the accrual of substantial physical insight into their properties, many of which are peculiar to molecular fields. 

The DCS is a rich source of information about atomic and molecular interactions as it allows one to unfold the partial wave averaging and analyze each /-contribution separately [43]. In addition, spin relaxation cross-sections are extremely sensitive to the atom-molecule interaction potential [19]. Therefore, we expect the spin relaxation DCS to be a sensitive probe of the anisofropic molecular interactions. As shown in Section 4.2, electric fields enhance the / / 1 transitions, and thus the sensitivity of the cross-sections to the anisotropic part of the interaction potential. Figure 4.20 illustrates that spin relaxation DCSs assume a specific 0 dependence near a shape resonance, which can be used for detection and assignment of shape resonances in cold collisions. 

For the investigation of the molecular dynamics in polymers, deuteron solid-state nuclear magnetic resonance (2D-NMR) spectroscopy has been shown to be a powerful method [1]. In the field of viscoelastic polymers, segmental dynamics of poly(urethanes) has been studied intensively by 2D-NMR [78, 79]. In addition to ID NMR spectroscopy, 2D NMR exchange spectroscopy was used to extend the time scale of molecular dynamics up to the order of milliseconds or even seconds. In combination with line-shape simulation, this technique allows one to obtain correlation times and correlation-time distributions of the molecular mobility as well as detailed information about the geometry of the motional process [1]. 

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