Ground-state deformation

We report here our recent half-life and Pn measurements among the low-yield fission products. The Pn values for precursors around mass 100 are unusually low, which may be a manifestation of ground state deformation in this vicinity. We also describe our observations on the three new isotopes 75cu, 24 g>an(j H9ga... 

Moller et al. (1995) calculated the atomic mass excess and nuclear ground-state deformation for 8,979 nuclei from to A = 339 between the proton and neutron drip lines (see O Fig. 2.7). The calculations with the finite-range droplet model (FRDM) contain 16 mass-like and 22 other parameters. In the framework of FRDM it is possible to calculate a large number of nuclear structure properties in addition to the ground-state masses, such as even multipole ground-state deformations (s2, 4, 65), 3-decay properties, pairing quantities, odd-particle spins, Qt-decay properties, octupole properties ( 3), etc. 

Decay properties of transuranium nuclides lead to the understanding of proton excess heavy nuclei verification of the proton drip line, nuclear structure of large deformed nuclei such as octupole and hexadecapole deformation, and fission barrier heights. There are several textbooks and review articles on nuclear decay properties of transuranium nuclei (e.g., Hyde et al. 1964 Seaborg and Loveland 1985 Poenaru 1996). Theoretical nuclear models of heavy nuclei are presented by Rasmussen (1975) and the nuclear structure with a deformed single-particle model is discussed by Chasman et al. (1977). Radioactive decay properties of transuranium nuclei are tabulated in the Table of Isotopes (Firestone and Shirley 1996). Recent nuclear and decay properties of nuclei in their ground and isomeric states are compiled and evaluated by Audi et al. (1997), while the calculated atomic mass excess and nuclear ground-state deformations are tabulated by MoUer et al. (1995). 

To increase the bulk NLO effects, one first needs to optimize the molecular hyperpolarizability. Several simple models have been developed to interpret second-order responses. The equivalent field model (EIF), developed in 1975 by Oudar and Chemla [33], was one of the first attempts. It was proposed that a major portion of the second-order response in Tt-organic chromophores could be predicted from the ground-state deformation of the TT-electron distribution by appended substituents. The relation between the TT-distortion and the quadratic hyperpolarizability is given by ... 

Regarding the emission properties, AM I/Cl calculations, performed on a cluster containing three stilbene molecules separated by 4 A, show that the main lattice deformations take place on the central unit in the lowest excited state. It is therefore reasonable to assume that the wavefunction of the relaxed electron-hole pair extends at most over three interacting chains. The results further demonstrate that the weak coupling calculated between the ground state and the lowest excited state evolves in a way veiy similar to that reported for cofacial dimers. 

If the full molecular symmetry is assumed, the ground states of the cation radical of fulvalene and the anion radical of heptafulvalene are both predicted to be of symmetry by using the semiempirical open-shell SCF MO method The lowest excited states of both radicals are of symmetry and are predicted to be very close to the ground states in the framework of the Hiickel approximation these states are degenerate in both cases (Fig. 4). Therefore, it is expected that in both these radicals the ground state interacts strongly with the lowest excited state through the nuclear deformation of symmetry ( — with the result that the initially assumed molecular... 

If the initial ground-state wavefunction (/(q is nondegenerate, the first-order term (i. e., the second term) in Eq. (1) is nonzero only for the totally-symmetrical nuclear displacements (note that g, and (dH/dQi) have the same symmetry). Information about the equilibrium nuclear configuration after the symmetrical first-order deformation will be given by equating the first-order term to zero. 

The theory just presented shows how the behavior of electrons leads to bonding in the ground state of a molecule. When dislocations move to produce plastic deformation and hardness indentations, they disrupt such bonds in covalently bonded crystals. Thus bonds become anti-bonds (excited states). This requires that the idea of a hierarchy of states that is observed for atoms be extended to molecules. 

Low temperatures are required to slow down paramagnetic relaxation in order to get sharp EPR spectra. However, when a paramagnet can relax back to the ground state only slowly, then it is easy to saturate the system with microwaves, and this will lead to deformed spectra. In this chapter we consider the two key experimental parameters power (intensity of the microwaves) and temperature (of the sample) in combination with the key system parameter the spin. For a given system of spin S at a temperature T there is a single optimal value of P, which must be determined experimentally. The combined set of P, T, and S determines the complexity and the costs of EPR spectroscopy. 

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