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In numerous state-to-state dynamics studies of atom transfer reactions at energies substantially in excess of the barrier height, population is not observed in many of the energetically accessible product quantum states. Frequently, the experimental state distributions end for internal energies well below the total energy limit. The lack of observable population in these high energy states has led us to conclude that not all of the total available energy is accessible to the rovibrational states of the products. To explain this behavior we describe a model in which the internal energy is constrained by kinematic factors. We use this model to show that the energy constraint is quantitatively determined by the skew angle for the reaction. We apply this model to the results of state-to-state experiments on a large number of reactions and get quantitative agreement between our predictions and actual observations.

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Simulations were performed to assess the prospective performance of a 16 Kbit nanowire-based electronic nanomemory system. Commercial off-the-shelf microcomputer system modeling software was applied to evaluate the operation of an ultra-dense storage array. This array consists of demonstrated experimental non-volatile nanowire diode switches, plus encoder-decoder structures consisting of demonstrated experimental nanowire-based nanotransistors, with nanowire interconnects among all the switching devices. The results of these simulations suggest that a nanomemory of this type can be operated successfully at a density of 10(11) bits/cm(2). Furthermore, modest device alterations and system design alternatives are suggested that might improve the performance and the scalability of the nanomemory array. These simulations represent early steps toward the development of a simulation-based methodology to guide nanoelectronic system design in a manner analogous to the way such methodologies are used to guide microelectronic system design in the silicon industry.

Resonance enhanced multiphoton ionization of the hydrogen halides: Rotational structure and anomalies in Rydberg and ion-pair states of HCl and HBrThe rovibrational state distributions for the HCl product of the 193 nm photodissociation of (HCl) 2 , (HCl) 2 ϩh→HϩClϩHCl, have been measured. The HCl dimer is prepared in a supersonic expansion of HCl in Ar, and its photoproduct detected by resonant multiphoton ionization under collisionless conditions. The state distributions are extremely ''cold,'' with very little of the available energy deposited in either rotation or vibration of the surviving HCl molecule. Only vЈ ϭ0 product is observed, and linear rotational surprisal analysis yields an extremely large surprisal parameter, r Ј of 95͑8͒. The results are in excellent agreement with theoretical predictions.