The unimolecular reaction of a vibrationally excited molecule having low rotational excitation often leads to nascent products in which the vibrational degrees of freedom appear ‘‘hotter’’ than the rotation, translation (R,T) degrees of freedom. We show that this can derive from parent vibrations being ‘‘hot’’ while parent rotations remain ‘‘cold,’’ since the parentage of product vibration is parent vibration, while product R,T excitations are obtained from parent vibration as well as rotation. Calculations are performed for reactions having loose transition states and no reverse barriers, in which an ensemble of 3N–6 degrees of freedom are used to equilibrate parent vibrations, thereby providing a statistical distribution of product vibrational excitations. For each set of product vibrational states, all R,T excitations are then apportioned statistically using the phase space theory of unimolecular reactions (PST). The results indicate that for those energies above reaction threshold (E‡) which exceed the lowest product vibrational energies, product vibrations are more excited than with PST, while product R,T excitations are less than with PST. These differences increase with E‡, and rotational distributions obtained using the separate statistical ensembles (SSE) method peak at low N″ relative to PST. When product vibrations are energetically inaccessible, SSE and PST are identical. The calculations are compared to nascent distributions from the unimolecular dissociation of monoenergetic NCNO, and the agreement is excellent.

Single and multilayer graphene films offer the potential for significant weight reduction in lithium-ion batteries for next-generation power systems, including microbatteries. When scaling down Li-ion battery size and weight, it is important to understand the impact of reducing the number of graphene layers on electrochemical performance. We compared the electrochemical performance of anodes fabricated from pristine single layer graphene (SLG), few layers of multilayer graphene (MLG), and several thousand layers of highly oriented pyrolytic graphite (HOPG). Coin-cell anodes were fabricated without a binder from graphene films grown directly on copper and nickel foils. Cycling at 5 μA/cm 2 indicated reversible capacities of ∼0.047 and 0.040 mAh/cm 2 for SLG-Cu and MLG-Ni. Subtracting substrate contribution and normalizing to the mass of the graphene layer(s), the specific capacities for SLG and MLG are high (13263 mAh/g and 1185 mAh/g). Distinct peaks were observed in cyclic voltammograms of MLG indicating lithium intercalation into the graphene layers, but not in SLG, suggesting a different mechanism for lithium storage. XPS results of charged SLG-Cu suggest that the reversible charge is present both on top of the SLG and between SLG and Cu. The performance of HOPG was poor (23 mAh/g) and appears to be Li-diffusion limited.

The 193 nm excitation of the CO2 ⋅ HBr van der Waals complex causes HBr to dissociate rapidly, thereby promoting the endothermic reaction of atomic hydrogen with the adjacent CO2. The reactants are highly oriented by the CO2 ⋅ HBr equilibrium geometry.

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