Transient response in absorptive bistability

Measurements of transient response are described for a system composed of multiple beams of atomic sodium passing through a high-finesse optical cavity. For switching from zero to incident laser intensities above the upper turning point of the steady-state hysteresis cycle, a delay in excess of the empty cavity filling time is observed for the time taken to reach steady state. For switching of the incident laser intensity from zero to above the upper turning point, this delay increases to up to 12 times the empty cavity filling time. The results are in qualitative agreement with earlier theoretical work based upon the mean-field theory for plane waves in absorptive bistability.     

Supercooling of the disordered vortex lattice in Bi(2)Sr(2)CaCu(2)O(8+delta)

Time-resolved local induction measurements near the vortex lattice order-disorder transition in optimally doped Bi(2)Sr(2)CaCu(2)O(8+delta) crystals show that the high-field, disordered phase can be quenched to fields as low as half the transition field. Over an important range of fields, the electrodynamical behavior of the vortex system is governed by the coexistence of ordered and disordered vortex phases in the sample. We interpret the results as supercooling of the high-field phase and the possible first-order nature of the order-disorder transition at the "second magnetization peak."     

Reactivity of anionic gold oxide clusters towards CO: experiment and theory

In this paper, we present results from our joint experimental and theoretical study of the reactivity of anionic gold oxide clusters Au_2,3O_1-4 ^- towards CO. We provide clear evidence that, although O–O bond weakening/dissociation is important to enable CO oxidation, the presence of atomic oxygen can be favorable but is not always sufficient. Furthermore, we show that with the addition of a single gold atom the reactivity channels can be changed. As a consequence, in contrast to CO oxidation in the case of anionic gold dimer oxides, association of CO or replacement of O₂ by CO become the dominant reaction channels for Au₃O_n ^-. This demonstrates the nonscalable properties of gold clusters in the size regime in which each atom counts.