10,022 research outputs found
Geometry-induced pulse instability in microdesigned catalysts: the effect of boundary curvature
We explore the effect of boundary curvature on the instability of reactive
pulses in the catalytic oxidation of CO on microdesigned Pt catalysts. Using
ring-shaped domains of various radii, we find that the pulses disappear
(decollate from the inert boundary) at a turning point bifurcation, and trace
this boundary in both physical and geometrical parameter space. These
computations corroborate experimental observations of pulse decollation.Comment: submitted to Phys. Rev.
Enhancement of surface activity in CO oxidation on Pt(110) through spatiotemporal laser actuation
We explore the effect of spatiotemporally varying substrate temperature
profiles on the dynamics and resulting reaction rate enhancement for the
catalytic oxidation of CO on Pt(110). The catalytic surface is "addressed" by a
focused laser beam whose motion is computer-controlled. The averaged reaction
rate is observed to undergo a characteristic maximum as a function of the speed
of this moving laser spot. Experiments as well as modelling are used to explore
and rationalize the existence of such an optimal laser speed.Comment: 9 pages, 12 figures, submitted to Phys. Rev.
RETRACTED ARTICLE: Fixed point theorems for solutions of the stationary Schrödinger equation on cones
Cooling of a mirror in cavity optomechanics with a chirped pulse
We investigate the response of a harmonically confined mirror to an optical
pulse in cavity optomechanics. We show that when the pulsed coupling strength
takes the form of a chirped pulse, thermal fluctuations of the mirror can be
significantly transferred to the cavity field. In addition, the frequency
modulation of the pulse could enable a better cooling performance by
suppressing the sensitivity of the dependence of detuning and pulse areas.
Using numerical investigations, we find that the pulsed-cooling is mainly
limited by the cavity-field decay rate.Comment: 6 pages, 4 figure
Guiding chemical pulses through geometry: Y-junctions
We study computationally and experimentally the propagation of chemical
pulses in complex geometries.The reaction of interest, CO oxidation, takes
place on single crystal Pt(110) surfaces that are microlithographically
patterned; they are also addressable through a focused laser beam, manipulated
through galvanometer mirrors, capable of locally altering the crystal
temperature and thus affecting pulse propagation. We focus on sudden changes in
the domain shape (corners in a Y-junction geometry) that can affect the pulse
dynamics; we also show how brief, localized temperature perturbations can be
used to control reactive pulse propagation.The computational results are
corroborated through experimental studies in which the pulses are visualized
using Reflection Anisotropy Microscopy.Comment: submitted to Phys. Rev.
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