arXiv subjects
Publications and source records attributed to S. J. Putterman.
In a paper recently published in Science, Taleyarkhan et al. claimed to observe fusion from acoustic cavitation and the associated phenomenon of sonoluminescence. Although, this is a worthwhile line of investigation we explain why, in our opinion, their data neither proves nor disproves this possibility.
Data from an instrument that measures conductance, stiffness and rupture strength of junctions indicates that when two macroscopic metal surfaces are brought into contact a nanometer size junction spontaneously forms over a long time scale (~ 60 s). Furthermore, the parameters of junction rupture match the observed dynamics of stick-slip friction. This suggests that stick-slip friction has its origins in the formation and rupture of junctions that form between surfaces in contact.
A force measurement technique has been developed that utilizes a clamped fiber optic element both as a cantilever and as a highly sensitive probe of the static and dynamic displacement of a sample that is mounted near its free end. Light from a 1.5 mW superluminescent diode coupled into the fiber is used to detect displacement with 6*10/sup -13 m*Hz/sup -1/2 sensitivity for frequencies above 40 kHz. This technique has been used to study the interaction between macroscopic bodies with atomic sensitivity. Here, we report measurements of stiffness of junctions that form when two gold surfaces are brought into contact.
A key parameter underlying the existence of sonoluminescence (SL)is the time relative to SL at which acoustic energy is radiated from the collapsed bubble. Light scattering is one route to this quantity. We disagree with the statement of Gompf and Pecha that -highly compressed water causes the minimum in scattered light to occur 700ps before SL- and that this effect leads to an overestimate of the bubble wall velocity. We discuss potential artifacts in their experimental arrangement and correct their description of previous experiments on Mie scattering.