Biomedical subjects

S J Putterman

Publications and source records attributed to S J Putterman.

4 recordsLinked to original sources

PubMed2002

Blackbody spectra for sonoluminescing hydrogen bubbles.

The dynamical motion of sonoluminescing bubbles formed from a mixture of water and hydrogen gas indicates that these bubbles contain hydrogen. Their spectrum is well matched by an ideal 6000 K blackbody radiating from a surface with a radius less than 1/4 microm. According to this model, the state of matter inside the collapsed bubble is so stressed that the photon mean free path is much smaller than 1 microm. Implications for various theories of the light-emitting mechanism and the role of chemical reactions are discussed.

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PubMed2001

Comment on "Mie scattering from a sonoluminescing bubble with high spatial and temporal resolution".

A key parameter underlying the existence of sonoluminescence (or SL) is the time dependence of the radius R(t) of the collapsing bubble from which SL originates. With regard to the use of light scattering to measure this quantity, we wish to note that we disagree with the statement of Gompf and Pecha-highly compressed water causes the minimum in scattered light to occur 700 ps before SL-and that this effect leads to an overestimate of the bubble wall velocity. We discuss potential artifacts in their experimental arrangement and reply to their criticisms of our experiments on Mie scattering.

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PubMed2000

Observation of bubble dynamics within luminescent cavitation clouds: Sonoluminescence at the nano-scale.

Measurements of acoustically driven cavitation luminescence indicate that this phenomenon is robust over a huge parameter space ranging from 10 kHz to >10 MHz. The minimum bubble radius achieved is an upper bound for the size of the light-emitting region and ranges from about 1 microm at 15 kHz to tens of nm at 11 MHz. Although lines can be discerned in the spectra of some cavitation clouds, they sit on top of a broadband continuum which can have greater spectral density in the ultraviolet than is observed for resonantly driven sonoluminescence from a single bubble.

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PubMed2000

Temperature and pressure dependence of sonoluminescence.

The dependence of sonoluminescence on ambient pressure and temperature is measured. As water is cooled, there occurs a 100-fold increase in light emission which can be accompanied by only slight changes in the ambient radius of the pulsating bubble. This suggests that water vapor trapped in the collapsing bubble is a key parameter for this system. For fixed concentration of gases in water, the maximum intensity of sonoluminescence decreases as the ambient pressure is lowered below 1 atm.

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