Results 141 to 150 of about 1,812 (181)

Electron diffusion in metals studied by picosecond ultrasonics

Physical Review B, 1994
We have studied the ultrasonic pulses that are generated when a picosecond light pulse is absorbed in a metallic film. The pulse shape is influenced by the distance that the hot electrons diffuse before losing their energy to the lattice. We show that this method can be used to test theories of the electron-phonon and electron-electron scattering rates.
, Tas, , Maris
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Picosecond ultrasonics in gold nanoparticles

The Journal of the Acoustical Society of America, 1999
Pump–probe optical techniques with femtosecond laser sources can be used to provide information about the acoustical properties of very thin films. With this so-called ‘‘picosecond ultrasonics technique,’’ echoes shorter than 10 ps can be time-resolved in films whose thicknesses are larger than a few tens of nm; for smaller thicknesses, the acoustic ...
Arnaud Devos, Bernard Perrin, Jean Claude Jeannet   +2 more
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Probing single-cell mechanics with picosecond ultrasonics

Ultrasonics, 2015
The mechanical properties of cells play a key role in several fundamental biological processes, such as migration, proliferation, differentiation and tissue morphogenesis. The complexity of the inner cell composition and the intricate meshwork formed by transmembrane cell-substrate interactions demands a non-invasive technique to probe cell mechanics ...
Dehoux, Thomas, Abi Ghanem, Maroun, Zouani, Omar, Ducousso, Mathieu, Chigarev, Nikolay, Rossignol, Clément, Tsapis, Nicolas, Durrieu, Marie-Christine, Audoin, Bertrand   +8 more
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Picosecond Ultrasonics: The prefered tool for BAW characterization

2008 IEEE Ultrasonics Symposium, 2008
Since the 80's, RF-filtering has carried the developments of Bulk Acoustic Wave (BAW) resonators. At the same time, picosecond ultrasonics, a non-contact and non-destructive technique for mechanical characterization, sees the light of day as an on-product process control measurements technique.
Emery, P., Devos, Arnaud, Ancey, P.
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Picosecond ultrasonics in a single biological cell

2008 IEEE Ultrasonics Symposium, 2008
Picosecond ultrasonics is a non-destructive method for measuring mechanical and thermal properties such as sound velocity or heat conductivity at sub-micron scale. This technique uses femtosecond laser pulses for generating and detecting GHz acoustics waves.
M. Ducousso, C. Rossignol, B. Audoin, F. Guillemot, M.C. Durrieu   +4 more
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Picosecond ultrasonic measurements using an optical mask

Ultrasonics, 2015
In this paper we describe results obtained using a variation of the picosecond ultrasonics technique. We place a transparent optical mask very close to the surface of the sample. The lower surface of the mask has a series of grooves to produce a variation of the intensity of the pump and probe light pulses across the surface of the sample.
Q, Miao, L-W, Liu, T J, Grimsley, A V, Nurmikko, H J, Maris   +4 more
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Mechanical contacts probed with picosecond ultrasonics

The Journal of the Acoustical Society of America, 2008
We investigate the contact between a thin metal film and a ball bearing indented to nanometre depths using picosecond ultrasonics. The area of contact is acoustically imaged to micron spatial resolution using GHz acoustic pulses produced by ultrashort pulsed optical excitation of the film through a transparent substrate.
Thomas Dehoux, Motonobu Tomoda, Oliver B. Wright   +2 more
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The development of picosecond ultrasonics

The Journal of the Acoustical Society of America, 2006
Brown University has been a center for acoustics research for a very long time. Over the past 20 years, efforts have been directed towards the development of a new measurement technique that makes possible experiments on very thin films and other small structures of current interest in the computer industry.
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Piezoelectric coefficients measured by picosecond ultrasonics

2009 IEEE International Ultrasonics Symposium, 2009
The needs for materials in thin films characterization are increasing with the raising interest for Micro-Electro-Mechanical-Systems. Picosecond ultrasonics (PU), a non-contact and non-destructive technique, has been largely developed to answer the mechanical metrology requirements of thin films technology, particularly in the field of Bulk Acoustic ...
Emery, P., Devos, Arnaud, Ben Hassine, N., Defay, E.   +3 more
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Picosecond ultrasonics study of metallic multilayers

Physica B: Condensed Matter, 1996
Abstract A picosecond ultrasonics study of Cu/W superlattices in periods between 5 and 20 nm has been performed. Determination of acoustic echoes, observed over 200 ps, showed a softening of the longitudinal elastic constant for the shortest periods. High frequency oscillations were also detected over the first 20 ps.
B. Perrin, B. Bonello, J.-C. Jeannet, E. Romatet   +3 more
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