Oblique growth of iron thin films on glass: a cross-sectional transmission electron microscopy study

Fréchard, P.; Andrieu, S.; Chateigner, D.; Hallouis, M.; Germi, P.; Pernet, M.

doi:10.1016/0040-6090(95)06552-0

Cited by 8 publications

(3 citation statements)

References 13 publications

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“…The excitation pulses from a Ti:Sapphire amplifier system (Coherent RegA) operating at a 250 kHz repetition rate were centered around 790 nm with a bandwidth of about 8 nm and a pulse duration of 200 fs, and were focused on the sample to a 100 μm spot. Semitransparent transducer thin films were obliquely deposited under ultrahigh vacuum by molecular beam epitaxy 45 onto optical quality sapphire or BK7 glass substrates. The substrates consisted of monocrystalline columnar layers of iron with thicknesses between 40-50 nm and an average inclination angle of the iron grains of about 40 • .…”

Section: Experimental Techniquesmentioning

confidence: 99%

Mechanical spectra of glass-forming liquids. II. Gigahertz-frequency longitudinal and shear acoustic dynamics in glycerol and DC704 studied by time-domain Brillouin scattering

Klieber

Hecksher

Pézeril

et al. 2013

The Journal of Chemical Physics

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This paper presents and discusses the temperature and frequency dependence of the longitudinal and shear viscoelastic response at MHz and GHz frequencies of the intermediate glass former glycerol and the fragile glass former tetramethyl-tetraphenyl-trisiloxane (DC704). Measurements were performed using the recently developed time-domain Brillouin scattering technique, in which acoustic waves are generated optically, propagated through nm thin liquid layers of different thicknesses, and detected optically after transmission into a transparent detection substrate. This allows for a determination of the frequency dependence of the speed of sound and the sound-wave attenuation. When the data are converted into mechanical moduli, a linear relationship between longitudinal and shear acoustic moduli is revealed, which is consistent with the generalized Cauchy relation. In glycerol, the temperature dependence of the shear acoustic relaxation time agrees well with literature data for dielectric measurements. In DC704, combining the new data with data from measurements obtained previously by piezo-ceramic transducers yields figures showing the longitudinal and shear sound velocities at frequencies from mHz to GHz over an extended range of temperatures. The shoving model's prediction for the relaxation time's temperature dependence is fairly well obeyed for both liquids as demonstrated from a plot with no adjustable parameters. Finally, we show that for both liquids the instantaneous shear modulus follows an exponential temperature dependence to a good approximation, as predicted by Granato's interstitialcy model.

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Section: Experimental Techniquesmentioning

confidence: 99%

Mechanical spectra of glass-forming liquids. II. Gigahertz-frequency longitudinal and shear acoustic dynamics in glycerol and DC704 studied by time-domain Brillouin scattering

Klieber

Hecksher

Pézeril

et al. 2013

The Journal of Chemical Physics

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“…1), longitudinal and shear acoustic waves were optically generated in an iron semitransparent thin film upon ultrafast laser irradiation. The iron films of about 50 nm thickness were obliquely deposited under ultrahigh vacuum [15], with an oblique incidence angle of 60 , providing a tilt of the crystal symmetry axis of about 40…”

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confidence: 99%

Optical Generation of Gigahertz-Frequency Shear Acoustic Waves in Liquid Glycerol

et al. 2009

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Picosecond laser ultrasonic techniques for acoustic wave generation and detection have been employed to probe shear acoustic waves in liquid glycerol at gigahertz frequencies. The experimental approach uses a unique laser pulse shaping technique and a crystallographically canted metal layer to generate frequency-tunable transverse acoustic waves, and uses time-domain coherent Brillouin scattering to detect the waves after they propagate through a liquid layer and into a solid substrate. A linear frequency dependence is found for both the shear speed and attenuation rate in glycerol. DOI: 10.1103/PhysRevLett.102.107402 PACS numbers: 78.20.Hp, 43.35.+d, 78.40.Dw, 78.47.JÀ Fast structural relaxation dynamics in liquids continue to pose major fundamental challenges [1], in large measure because direct experimental access to key relaxing degrees of freedom over the time or frequency ranges of interest remains elusive. Both density and shear relaxation play central roles in the complex structural responses of viscoelastic materials. On slow time scales, dynamic mechanical analysis and sonic or related measurement methods can be used, while faster responses require measurements of longitudinal and shear acoustic waves in the megahertz and gigahertz frequency ranges. Much of the MHz range is now accessible to ultrasonics and impulsive stimulated thermal or Brillouin scattering (impulsive stimulated thermal or Brillouin scattering [2-5]), and (usually isolated) frequencies in the low GHz range may be accessed through spontaneous Brillouin scattering [6]. Recent work in x-ray Brillouin scattering has accessed THz longitudinal acoustic frequency ranges [7], but frequencies in the tens to hundreds of GHz range, where fast relaxation features occur, have remained difficult to access. Deep-UV Brillouin scattering from longitudinal acoustic waves in this range has been demonstrated [4,7], but its utility is limited by strong absorption in most materials. Picosecond ultrasonics [8], in which a short optical pulse generates a single-cycle acoustic pulse that is observed after propagation through a sample, has provided tabletop access to much of the GHz-frequency range for longitudinal acoustic waves. Adaptations of the method to enable GHz shear wave generation [9][10][11][12] have been developed. However, shear waves in liquids have remained elusive, to the extent that the challenges in ''seeking shear waves in liquids with picoseconds ultrasonics'' [13] have been elaborated explicitly. The use of multiple optical pulses to generate frequency-tunable, multiple-cycle longitudinal waves [14] has been demonstrated to improve acoustic spectral brightness for characterization of frequency-dependent material responses. Here we demonstrate this approach for generation of frequency-tunable shear as well as longitudinal acoustic waves in the GHz-frequency range. We further demonstrate a sample and optical configuration that permit the measurements to be conducted in viscoelastic liquids, whose GHz-frequency acoustic responses are of...

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“…The iron films of about 50 nm thickness were obliquely deposited under ultra-high vacuum, 20 with an oblique incidence angle of 60…”

Section: Picosecond Shear Waves In Liquidsmentioning

confidence: 99%

Picosecond shear waves in nano-sized solids and liquids

et al. 2009

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We will review recent progress on the generation and detection of picosecond shear acoustic waves. Examples will be shown in which the transverse isotropic symmetry of the sample structure is broken in order to permit shear wave generation through sudden laser heating. As an illustration of the technique, picosecond longitudinal and shear acoustic waves have been successfully employed to probe structural dynamics in nano-sized solids (gold nano-crystals assemblies) and nano-sized liquids (glycerol and water).

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Oblique growth of iron thin films on glass: a cross-sectional transmission electron microscopy study

Cited by 8 publications

References 13 publications

Mechanical spectra of glass-forming liquids. II. Gigahertz-frequency longitudinal and shear acoustic dynamics in glycerol and DC704 studied by time-domain Brillouin scattering

Mechanical spectra of glass-forming liquids. II. Gigahertz-frequency longitudinal and shear acoustic dynamics in glycerol and DC704 studied by time-domain Brillouin scattering

Optical Generation of Gigahertz-Frequency Shear Acoustic Waves in Liquid Glycerol

Picosecond shear waves in nano-sized solids and liquids

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