Advances in quantitative nanoscale subsurface imaging by mode-synthesizing atomic force microscopy

This paper reports on advances toward quantitative non-destructive nanoscale subsurface investigation of a nanofabricated sample based on mode synthesizing atomic force microscopy with heterodyne detection, addressing the need to correlate the role of actuation frequencies of the probe f(p) and the sample f(s) with depth resolution for 3D tomography reconstruction. Here, by developing a simple model and validating the approach experimentally through the study of the nanofabricated calibration depth samples consisting of buried metallic patterns, we demonstrate avenues for quantitative nanoscale subsurface imaging. Our findings enable the reconstruction of the sample depth profile and allow high fidelity resolution of the buried nanostructures. Non-destructive quantitative nanoscale subsurface imaging offers great promise in the study of the structures and properties of complex systems at the nanoscale

Validation of ozone measurements from the Atmospheric Chemistry Experiment (ACE)

This paper presents extensive bias determination analyses of ozone observations from the Atmospheric Chemistry Experiment (ACE) satellite instruments: the ACE Fourier Transform Spectrometer (ACE-FTS) and the Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation (ACE-MAESTRO) instrument. Here we compare the latest ozone data products from ACE-FTS and ACE-MAESTRO with coincident observations from nearly 20 satellite-borne, airborne, balloon-borne and ground-based instruments, by analysing volume mixing ratio profiles and partial column densities. The ACE-FTS version 2.2 Ozone Update product reports more ozone than most correlative measurements from the upper troposphere to the lower mesosphere. At altitude levels from 16 to 44 km, the average values of the mean relative differences are nearly all within +1 to +8%. At higher altitudes (45 60 km), the ACE-FTS ozone amounts are significantly larger than those of the comparison instruments, with mean relative differences of up to +40% (about + 20% on average). For the ACE-MAESTRO version 1.2 ozone data product, mean relative differences are within +/- 10% (average values within +/- 6%) between 18 and 40 km for both the sunrise and sunset measurements. At higher altitudes (similar to 35-55 km), systematic biases of opposite sign are found between the ACE-MAESTRO sunrise and sunset observations. While ozone amounts derived from the ACE-MAESTRO sunrise occultation data are often smaller than the coincident observations (with mean relative differences down to -10%), the sunset occultation profiles for ACE-MAESTRO show results that are qualitatively similar to ACE-FTS, indicating a large positive bias (mean relative differences within +10 to +30%) in the 45-55 km altitude range. In contrast, there is no significant systematic difference in bias found for the ACE-FTS sunrise and sunset measurements

Elasticity and lattice vibrational properties of transparent polycrystalline yttrium–aluminium garnet: Experiments and pair potential calculations

Brillouin light scattering, Raman light scattering and visible–infrared reflectometry techniques have been used to investigate, respectively, the elastic properties, the phonons and the optical properties of bulk textured polycrystalline yttrium–aluminum garnet doped with 2 at% neodymium obtained by the sintering of commercial oxides. From the analysis of the observed bulk longitudinal and transverse acoustic modes with the knowledge of the refractive index 1.81 inferred from the visible reflectometry, the two independent effective elastic constants of the isotropic polycrystal C11 = 362 GPa and (C11 −C12)/2 = 121 GPa are determined leading to the value of the bulk modulus B = (C11 +2C12)/3 = 200 GPa. The ratio ε0/ε∞ = 3.1 and the optic permittivity ε∞ = 3.46 are derived from the infrared reflectivity data. Pair potential calculations of the three single crystal elastic constants c11 = 340, c12 = 127 and c44 = 112 GPa, of the bulk modulus B = (c11 +2c12)/3 = 198 GPa, of the zone-center () phonons and of the permittivity function provide good comparison with our experimental results

Nanoscale Subsurface Imaging

The ability to probe structures and functional properties of complex systems at the nanoscale, both at their surface and in their volume, has drawn substantial attention in recent years. Besides detecting heterogeneities, cracks and defects below the surface, more advanced explorations of chemical or electrical properties are of great interest. In this article, we review some approaches developed to explore heterogeneities below the surface, including recent progress in the different aspects of metrology in optics, electron microscopy, and scanning probe microscopy. We discuss the principle and mechanisms of image formation associated with each technique, including data acquisition, data analysis and modeling for nanoscale structural and functional imaging. We highlight the advances based on atomic force microscopy (AFM). Our discussion first introduces methods providing structural information of the buried structures, such as position in the volume and geometry. Next we present how functional properties including conductivity, capacitance, and composition can be extracted from the modalities available to date and how they could eventually enable tomography reconstructions of systems such as overlay structures in transistors or living systems. Finally we propose a perspective regarding the outstanding challenges and needs to push the field forward

Réalisation de films piézoélectriques de nitrure d'aluminium par dépôt chimique en phase vapeur assisté par plasma

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Freeze-dried nanometric neodymium-doped YAG powders for transparent ceramics

Nanometric neodymium-doped yttrium aluminium garnet (YAG) has been synthesised from freeze-dried precursors. The productswere calcined between 900 ◦C and 1200 ◦C under flowing oxygen. Powder morphologies were observed by TEM, SEM and laser granulometer. The oxides had small crystallite size. The best sinterability under vacuum at 1700 ◦C for 3h was obtained for precursors with the lowest amount of organic impurities as indicated by IR measurements. Hot isostatic pressing at 1700 ◦C in 160MPa of argon was applied to complete the sintering. Under these conditions, Nd:YAG ceramics with very good transmittance were obtained

SYRACO (SYstème de Reconnaissance Automatique de COccolithes) is a software that pilots an automatic microscope and a digital camera in order to automatically recognize coccolith species and measure their morphological characteristic based on artificial neural networks. The first version was displayed in 1996 (Dollfus and Beaufort, 1996; 1999) and was scientifically used for the first time in 2001 (Beaufort et al., 2001). SYRACO evolved during the last 20 years in many aspects such as the architecture of the neural networks, the image scanning and pre-treatments. Twenty years ago, SYRACO was dedicated to quaternary paleoceanographic studies, because it was able to recognize morphological classes. With all the developments, it is now able to be used in biostratigraphy as it is able to determine coccolith species. The latest version of SYRACO will be described, and an example of application to a south Pacific core will be given. Beaufort, L., de Garidel Thoron , T., Mix, A. C., and Pisias, N. G.: ENSO-like forcing on Oceanic Primary Production during the late Pleistocene, Science, 293, 2440-2444, 2001.Dollfus, D., and Beaufort, L.: Automatic pattern recognition of calcareous nannoplankton, Neural Network and their Applications : NEURAP 96, Marseille, France, 1996, 306-311, Dollfus, D., and Beaufort, L.: Fat neural network for recognition of position-normalised objects, Neural Networks, 12, 553-560, 1999.

International audienc

SYRACO (SYstème de Reconnaissance Automatique de COccolithes) is a software that pilots an automatic microscope and a digital camera in order to automatically recognize coccolith species and measure their morphological characteristic based on artificial neural networks. The first version was displayed in 1996 (Dollfus and Beaufort, 1996; 1999) and was scientifically used for the first time in 2001 (Beaufort et al., 2001). SYRACO evolved during the last 20 years in many aspects such as the architecture of the neural networks, the image scanning and pre-treatments. Twenty years ago, SYRACO was dedicated to quaternary paleoceanographic studies, because it was able to recognize morphological classes. With all the developments, it is now able to be used in biostratigraphy as it is able to determine coccolith species. The latest version of SYRACO will be described, and an example of application to a south Pacific core will be given. Beaufort, L., de Garidel Thoron , T., Mix, A. C., and Pisias, N. G.: ENSO-like forcing on Oceanic Primary Production during the late Pleistocene, Science, 293, 2440-2444, 2001.Dollfus, D., and Beaufort, L.: Automatic pattern recognition of calcareous nannoplankton, Neural Network and their Applications : NEURAP 96, Marseille, France, 1996, 306-311, Dollfus, D., and Beaufort, L.: Fat neural network for recognition of position-normalised objects, Neural Networks, 12, 553-560, 1999.

International audienc