Vitreous SiO2 thin films thermally grown onto Si wafers were bombarded by Au ions with energies from 0.005 to 11.1 MeV/u and by ions at constant velocity (0.1 MeV/u A197u, T130e, A75s, S32, and F19). Subsequent chemical etching produced conical holes in the films with apertures from a few tens to ∼150 nm. The diameter and the cone angle of the holes were determined as a function of energy loss of the ions. Preferential track etching requires a critical electronic stopping power Seth∼2 keV/nm, independent of the value of the nuclear stopping. However, homogeneous etching, characterized by small cone opening angles and narrow distributions of pore sizes and associated with a continuous trail of critical damage, is only reached for Se>4 keV/nm. The evolution of the etched-track dimensions as a function of specific energy (or electronic stopping force) can be described by the inelastic thermal spike model, assuming that the etchable track results from the quenching of a zone which contains sufficient energy for melting. The model correctly predicts the threshold for the appearance of track etching Seth if the radius of the molten region has at least 1.6 nm. Homogeneous etching comes out only for latent track radii larger than 3 nm.

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Magnetization dynamic response of coupled and uncoupled spin valves with structure NiFe(20nm)/Cu(tCu)/NiFe(20nm)/IrMn(10nm) is probed using broadband ferromagnetic resonance absorption measurements. The coupling intensity between the free and pinned layers is tailored by varying the Cu thickness tCu. Broadband spectra exhibit two resonant modes for each value of applied field. It is observed that the coupling among NiFe layers modifies the amplitude of the absorption peaks and also the shape of the dispersion relations for each mode, which becomes particularly distorted at the anti-parallel magnetization state. The observed phenomena is well described by applying a semianalytical model that properly takes into account the coupling interactions and allows an efficient numerical calculation of the absorption peak amplitudes, and the dispersion relation shapes.

This work presents an approach for the estimation of the adsorbed mass of 1,5-diaminopentane (cadaverine) on a functionalized piezoelectrically driven microcantilever (PD-MC) sensor, using a polynomial developed from the characterization of the resonance frequency response to the known added mass. This work supplements the previous studies we carried out on the development of an electronic nose for the measurement of cadaverine in meat and fish, as a determinant of its freshness. An analytical transverse vibration analysis of a chosen microcantilever beam with given dimensions and desired resonance frequency (> 10 kHz) was conducted. Since the beam is considered stepped with both geometrical and material non-uniformity, a modal solution for stepped beams, extendable to clamped-free beams of any shape and structure, is derived and used for free and forced vibration analyses of the beam. The forced vibration analysis is then used for transformation to an equivalent electrical model, to address the fact that the microcantilever is both electronically actuated and read. An analytical resonance frequency response to the mass added is obtained by adding simulated masses to the free end of the beam. Experimental verification of the resonance frequency response is carried out, by applying known masses to the microcantilever while measuring the resonance frequency response using an impedance analyzer. The obtained response is then transformed into a resonance frequency to the added mass response polynomial using a polynomial fit. The resulting polynomial is then verified for performance using different masses of cantilever functionalization solution. The functionalized cantilever is then exposed to different concentrations of cadaverine while measuring the resonance frequency and mass of cadaverine adsorbed estimated using the previously obtained polynomial. The result is that there is the possibility of using this approach to estimate the mass of cadaverine gas adsorbed on a functionalized microcantilever, but the effectiveness of this approach is highly dependent on the known masses used for the development of the response polynomial model.