Microwave Diamond-Based HBAR as a Highly Sensitive Sensor for Multiple Applications: Acoustic Attenuation in the Mo Film

The application of microwave diamond-based HBAR as a sensor of microwave acoustic attenuation α was considered, using the Mo film as an object of research. A multilayered piezoelectric structure, as the Al/Al_0.73Sc_0.27N/Mo/(100) diamond/Mo, was produced using aluminum-scandium nitride composition, and was studied in detail for a number of the Mo films with different thicknesses obtained by magnetron deposition. The operational frequency band of 3.3 … 18 GHz was used. It was found that the dependence of the resonant frequency shift vs. the h(Mo) thickness for all the overtones to be investigated was linear. For a given sensor, it was found that the mass sensitivity per unit area r_m was equal to -26 × 10^-12 and -8.7 × 10^-12 g/(cm²∙Hz) at 6.0 GHz and 18.3 GHz, respectively. The frequency dependencies of quality factor Q, which changed as a result of Mo film deposition, were considered as the basic experimental data. A method for extracting the α(Mo) values was proposed. The Q-factor under the complete deposition of Mo film was 936 nm, and dropped moderately to ~25%. Such values were enough for an aim of the given experiment. The α(f) in molybdenum was obtained, and demonstrated a dependence that was close to quadratic, corresponding to the Akhiezer attenuation law.

Femtosecond X-ray spectroscopy of haem proteins

We discuss our recently reported femtosecond (fs) X-ray emission spectroscopy results on the ligand dissociation and recombination in nitrosylmyoglobin (MbNO) in the context of previous studies on ferrous haem proteins. We also present a preliminary account of femtosecond X-ray absorption studies on MbNO, pointing to the presence of more than one species formed upon photolysis.

Calculation of the dispersive characteristics of acoustic waves in piezoelectric layered structures under the effect of DC electric field

Relations used for calculation of the layered piezoelectric structures parameters, including the influence of the uniform dc electric field, have been obtained. Dispersive dependences and anisotropy of phase velocities, electromechanical coupling coefficients, power flow angle, and the influence of controlling coefficients of the dc electric field as a function of the h × f product for the Rayleigh and Love modes in bismuth germanium oxide/fused silica and langasite/fused silica layered structures have been calculated.