Electromagnetic Wave Spectroscopy Research Articles

Real-Time Microwave, Dielectric, and Optical Sensing of Lincomycin and Tylosin Antibiotics in Water: Sensor Fusion for Environmental Safety

Antibiotics are widely used to prevent and treat bacterial infections in livestock animals, aquaculture, and humans. However, the unconditional use of those drugs as a growth promoter for livestock animals and the wrong usage as a treatment for infections in humans has led to high antibiotics pollution, especially in water resources. The elevated presence of antibiotics in water has resulted in the phenomenon known as the bacterial antibiotics resistance. To prevent ecological catastrophe, continuous real-time monitoring of water sources is necessary. The aim of this research work is to compare the abilities of three different techniques: novel electromagnetic wave spectroscopy, UV-Vis spectrophotometry, and capacitance sensing system for the real-time detection and quantification of antibiotics in water. Tylosin and lincomycin antibiotics were selected to the study, as both are regularly found in water sources. Two novel microwave sensor configurations were used: a planar sensor with interdigitated electrode pattern and a hairpin resonator sensor, as a means of real-time water analysis. Reflected S11 power signals were analyzed in GHz frequency range for microwave sensors. In parallel, UV-Vis spectrophotometry was used, where change in the optical absorbance was used as an indicator of water pollution, whereas change in the value of a capacitance in low frequency range has signalled the change in the dielectric properties of the solution. It was found that in all cases the changes in the measured parameters were dependent on both the type of antibiotic present in water and on its concentration. Fusion of all these techniques into a comprehensive sensing platform provides adequate real-time assessment of the water pollution with antibiotics and would allow adequate management of environment for safety and sustainable development. In particular, the lowest lincomycin samples’ concentration, 0.25 μg/l, was measured with a hairpin resonator sensor, while the lowest tylosin samples’ concentration, 0.20 μg/l, was measured with an IDE sensor. Since concentration in groundwater were 0.36 μg/l of lincomycin and 1.5 μg/l of tylosin, it is demonstrating a high-sensing platform utility.

Nondestructive evaluation on dispersion of steel fibers in UHPC using THz electromagnetic waves

Ultra-high performance concrete (UHPC), which has better mechanical properties and durability than reinforced concrete, can greatly reduce the weight of structures due to its high strength and reliability. So, it is very effective for the construction of high-rise buildings and long-span bridges. The mix design for UHPC is not only composed of traditional materials (i.e. cement, sand, and aggregate) but also includes binder and admixture. Moreover, steel fiber is necessary to improve ductility. Since the tensile strength of UHPC depends greatly on the direction of the steel fiber, it is important to confirm the dispersibility and orientation of the steel fiber. However, verification of the dispersibility of the steel fiber after curing is indirectly performed through destructive methods like strength tests through coring. Thus, for a better method of dispersibility confirmation, a more effective dispersion analysis technique is required. In this study, the dispersibility of steel fiber in UHPC was evaluated through tomography of UHPC using THz electromagnetic waves. These waves have both infrared straightness and microwave penetrability. Three UHPC specimens were fabricated with steel fiber and were tested with THz electromagnetic wave spectroscopy by experimentally scanning the specimen. From the experimental results, it was possible to obtain a 3D image of the steel fiber arrangement inside the specimen through scanning of the specimen. Also, through image analysis, the dispersibility of the steel fiber in each specimen was numerically derived. For the future, it is expected that the dispersion analysis technology proposed in this study will be applied as an automated nondestructive testing method for enhanced quality control.

Emission of the terahertz electromagnetic wave from coherent longitudinal optical phonons in a GaAs buffer layer optically masked by a GaSb top epitaxial layer

We demonstrate that, in a GaSb/GaAs epitaxial structure, the coherent longitudinal optical (LO) phonon in the GaAs layer optically masked by the GaSb top layer is observed utilizing terahertz- electromagnetic-wave spectroscopy. It is confirmed from a Raman scattering measurement that only the optical phonon in the GaSb layer is optically observable, where the photon energy of the excitation laser beam was almost the same as that of the femtosecond pulse pump beam for the terahertz wave measurement. In the terahertz wave measurement, the Fourier power spectrum of the terahertz waveform exhibits both the GaAs and the GaSb LO phonons; namely, the coherent LO phonon in the optically masked GaAs buffer layer is observed in the terahertz wave measurement. This fact demonstrates that the instantaneous surface potential modulation originating from the impulsive carrier excitation by the pump pulses reaches the GaAs buffer layer. Consequently, the above-mentioned surface potential modulation generates the coherent GaAs LO phonon.

Breathers in Josephson junction ladders: resonances and electromagnetic wave spectroscopy.

We present a theoretical study of the resonant interaction between dynamical localized states (discrete breathers) and linear electromagnetic excitations (EE's) in Josephson junction ladders. By making use of direct numerical simulations we find that such an interaction manifests itself by resonant steps and various sharp switchings (voltage jumps) in the current-voltage characteristics. Moreover, the power of ac oscillations away from the breather center (the breather tail) displays singularities as the externally applied dc bias decreases. All these features may be mapped to the spectrum of EE's that has been derived analytically and numerically. Using an improved analysis of the breather tail, a spectroscopy of the EE's is developed. The nature of breather instability driven by localized EE's is established.

Qualitative Analysis of Nanogram Samples with Fourier Transform Infrared Transmission Surface Electromagnetic Wave Spectroscopy

The intensity enhancement of infrared spectra with Ag island films in surface electromagnetic wave spectroscopy (SEWS), which is commonly associated with the ATR method, was observed with the use of an ordinary transmission configuration. We refer to this as “transmission SEWS” or “T-SEWS.” With 10 nm Ag, the magnitude of enhancement factor was about 200 for the NO2 symmetric stretching band at 1350 cm−1 with p-nitrobenzoic acid. In order to estimate its effectiveness as a qualitative analytical method, T-SEWS spectra were compared with normal transmission spectra with the use of several samples. The results showed that T-SEWS is useful in detecting and identifying nanogram amounts of substances which do not have reactive functional groups—e.g., triphenyl phosphate (TPP) or polydimethylsiloxane (PDMS), which do not have -COOH, -SO3H, -C=S, etc. A usable spectrum was observed from as little as 25 ng/cm2 of TPP with the use of a standard triglycine sulfate detector without a beam condenser. Combined with microspectroscopy, T-SEWS shows promise for picogram order analysis and chromatographic applications.

Fourier transform ir reflection techniques for characterization of polyimide films on copper substrates

The interaction of polyimide and copper at elevated temperatures is poorly understood, despite the fact that this system is of great importance for various microelectronic devices. In this study, we have used Fourier transform IR spectroscopy to study the copper-catalyzed degradation of polyimide and its precursor, polyamic acid. We have examined this system in both air and nitrogen and with both copper and chromium as test substrates. Also discussed in this paper is the application of two new spectroscopy techniques: surface electromagnetic wave spectroscopy and grazing-angle-incident metal overlayer attenuated total reflection spectroscopy. The increased sensitivity offered by these techniques is far and above that of traditional reflection-absorption spectroscopy. We are also able to study the different interfaces that exist between the copper and the polyimide with the metal overlayer technique. The combined use of all three experimental methods allows us to examine the interfacial regions of the polyimide/copper system fully.

Infrared study of hydrogen chemisorbed on W (100) by surface electromagnetic wave spectroscopy

The inhibition of the structure c(2x2)H or c(2x2)D reconstruction in the case of H or D chemisorption on the surface W(100) is observed by surface electromagnetic wave spectroscopy. The strong band at 960 cm−1 is referred to overtone of wagging mode.

FT-IR surface electromagnetic waves (SEW) absorption spectroscopy of very thin films on metals

Two methods are compared experimentally and theoretically: surface electromagnetic wave spectroscopy (SEWS) and infrared reflection-absorption spectroscopy (IRAS) at the angle of incidence 88°. On the example of the 4-n-octadecylphenol Langmuir films on copper it was shown that the sensitivity of SEWS is about one order greater than that of IRAS, the ratio of sensitivities growing with the increase of the film thickness. A Fourier-spectrometer for broad band IR spectra measurements was used.

High-Resolution Infrared Study of Hydrogen (1×1) on Tungsten (100)

The first high-resolution observation of the ${\ensuremath{\nu}}_{1}$ vibrational mode of H chemisorbed on W(100) at saturation coverage has been obtained by surface electromagnetic wave spectroscopy.

3867. ir study of molecules adsorbed on metal surfaces by surface electromagnetic wave spectroscopy. (USA)

3867. ir study of molecules adsorbed on metal surfaces by surface electromagnetic wave spectroscopy. (USA)

Ir study of molecules adsorbed on metal surfaces by surface electromagnetic wave spectroscopy

The infrared spectra of monolayer coverages of two different molecules (KReO4 and SF6) physisorbed on metal surfaces have been measured in the 10-μm region by means of a new surface electromagnetic wave (SEW) coupling technique in conjunction with a CO2 laser. Coverages as low as two monolayers can be readily monitored in agreement with predictions based on an optical sum rule. The new coupling configuration is based on the principle of inhomogeneous wave coupling and allows the matching of both the propagation wave vector and the spatial profile of the SEW. Our method is both more efficient and more convenient for SEW spectroscopy than the conventional prism technique.