We improve the existing data extraction algorithms for THz time-domain spectroscopy (THz TDS) in two aspects. On the one hand, we merge the up-to-date knowledge of THz TDS signal processing into a single powerful optical material parameter extraction algorithm. On the other hand, we introduce a novel iterative algorithm that further enhances the accuracy of the parameter extraction. In contrast to most of the published experiments, we are able to reliably investigate samples with thicknesses as small as 100microm, samples with low indexes of refraction, i.e. close to 1, as well as samples with sharp peaks in the material parameter curves.

Field and laboratory experiments were carried out in 2012–2013, aimed at evaluating the influence of new products stimulating plant growth based on amino acids on crop yield, characteristics of grain and content of macro- and micronutrients in winter wheat (Triticum aestivum L.). The tests included two formulations produced in cooperation with INTERMAG Co. (Olkusz, Poland)—AminoPrim and AminoHort, containing 15% and 20% amino acids, respectively, and 0.27% and 2.1% microelements, respectively. Field experiments showed that the application of products based on amino acids influenced the increase of grain yield of winter wheat (5.4% and 11%, respectively, for the application of AminoPrim at a dose 1.0 L/ha and AminoHort at dose 1.25 L/ha) when compared to the control group without biostimulant. Laboratory tests showed an increase of technological characteristics of grain such as ash content, Zeleny sedimentation index and content of protein. The use of the tested preparations at different doses also contributed to the increase of the nutrients content in grains, in particular copper (ranging 31–50%), as well as sodium (35–43%), calcium (4.3–7.9%) and molybdenum (3.9–16%). Biostimulants based on amino acids, tested in the present study, can be recommended for an efficient agricultural production.

Abstract:We use terahertz time-domain spectroscopy (THz-TDS) to measure the far-infrared dielectric function of two artificial RNA single strands, composed of polyadenylic acid (poly-A) and polycytidylic acid (poly-C). We find a significant difference in the absorption between the two types of RNA strands, and we show that we can use this difference to record images of spot arrays of the RNA strands. Under controlled conditions it is possible to use the THz image to distinguish between the two RNA strands. We discuss the requirements to sample preparation imposed by the lack of sharp spectral features in the absorption spectra.

Most time-resolved optical experiments rely either on external mechanical delay lines or on two synchronized femtosecond lasers to achieve a defined temporal delay between two optical pulses. Here, we present a new method which does not require any external delay lines and uses only a single femtosecond laser. It is based on the cross-correlation of an optical pulse with a subsequent pulse from the same laser. Temporal delay between these two pulses is achieved by varying the repetition rate of the laser. We validate the new scheme by a comparison with a cross-correlation measurement carried out with a conventional mechanical delay line.