Electrical detection of Rydberg interactions in nitric oxide at room temperature

In this work I will present measurements of Rydberg states in nitric oxide (NO) at room temperature. The detection of the Rydberg states is realized by measuring the current of free charges resulting from collisions of the excited molecules. All measurements are performed using continuous-wave (cw) lasers in a sub-Doppler configuration, which together with a stabilization setup yield a frequency error of only 2 × 2.5 MHz. The full width at half maximum (FWHM) of a typical Rydberg state is only about 2 × 130 MHz. We take a look at the necessary theory of diatomic molecules first. Afterward, a thorough walkthrough of the experimental setup is given. The heart of our setup is a custom-designed measurement cell, which features readout electronics based on a transimpedance amplifier (TIA). As such I will also give an overview on the basics of operational amplifiers (OpAmps). When all prerequisites are introduced, we will take an in-depth look on the Stark effect in Rydberg states. To our knowledge, the presented resolution is unmatched, and may enable us to give a more precise value to the g–quantum defect in NO in the future. In a final experimental section I show the collisional broadening and shift of Rydberg states of NO due to an increasing background gas density. Such measurements have a long history in alkalis, yet to our knowledge, no such measurements in NO exist. The overall experiment is performed in the context of a trace-gas sensor for NO in a medical application. This work gives suitable density and electric field ranges for such a sensor

Seagrass systems: stability of seagrass systems against anthropogenic impacts

The study presented here examines which factors directly or indirectly connected to eutrophication, are relevant to the deterioration of seagrass populations in the Baltic Sea/Greifswalder Bodden. More particularly it is a study of the interaction effects of seagrass autotrophic competitors (epiphytic algae, drifting macroalgae and phytoplankton) on seagrass. These are interesting yet largely studied and were, in this study, investigated through the field observations and experiments of a seagrass population in the Greifswalder Bodden, Germany. Additionally to get a better understanding of the current state of the seagrass meadows and the light conditions in the Bodden, the historical development of the macrophyte populations under the influence of the eutrophication and the changing light climate were analysed over the last 25 year and discussed according to the model of "ecosystem shifts"

Cyanobacteria Blooms in the Baltic Sea: A Review of Models and Facts

The ecosystem of the Baltic Sea is endangered by eutrophication. This has triggered expensive international management efforts. Some of these efforts are impeded by natural processes such as nitrogen-fixing cyanobacteria blooms that add bioavailable nitrogen to the already over-fertilized system and thereby enhance primary production, export of organic matter to depth, and associated oxygen consumption. Controls of cyanobacteria blooms are not comprehensively understood, and this adds to the uncertainty of model-based projections into the warming future of the Baltic Sea. Here we review our current understanding of cyanobacteria bloom dynamics. We summarize published field studies and laboratory experiments and dissect the basic principles ingrained in state-of-the-art coupled ocean–circulation biogeochemical models

Epibenthic communities associated with unintentional artificial reefs (modern shipwrecks) under contrasting regimes of nutrients in the Levantine Sea (Cyprus and Lebanon)

Artificial reefs, in the Eastern Mediterranean (Cyprus,) became a popular and frequently used tool, in fisheries and biodiversity conservation management. Even though evaluation studies about the efficacy of artificial reefs are plentiful in the rest of the Mediterranean (Central and Western), in the Eastern Basin they are largely absent. As the Eastern part of the Mediterranean Sea is characterised by unique physical parameters, the necessity to study artificial reefs under these contrasting regimes increases. The epibenthic communities of two unintentional artificial reefs (modern shipwrecks) in Cyprus (Zenobia) and Lebanon (Alice-B) were evaluated in 2010. Both shipwrecks are at similar depth, type of sea bottom, made of the same material (steel) and were sunk approximately the same period of time. However, Alice-B shipwreck off the coast of Lebanon is constantly exposed to higher levels of nutrients than Zenobia in Cyprus. Significant dissimilarities were observed in the composition, percentage of benthic cover of predominant taxonomic groups and development of the epibenthic communities. Differences in physical and chemical parameters between sides lay mainly in the nutrient and thermal regimes affecting the shipwrecks and most likely bring about the differences in the observed community structure. The results of this study suggest that epibenthic communities could be highly impacted by eutrophication caused by anthropogenic activities, leading to less biodivers

Doppler-free high resolution continuous wave optical UV-spectroscopy on the \mathrm{A}\,^2\Sigma^+ \leftarrow \mathrm{X}\,^2\Pi_{3/2} transition in nitric oxide

We report on Doppler-free continuous-wave optical UV-spectroscopy resolving the hyperfine structure of the \mathrm{A}\,^2\Sigma^+ \leftarrow \mathrm{X}\,^2\Pi_{3/2} transition in nitric oxide for total angular momenta $J_X=1.5-19.5$ on the $\mathrm{oP_{12ee}}$ branch. The resulting line splittings are compared to calculated splittings and fitted determining new values for the molecular constants $b, c, eQq_0$ and $b_F$ for the \mathrm{A}\,^2\Sigma^+ state. The constants are in good agreement with values previously determined by quantum beat spectroscopy.Comment: 8 Pages, 4 figure

Collisional shift and broadening of Rydberg states in nitric oxide at room temperature

We report on the collisional shift and line broadening of Rydberg states in nitric oxide (NO) with increasing density of a background gas at room temperature. As a background gas we either use NO itself or nitrogen (N$_{2}$). The precision spectroscopy is performed by a sub-Doppler three-photon excitation scheme with a subsequent readout of the Rydberg states realized by the amplification of a current generated by free charges due to collisions. The shift shows a dependence on the rotational quantum state of the ionic core and no dependence on the principle quantum number of the orbiting Rydberg electron. The experiment was performed in the context of developing a trace-gas sensor for breath-gas analysis in a medical application

Ultraviolet photodetectors and readout based on a‐IGZO semiconductor technology

In this work, real-time ultraviolet photodetectors are realized through metal–semiconductor–metal (MSM) structures. Amorphous indium gallium zinc oxide (a-IGZO) is used as semiconductor material and gold as metal electrodes. The readout of an individual sensor is implemented by a transimpedance amplifier (TIA) consisting of an all-enhancement a-IGZO thin-film transistor (TFT) operational amplifier and a switched capacitor (SC) as feedback resistance. The photosensor and the transimpedance amplifier are both manufactured on glass substrates. The measured photosensor possesses a high responsivity R, a low response time tRES, and a good noise equivalent power value NEP.Deutsche ForschungsgemeinschaftProjekt DEA

Changing dominance in mixed profession groups:Putting theory into practice

An extended professional identity theory is proposed to enhance interprofessional collaboration. The purpose of this study is to investigate whether comparative feedback on interprofessional interaction can decrease the degree of profession-based dominance and general dominance in mixed profession groups. This observational study comprised a randomized double-blind pretest-posttest control group design with 19 mixed profession groups (10 intervention and nine control groups, each with three dental and three dental hygiene students). All groups received reflective feedback during two consecutive two hour team development meetings. Intervention groups also received comparative feedback. Profession-based dominance concerned the sum of three observation items (conversational turn-taking, dominance and contributing ideas) with a three-point scale: -1 = dental dominance, 0 = no dominance, +1 = dental hygiene dominance. Polychoric correlations confirmed positive associations with the latent trait and an unidimensional underlying structure. Observation items were internally consistent (alpha > .70). General dominance concerned the sum of absolute values of observation items with a minimum value of zero (no dominance) and the maximum value of three (strong dominance). A two-way factorial ANOVA was performed. The results revealed a significant interaction effect with regard to general dominance, F(1,17) = 6.630, p = 0.20 and large effect size (partial eta squared = 0.28). Comparative feedback on interprofessional interaction decreases general dominance in mixed profession groups