Die vorliegende Arbeit befasst sich mit der Untersuchung von Metall-Halbleiter-Metall ultravioletten Photodioden basierend auf Dünnschichten der weitbandlückigen Halbleitern Magnesiumzinkoxid (Mg,Zn)O und Galliumindiumoxid (In,Ga)2O3. Die Arbeit behandelt zwei inhaltliche Schwerpunkte. Der erste Schwerpunkt liegt auf Herstellung, Entwicklung und Charakterisierung der wellenlängenselektiven (Mg,Zn)O-Photodioden bei Erhaltung der Wurtzitstruktur in UVA und UVB Spektralbereichen. Dabei wurde eine integrierte optische Filterschicht mit einem höheren Mg-Gehalt verwendet, die einen Teil der von der Rückseite einfallende Strahlung absorbieren kann. Um die Selektivität der Absorptionskante und die Bandbreite des Detektoren abzustimmen, wurden unterschiedliche Kombinationen der Mg-Gehalte in den Schichten untersucht. Weiterhin wurde der Ansatz eines kontinuierlichen Kompositionsgradienten mittels großflächig gepulster Laserabscheidung genutzt, um monolithisch mehrkanalig schmalbandige Photodioden zu realisieren. Dadurch konnten die kontinuierliche Verschiebung der Absorptionskante von beiden Activ- und Filterschichten sowie die Photodetektion mit minimierter und einheitlicher spektraler Auflösung innerhalb von einem 2 inch im Durchmesser Wafer ermöglicht werden. Der zweite Schwerpunkt konzentriert sich auf die Untersuchung der wellenlängenselektiven Photodioden basierend auf Si-dotierten (In,Ga)2O3 Dünnschichten mittels der kontinuierlichen Kompositionsgradienten durch unterschiedliche Variation des Indium-Gehaltes. Die Absorptionskante der (In,Ga)2O3 Dünnschichten konnte von UVA bis zum UVC Spektralbereich abgestimmt werden. Die chemische und strukturelle Eigenschaften der Dünnschichten wurden mittels Kathodolumineszenzmikroskop, energiedispersive Röntgenspektroskopie and Röntgenbeugung studiert. Die elektrischen Eigenschaften der Schottky-Kontakte wurden mit hochpräzisen Strom-Spannungs-Messung bestimmt. Die Untersuchung der Absorptionskante sowie der Effzienz der Photodioden geschieht mittels spektralaufgelöster Photostrommessungen.

Ultraviolet colouration of flowers varies both among and within species. The significance of these patterns and differences among them was usually associated with a visual per- ception of pollinators. In this study we examine the variation of marsh marigold's (Caltha palustris) bull's-eye pattern on a basis of 289 observed individuals from 32 distinct locati- ons. The variation of this pattern is shown to be quite large within separate locations and the pattern is predictably changing according to latitude. This trend of darker colouration towards the equator is an another example of a more widely understood Gloger's rule in the plant kingdom. The effect of ultraviolet radiation appears to be one of the most likely causes of this phenomenon. Hereafter we analyse the weakness of this explanation, the gaps in current knowledge and propose possible directions of further research. Keywords: ultraviolet, bull's-eye, marsh marigold, Caltha palustris, Gloger's rule

Polyaromatic hydrocarbons (PAHs) are contaminants synthesized through incomplete combustion of carbon based substances. PAHs are known to be photodynamic and toxicity increases exponentially when in contact with ultraviolet radiation (UV). The effect of UV absent recovery periods and potential for latent toxicity during photo-induced toxicity are previously unknown and are not included within the toxicity model. Results of equal interval tests further support the current reciprocity model as a good indicator of PAH photo-induced toxicity. Interval test results also indicate a possible presence of time-dependent toxicity and recovery thresholds and should be included into toxicity risk assessments. Moreover, results of latent effects assays show that latent mortality is a significant response to PAH photo-induced toxicity and should be included into toxicity risk assessments. The present research demonstrates that UV exposure time rate is a significant driving force of PAH photo-induced toxicity.

Les lasers solides émettant dans l'UV sont l'objet de nombreux efforts de recherche. Ainsi, deux cristaux non linéaires ont été développés et caractérisés pour réaliser la conversion de fréquences laser dans le domaine UV : Ca5(BO3)3F (CBF) et YAl3(BO3)4 (YAB). Concernant les cristaux de CBF, l'influence des gradients thermiques ainsi que de nouveaux flux ont été étudiés en vue d'améliorer la qualité cristalline. La génération du troisième harmonique à 343 nm en type II a été réalisée pour la première fois dans CBF. 300 mW correspondant à un rendement ? (1030 ' 343 nm) = 1,5 % ont été obtenus. L'utilisation de flux à base de LaB3O6 a permis la synthèse de cristaux de YAB par la méthode TSSG. Les propriétés physiques, structurales ainsi que les défauts de ces cristaux ont été caractérisés. De bonnes performances ont été obtenues dans le cadre de la génération du quatrième harmonique à 266 nm puisqu'un rendement de conversion ? (1064 ' 266 nm) = 12,2 % a été atteint. / This PhD study is devoted to the growth and characterization of two promising NLO crystals for UV laser light generation : Ca5(BO3)3F (CBF) and YAl3(BO3)4 (YAB). Concerning CBF, the influence of thermal gradients and new fluxes have been studied in order to improve the crystal quality. The third harmonic generation at 343 nm in CBF is demonstrated for the first time. 300 mW of average power and 1,5 % conversion efficiency from 1030 to 343 nm have been obtained. The use of the flux LaB3O6 allows the growth YAB crystals by TSSG method. Structural and physical properties as well as extended defects and impurities of these crystals have been characterized. Fourth harmonic generation at 266 nm was performed in YAB and 12,2 % conversion efficiency from 532 to 266 nm has been obtained.

Indiana University-Purdue University Indianapolis (IUPUI) / With bombings in the United States on the rise for the first time since 2016, the detection and identification of explosives remains of pertinent interest to law enforcement agencies. This work presents two soon-to-be published research articles that focus on the detection and identification of explosives by both chemical instrumentation and canines. The first article, Quantitative Analysis of Smokeless Powder Particles in Post-Blast Debris via Gas Chromatography/Vacuum Ultraviolet Spectroscopy (GC/VUV), utilizes gas chromatography/vacuum ultraviolet spectroscopy (GC/VUV) to determine the difference in chemical composition of two smokeless powders in both pre- and post-blast conditions. The compounds of interest in this study were nitroglycerin, 2,4- dinitrotoluene, diphenylamine, ethyl centralite, and di-n-butyl phthalate. Concentration changes between pre- and post-blast smokeless powder particles were determined as well as microscopic differences between pre- and post-blast debris for both smokeless powders in all devices. To our knowledge, this is the first use of GC/VUV for the quantification of explosives. The second article, An Odor-Permeable Membrane Device for the Storage of Canine Training Aids, proposes the use of an odor-permeable membrane device (OPMD) as a standardized storage method for canine training aids. It is hypothesized that the OPMD would minimize cross-contamination between training aids, and that the OPMD could be used for canine training as well as storage. The goal of this research is to use flux and evaporation rate to quantify the explosive odor that escapes from the OPMD compared to unconfined explosives. Preliminary data suggests that there is an exponential relationship between relative boiling point and evaporation rate. It has been determined that compounds with higher boiling points have lower evaporation rates than compounds that have lower boiling points. The materials studied thus far are known odor compounds produced by explosive formulations. These include nitromethane, nitroethane, 1- nitropropane, r-limonene, and toluene.

We report on ultraviolet photodiodes with integrated optical filter based on the wurtzite (Mg,Zn)O thin films. Tuning of the bandgap of filter and active layers was realized by employing a continuous composition spread approach relying on the ablation of a single segmented target in pulsed-laser deposition. Filter and active layers of the device were deposited on opposite sides of a sapphire substrate with nearly parallel compositional gradients. Ensure that for each sample position the bandgap of the filter layer blocking the high energy radiation is higher than that of the active layer. Different oxygen pressures during the two depositions runs. The absorption edge is tuned over 360 meV and the spectral bandwidth of photodiodes is typically 100 meV and as low as 50 meV.

The ionospheric response to solar EUV variability during 2011 - 2014 is shown by an EUV proxy based on primary ionization calculations using combined solar spectra from SDO/EVE and SolACES on board the ISS. The daily proxies are compared with global mean TEC analyses. At time scales of the solar rotation and longer, there is a time lag between EUV and TEC variability of about one to two days, indicating dynamical processes in the thermosphere/ionosphere systems. This lag is not seen at shorter time scales. When taking this delay into account the TEC variance at the seasonal and short-term time scale explained by EUV variations increases from 71% to 76%. / Die ionosphärische Antwort auf Variationen des solaren EUV im Zeitraum 2011-2014 wird anhand eines Proxys dargestellt, welcher die primäre Ionisation auf der Basis gemessener solare EUV-Spektren beinhaltet. Die täglichen Werte werden mit Analysen des global gemittelten Gesamtelektronengehalts verglichen. Auf Zeitskalen der solaren Rotation und länger findet sich eine Zeitverzögerung zwischen der EUV-Variation und des derjenigen des Gesamtelektronengehalts von ein bis 2 Tagen, welche auf dynamische Prozesse im System Thermosphäre/Ionosphäre hinweist. Die Verzögerung ist auf kurzen Zeitskalen nicht zu sehen. Wenn diese Verzögerung berücksichtigt wird, erhöht sich die durch EUV-Variationen erklärte Varianz des Elektronengehalts von 71% auf 76%.

We present a. survey of high dispersion UV and optical spectra of Herbig Ae/Be (HAeBe) and related stars. We find accreting, circumstellar gas over the velocity range +100 to +400 km s-1, and absorption profiles similar to those seen toward β Pic, in 36% of the 33 HAeBe stars with IUE data as well as in 3 non-emission B stars. We also find evidence of accretion in 7 HAeBe stars with optical data only. Line profile variability appears ubiquitous. As a group, the stars with accreting gas signatures have higher ν sin i than the stars with outflowing material, and tend to exhibit large amplitude (≥ 1m) optical light variations. All of the program stars with polarimetric variations that are anti-correlated with the optical light, previously interpreted as the signature of a dust disk viewed close to equator-on, also show spectral signatures of accreting gas. These data imply that accretion activity in HAeBe stars is preferentially observed when the line of sight transits the circumstellar dust disk. Our data imply that the spectroscopic signatures of accreting circumstellar material seen in β Pic are not unique to that object, but instead are consistent with interpretation of β Pic as a comparatively young A star with its associated circumstellar disk.

Ultraviolet spectra obtained with Hubble Space Telescope (HST) of two Mira-type variable stars, R Leo and R Hya, are presented, along with analysis providing information on their outer atmospheres. These high-dispersion spectra were taken with the Goddard High Resolution Spectrograph (HRS) in two spectral regions: 2320-2368 Å to record the C II] (UV0.01) multiplet and 2785-2835 Å to obtain the Mg II h and k lines. The R Hya spectrum was obtained at visual light phase 0.26 and shows a Mg II spectrum that is very clean, showing clear evidence for the overlying circumstellar absorption from Fe I (UV3) and Mn I (UV1) over the k line. The fluoresced Fe I (UV44) feature at 2824 Å is plainly visible in this spectrum, whereas past International Ultraviolet Explorer (IUE) observations of Mira variables at high dispersion were unable to record this feature. Remarkably, the newly identified fluoresced Fe I (UV45) feature near 2807 Å is seen in this spectrum. Until now, this line has been seen only in cool carbon stars with HST/HRS. This line is pumped by the thin C II] (UV0.01) emission line at 2325.5 Å. Two of the strongest C II] (UV0.01) lines near 2325 Å are plainly seen in this spectrum. This region of the spectrum, however, is dominated by the Si II] (UV0.01) line near 2335 Å, in contrast to that observed in the carbon stars and the non-Mira oxygen-rich red giant stars. Very weak Mg II lines are seen in the R Leo spectrum at phase 0.12. At this phase, these lines are typically absent in IUE spectra. Velocity shifts of emission features in the UV spectra of Mira variables are consistent with previously published hydrodynamic models of these stars. These velocities indicate, however, that the C II] (UV0.01) emission lines are not formed in the same atmospheric layers as the Mg II emission. The electron density deduced from the C II] (UV0.01) multiplet is ∼109 cm-3. Finally, the temperature-density structure of the semi-regular variable carbon stars is similar to the oxygen-rich Mira variables-both are hydrodynamic in nature; however, the carbon stars macroscopic velocity fields are not identical to the Mira stars in the atmosphere layers between the Mg II emission region and the circumstellar shell.

We have conducted a statistical analysis of the ultra-luminous X-ray point sources (ULXs; L X ≥ 10 39 ergs -1) in a sample of galaxies selected from the Arp Atlas of Peculiar Galaxies. We find a possible enhancement of a factor of 2-4 in the number of ULXs per blue luminosity for the strongly interacting subset. Such an enhancement would be expected if ULX production is related to star formation, as interacting galaxies tend to have enhanced star formation rates on average. For most of the Arp galaxies in our sample, the total number of ULXs compared to the far-infrared luminosity is consistent with values found earlier for spiral galaxies. This suggests that for these galaxies, ULXs trace recent star formation. However, for the most infrared-luminous galaxies, we find a deficiency of ULXs compared to the infrared luminosity. For these very infrared-luminous galaxies, active galactic nuclei may contribute to powering the far-infrared; alternatively, ULXs may be highly obscured in the X-ray in these galaxies and therefore not detected by these Chandra observations. We determined local UV/optical colors within the galaxies in the vicinity of the candidate ULXs using Galaxy Evolution Explorer UV and Sloan Digitized Sky Survey optical images. In most cases, the distributions of colors are similar to the global colors of interacting galaxies. However, the u - g and r - i colors at the ULX locations tend to be bluer on average than these global colors, suggesting that ULXs are preferentially found in regions with young stellar populations. In the Arp sample there is a possible enhancement of a factor of 2-5 in the fraction of galactic nuclei that are X-ray-bright compared to more normal spirals.