Lidar measurements of atmospheric constituents

The advent of depth-resolving, remote measurement techniques for the determination of atmospheric constituents added a new dimension to the investigation of atmospheric phenomena. In the present paper optical, or lidar, techniques suited for this purpose are reviewed. After a presentation of the processes used and the algorithms necessary to extract the interesting information from the optical return signals, a few considerations about the necessary instrumentation are presented. For illustration, one example is shown of results obtained with elastic backscatter, differential absorption and scattering, Raman lidar, and Raman DIAL. Of the numerous new developments in actual progress, one example, BELINDA, has been chosen that in a way marks the borderline between elastic backscatter and differential absorption lidar. (orig.)Available from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Biotest-geleitete chemische Analyse von Sedimenten

In the scope of this thesis a procedure for the bioassay-directed chemical analysis of contaminated sediments was developed. It comprises the detection of acute toxic and mutagenic effects and the identification of the chemicals responsible for them. Porewater samples and eluates, respectively, as well as organic sediment extracts were investigated for acute and mutagenic effects using the two bacterial bioassays Microtox "t"r"a"d"e"m"a"r"k and Mutatox "t"r"a"d"e"m"a"r"k. All extracts and porewater samples were also examined by a non-target screening analysis by HPLC/MS or GC/MS. If a sample was toxic, it was fractionated. The toxicity was measured again in the fractions and the screening analysis was repeated. Moderately contaminated sediment samples from the Rivers Elbe, Saale and Rhine as well as highly contaminated samples from Hamilton Harbour (Canada), Hamburger Hafen and the River Bilina (Czech Republic) were investigated that way. The extracts from the moderately contaminated sites only showed minor effects, which were not put down to particular chemicals. In the samples form the highly contaminated sites compounds like PAH or bisphenol A were responsible for the extract toxicities. The effects were reproduced and verified by the measurement of single reference compounds and mixtures in the bioassays. (orig.)Available from TIB Hannover: RA 3251(2000/12) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Entwicklung eines dualen Empfangskanals fuer das DAS-Lidarsystem ARGOS

The present work describes the concept, setup and testing of a dual receiving channel for the UV-lidar system ARGOS which measures ozone and sulfur dioxide in the troposphere by use of the differential absorption and scattering (DAS) technique. A photon counting system for the new long-range channel was assembled and characterized with regard to detector voltage, discrimination level, dark counts, maximum count rate and signal-induced noise. The method of variable electrooptic signal compression was adapted to the ultraviolet spectral region. Extensive laboratory tests indicate the applicability of electrooptic signal compression within the ultraviolet spectral region to the protection of the detection system against high signal intensities from short distances and to the expansion of the range of the second channel to short distances. Delays down to 600 #mu#s between measurement and reference signal proved to be practicable. Variable high-voltage driver circuits for large-aperture electrooptic modulators were developed. Tests confirmed that the circuits do not give rise to a considerable error in the DAS measurements. First atmospheric lidar measurements indicate that the range of the second channel will reach up to the top of the troposphere and, at its lower end, has large overlap with the range of the first channel. (orig.)51 refs.Available from TIB Hannover: RA 3251(96/E/25) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Resonante Mehr-Photonen-Ionisations-Flugzeitspektroskopie (REMPITOF) an Quecksilber Entwicklung und Aufbau eines Geraetes zur Spurenanalytik

This work describes a device for trace analysis by Resonant Enhanced Multiphoton Ionization (REMPI) with subsequent Time-Of-Flight (TOF) analysis of the ionization products. An important feature of the device is the coating of all surfaces relevant for the ion optics with spongiform, chemically inert titanium nitride, providing high surface conductivity and stable operation. The spectroscopic investigations include the determination of ionization efficiencies of ten different excitation/ionization schemes of elemental mercury. It turns out that no efficient ionization is possible unless the first excitation step proceeds through the 6"3P_1 level. An improvement by a factor of 40 with respect to the most efficient excitation-ionization path so far described is obtained when ionization is carried out via an autoionization state populated from the 6"3P_1 state. Pulsed extraction fields are used to examine the sample under field-free conditions. High-lying Rydberg states can thus be studied. The hyperfine split of the Rydberg spectra is resolved. Finally it is shown that single-shot isotope-specific trace-gas data can be obtained, proving the suitability of the method for practical applications in trace-level analysis. (orig.)Available from TIB Hannover: RA 3251(97/E/57) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Fernmessung aromatischer Kohlenwasserstoffe in Flugzeugabgasen mittels Fluoreszenz

A feasibility study has been carried out on ground-based optical remote measurements of aromatic hydrocarbons in aircraft wakes by fluorescence. A fluorescence lidar has been outlined, and signal power has been estimated for expected hydrocarbon concentrations; the quantities important for the fluorescence technique have been evaluated. It is shown that the maximum measurement range of a fluorescence lidar can be expected to be less than 1 kn, ground-bades measurements of aromatic compounds at cruising altitudes are not feasible. Because of environment-dependent fluorescence quantum yields and the influence of ozone and aerosols on atmospheric transmission, a quantitative evaluation of the fluorescence signals is impossible. The cost of a fluorescence lidar is considerable. In conclusion, the development of such a system cannot be recommended. DIAL measurements of aromatic hydrocarbons appear more promising. This study was carried out in spring 1993SIGLEAvailable from TIB Hannover: RA 3251(99/E/27) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Reagenzfreisetzung durch Kernspurfilter - Transportmechanismen und Anwendungsmoeglichkeiten

An automated preparation of standard and low concentrated solutions by the application of an automated dilution system avoided losses in precision, time and reproducibility. This thesis improves the applicability and handling of a reagent delivery system for routine analysis. Models of transport processes were developed describing the mass transport through track-etch membrane filters and micro channels. The influence of several system parameters such as transmembrane pressure, temperature, substance and concentration of the stock solution on the dilution factor was evaluated. It was shown, that the precision of the automated dilution using the reagent delivery system is comparable to the precision of manual dilution with flasks and pipettes and other automated dilution systems. Several examples of applications demonstrated the efficiency and possible applicabilities of the reagent delivery system. (orig.)Available from TIB Hannover: RA 3251(2000/4) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Huellstromkuehlung - ein Beitrag zur Tieftemperaturspektroskopie umweltrelevanter Gase und Molekuelcluster im Infraroten

The present work describes concept, setup and testing of enclosive flow cooling which is a novel cooling technique developed for infrared absorption spectra simplification of supercooled gases. The method proved to be an effective alternative to the common supersonic flow cooling and has a much higher optical absorption efficiency. The spectral simplifications (suppression of hot bands, narrowing of vibration bands and single lines, decrease of spectral line number density and superposed fundamental bands) of CO_2, CH_4, CHF_3 and CH_3CHO were investigated around 100 K. The results confirm the theoretical predictions. Compared to room temperature, an increase of both optical absorption efficiency and gas mixture detection selectivity of nearly one order of magnitude is demonstrated. The cooling method offers applications in generation and spectroscopy of molecular clusters. Clusters of CO_2, CHF_3 and CH_3CHO were examined. Furthermore, the basic concept for using the method with liquid helium cooling in the temperature range around 4 K is described which will have a higher optical absorption efficiency by an additional factor of 100. (orig.)SIGLEAvailable from TIB Hannover: RA 3251(95/E/35) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Kontamination von Grundwasser durch Ruestungsaltlasten - Entwicklung analytischer Methoden und Bewertung der Belastung am Beispiel einer ehemaligen Sprengstoffabrik

Areas of former ammunition plants are often highly contaminated by various explosives and accompanying compounds. This thesis provides a survey on modern analytical methods for the determination of the complete range of these pollutants. In addition to the development of a powerful concept for chromatographic separation and sensitive detection, different micro-methods for efficient sample preparation were developed and applied. Analyses of the field samples showed that the determined pollutants correlated very well with the former use of the plant. Examinations over a period of two years indicated that the contaminants are spread through the groundwater of threaten the whole adjoining area. Final measurements on acute toxicity and mutagenicity of the samples showed that the quality of the groundwater is highly endangered pollutants. (orig.)Available from TIB Hannover: RA 3251(98/E/59) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Entwicklung einer Ultraschall-Levitations-Apparatur fuer die Probenvorbereitung in der Mikro- und Spurenanalyse

An acoustic levitation device for microscale sample preparation is described. Sample volumes of a few microliters can be handled in a contactless way and protected from the loss of analyte through adsorption, memory effects and contamination from container walls. Sample enrichment, derivatization and liquid/liquid-extraction can be performed in a single levitated droplet as part of the sample pretreatment in an analytical procedure. The levitation device follows a modular design and consists of an acoustic levitator, droplet size measurement, solvent and reagent supply and experiment control and documentation. The applicability of the experimental setup is demonstrated by the enrichment of hexachlorbenzene dissolved in isooctane and the derivatization of butyltin compounds with sodium tetraethylborate in water under subsequent extraction of the prealkylated products into hexane in droplets of 3 to 5 #mu#L volume as sample preparation for a gas-chromatographic separation. (orig.)SIGLEAvailable from TIB Hannover: RA 3251(99/E/75) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Ueber die Moeglichkeiten zum Nachweis von superschweren Elementen (SHE) in der Erdkruste mit der hochenergetischen Synchrotron-Strahlung und mit der Massenspektrometrie

There are many indications for the existence of superheavy elements (SHE) in the Earth's crust. The appropriate detection methods are X-ray fluorescence (XRF) using the high energy synchrotron radiation and the mass spectrometry. The characteristic X-rays of each element up to Z >120 (corresponding binding energy of the K-electrons E_b >230 keV) can be precisely excited with synchrotron XRF. Up to now, the XRF with high energy photons has never been applied to the quest for SHE. New methods of mass spectrometry eg using resonance ionization (RIMS) are promising to detect unambiguously atomic masses about 300 in solid matrices. It is proposed to restart the quest for SHE in the nature. Finding a SHE in the Earth's crust would be very important, because of what it will tell us about the origin of the elements eg about the nucleosynthesis during a super nova explosion, the structure of the atomic nuclei and the site of SHE in the periodic table of elements. (orig.)Es gibt viele Hinweise auf die Existenz von superschweren Elementen in der Erdkruste. Als Nachweismethoden eignen sich die Roentgen-Fluoreszens mit der hochenergetischen Synchrotron-Strahlung (RFA) und die Massenspektrometrie. Mit der RFA kann die charakteristische Roentgen-Strahlung der Elemente bis Z>120 (zugehoerige Bindungsenergie der K-Elektronen E_b > 230 keV) gezielt fuer jedes Z angeregt werden. Diese Analysenmethode ist in dem angegebenen Energiebereich bisher noch nicht fuer die Suche nach superschweren Elementen eingesetzt worden. Neue Verfahren zur Massenspektrometrie z.B. die Resonanzionisations-Massenspektrometrie (RIMS) muessen Atommassen um 300 in jeder Matrix eindeutig nachweisen koennen. Es wird vorgeschlagen, mit diesen Methoden die Suche nach SHE in der Natur wieder aufzunehmen. Der Nachweis von SHE in der Natur wuerde die Kenntnisse ueber die Entstehung der Elemente z.B. die Nukleosynthese waehrend einer Supernova Explosion eines Sterns, den Aufbau der Atomkerne und die Struktur des Periodensystems der Elemente in entscheidenden Punkten ergaenzen. (orig.)Available from TIB Hannover: RA 3251(2001/18) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman