TY - JOUR A1 - Trinh, Christopher Q. A1 - Ellis, Simon C. A1 - Bland-Hawthorn, Joss A1 - Lawrence, Jon S. A1 - Horton, Anthony J. A1 - Leon-Saval, Sergio G. A1 - Shortridge, Keith A1 - Bryant, Julia A1 - Case, Scott A1 - Colless, Matthew A1 - Couch, Warrick A1 - Freeman, Kenneth A1 - Löhmannsröben, Hans-Gerd A1 - Gers, Luke A1 - Glazebrook, Karl A1 - Haynes, Roger A1 - Lee, Steve A1 - O'Byrne, John A1 - Miziarski, Stan A1 - Roth, Martin M. A1 - Schmidt, Brian A1 - Tinney, Christopher G. A1 - Zheng, Jessica T1 - Gnosis - the first instrument to use fiber bragg gratings for OH suppression JF - The astronomical journal N2 - The near-infrared is an important part of the spectrum in astronomy, especially in cosmology because the light from objects in the early universe is redshifted to these wavelengths. However, deep near-infrared observations are extremely difficult to make from ground-based telescopes due to the bright background from the atmosphere. Nearly all of this background comes from the bright and narrow emission lines of atmospheric hydroxyl (OH) molecules. The atmospheric background cannot be easily removed from data because the brightness fluctuates unpredictably on short timescales. The sensitivity of ground-based optical astronomy far exceeds that of near-infrared astronomy because of this long-standing problem. GNOSIS is a prototype astrophotonic instrument that utilizes "OH suppression fibers" consisting of fiber Bragg gratings and photonic lanterns to suppress the 103 brightest atmospheric emission doublets between 1.47 and 1.7 mu m. GNOSIS was commissioned at the 3.9 m Anglo-Australian Telescope with the IRIS2 spectrograph to demonstrate the potential of OH suppression fibers, but may be potentially used with any telescope and spectrograph combination. Unlike previous atmospheric suppression techniques GNOSIS suppresses the lines before dispersion and in a manner that depends purely on wavelength. We present the instrument design and report the results of laboratory and on-sky tests from commissioning. While these tests demonstrated high throughput (approximate to 60%) and excellent suppression of the skylines by the OH suppression fibers, surprisingly GNOSIS produced no significant reduction in the interline background and the sensitivity of GNOSIS+IRIS2 is about the same as IRIS2. It is unclear whether the lack of reduction in the interline background is due to physical sources or systematic errors as the observations are detector noise dominated. OH suppression fibers could potentially impact ground-based astronomy at the level of adaptive optics or greater. However, until a clear reduction in the interline background and the corresponding increasing in sensitivity is demonstrated optimized OH suppression fibers paired with a fiber-fed spectrograph will at least provide a real benefit at low resolving powers. KW - atmospheric effects KW - infrared: diffuse background KW - instrumentation: miscellaneous Y1 - 2013 U6 - https://doi.org/10.1088/0004-6256/145/2/51 SN - 0004-6256 VL - 145 IS - 2 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Roth, Martin M. A1 - Löhmannsröben, Hans-Gerd A1 - Kelz, A. A1 - Kumke, Michael Uwe T1 - innoFSPEC : fiber optical spectroscopy and sensing Y1 - 2008 SN - 978-0-819-47228-1 ER - TY - GEN A1 - McQuade, D. Tyler A1 - O'Brien, Alexander G. A1 - Dörr, Markus A1 - Rajaratnam, Rajathees A1 - Eisold, Ursula A1 - Monnanda, Bopanna A1 - Nobuta, Tomoya A1 - Löhmannsröben, Hans-Gerd A1 - Meggers, Eric A1 - Seeberger, Peter H. T1 - Continuous synthesis of pyridocarbazoles and initial photophysical and bioprobe characterization N2 - Pyridocarbazoles when ligated to transition metals yield high affinity kinase inhibitors. While batch photocyclizations enable the synthesis of these heterocycles, the non-oxidative Mallory reaction only provides modest yields and difficult to purify mixtures. We demonstrate here that a flow-based Mallory cyclization provides superior results and enables observation of a clear isobestic point. The flow method allowed us to rapidly synthesize ten pyridocarbazoles and for the first time to document their interesting photophysical attributes. Preliminary characterization reveals that these molecules might be a new class of fluorescent bioprobe. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 246 KW - protein-kinase inhibitors KW - continuous-flow KW - photochemical synthesis KW - light KW - efficient KW - phenanthrenes KW - complexes Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-95214 SP - 4067 EP - 4070 ER - TY - GEN A1 - Cywiński, Piotr J. A1 - Nono, Katia Nchimi A1 - Charbonnière, Loïc J. A1 - Hammann, Tommy A1 - Löhmannsröben, Hans-Gerd T1 - Photophysical evaluation of a new functional terbium complex in FRET-based time-resolved homogenous fluoroassays N2 - A new functional luminescent lanthanide complex (LLC) has been synthesized with terbium as a central lanthanide ion and biotin as a functional moiety. Unlike in typical lanthanide complexes assembled via carboxylic moieties, in the presented complex, four phosphate groups are chelating the central lanthanide ion. This special chemical assembly enhances the complex stability in phosphate buffers conventionally used in biochemistry. The complex synthesis strategy and photophysical properties are described as well as the performance in time-resolved Förster Resonance Energy Transfer (FRET) assays. In those assays, this biotin-LLC transferred energy either to acceptor organic dyes (Cy5 or AF680) labelled on streptavidin or to quantum dots (QD655 or QD705) surface-functionalised with streptavidins. The permanent spatial donor–acceptor proximity is assured through strong and stable biotin–streptavidin binding. The energy transfer is evidenced from the quenching observed in donor emission and from a decrease in donor luminescence decay, both associated with simultaneous increase in acceptor intensity and in the decay time. The dye-based assays are realised in TRIS and in PBS, whereas QD-based systems are studied in borate buffer. The delayed emission analysis allows for quantifying the recognition process and for auto-fluorescence-free detection, which is particularly relevant for application in bioanalysis. In accordance with Förster theory, Förster-radii (R0) were found to be around 60 Å for organic dyes and around 105 Å for QDs. The FRET efficiency (η) reached 80% and 25% for dye and QD acceptors, respectively. Physical donor–acceptor distances (r) have been determined in the range 45–60 Å for organic dye acceptors, while for acceptor QDs between 120 Å and 145 Å. This newly synthesised biotin-LLC extends the class of highly sensitive analytical tools to be applied in the bioanalytical methods such as time-resolved fluoroimmunoassays (TR-FIA), luminescent imaging and biosensing. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 252 KW - acceptors KW - bioanalysis KW - contrast agents KW - europium KW - fluoroimmunoassay KW - labels KW - lanthanide luminescence KW - quantum dots KW - resonance energy-transfer Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-95390 SP - 6060 EP - 6067 ER - TY - JOUR A1 - Beitz, Toralf A1 - Laudien, Robert A1 - Löhmannsröben, Hans-Gerd A1 - Kallies, Bernd T1 - Ion mobility spectrometric investigation of aromatic cations in the gas phase N2 - In this work, ion mobility (IM) spectra of more than 50 aromatic compounds were recorded with a laser-based IM spectrometer at atmospheric pressure. IM spectra of PAH in the laser desorption experiment show a high complexity resulting from the occurrence of monomeric, dimeric, and oligomeric cluster ions. The mobilities of all compounds were determined in helium as drift gas. This allows the calculation of the diffusion cross sections (Omega(calc)) on the basis of the exact hard sphere scattering model and their comparison with the experimentally determined diffusion cross sections (Omega(exp)). Extended Omega(exp)/Omega(calc) and Omega(exp/)mass correlations were performed in order to gain insight into conformational properties of cationic alkyl benzenes and internal rotation of phenyl rings in aromatic ions. This is demonstrated with some examples, such as the evaluation of the dihedral angle of the ions of 9,10- diphenylanthracene, o- and m-terphenyl, and 1,2,3- and 1,3,5-triphenylbenzene. Furthermore, sandwich and T-structures of dimeric PAH cations are discussed. The analysis was extended to oligomeric ions with up to nine monomer units. Experimental evidence is presented suggesting the formation of pi-stacks with a transition toward modified pi-stacks with increasing cluster size. The distance between monomeric units in dimeric and oligomeric ions was obtained Y1 - 2006 UR - http://pubs.acs.org/journal/jpcafh U6 - https://doi.org/10.1021/Jp055335n SN - 1089-5639 ER - TY - JOUR A1 - Hildebrandt, Niko A1 - Charbonniere, Loïc J. A1 - Beck, Michael A1 - Ziessel, Raymond F. A1 - Löhmannsröben, Hans-Gerd T1 - Quantum dots as efficient energy acceptors in a time-resolved fluoroimmunoassay Y1 - 2005 SN - 1433-7851 ER - TY - JOUR A1 - Löhmannsröben, Hans-Gerd T1 - Laser-induced fluorescence (LIF) spectroscopy and laser-based ion mobility (IM) spectrometry for in-situ analysis of contaminated soils Y1 - 2005 ER - TY - JOUR A1 - Löhmannsröben, Hans-Gerd A1 - Lau, Steffen T1 - Isotope selectivity in environmental monitoring : NIR diode laser spectroscopy for isotope-selective sensing of soil-respired carbon dioxide Y1 - 2005 ER - TY - JOUR A1 - Lemke, Matthias A1 - Fernandez-Trujillo, R. A1 - Löhmannsröben, Hans-Gerd T1 - In-situ LIF analysis of biological and petroleum-based hydraulic oils on soil N2 - Absorption and fluorescence properties of 4 hydraulic oils ( 3 biological and 1 petroleum-based) were investigated. In-situ LIF (laser-induced fluorescence) analysis of the oils on a brown sandy loam soil was performed. With calibration, quantitative detection was achieved. Estimated limits of detection were below ca. 500 mg/kg for the petroleum-based oil and ca. 2000 mg/kg for one biological oil. A semi-quantitative classification scheme is proposed for monitoring of the biological oils. This approach was applied to investigate the migration of a biological oil in soil- containing compartments, namely a soil column and a soil bed Y1 - 2005 SN - 1424-8220 ER - TY - JOUR A1 - Engelhard, Sonja A1 - Löhmannsröben, Hans-Gerd A1 - Schael, Frank T1 - Quantifying ethanol content of beer using interpretive near-infrared spectroscopy N2 - On the basis of absorption measurements in the near-infrared (NIR) spectral range, a new method for the quantification of the ethanol content of beer is presented. Instead of the multivariate calibration models most commonly employed in NIR spectroscopic works, we use interpretive difference spectroscopy: Two wavelengths are selected according to the assignment of the absorption bands of the main substances of content of beer in the NIR region, and the difference between the absorbances at these wavelengths is used for ethanol quantification. Absorption spectra of the dominating beer ingredients are discussed and the calibration procedure with ethanol/water mixtures is shown. Robustness against the carbohydrate content of beer samples was demonstrated by analyzing solutions of ethanol and maltose in water. Validation of the method was performed with various beer samples with an ethanol concentration range between 0.5 and 7.7 vol %. The pertinent advantage of the procedure developed in this work is the indication that the results are independent from seasonal variations of the ingredients, which is of high interest for products with natural ingredients such as beer Y1 - 2004 SN - 0003-7028 ER -