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Dissertation
Interatomic Coulombic decay in noble gas clusters of varying sizes investigated by photon-induced (dispersed) fluorescence spectrometry
(2018-06-06)
The main topic of this thesis is to study experimentally an ultrafast and efficient non radiative mechanism – the well-known interatomic Coulombic decay (ICD) – in noble gas clusters by employing fluorescence spectrometry technique in combination with synchrotron radiation. Using Neon clusters as prototype systems, a special variety of ICD, termed resonant ICD (RICD), has been investigated by a selective excitation of one component of the cluster and for different mean cluster sizes. The first part of the thesis was ...
Dissertation
Surface modifications of nanocrystalline diamond films and their functionalization with phthalocyanines
(2016-06-30)
Boron-doped diamond is a promising electrode material for a number of applications providing efficient carrier transport, a high stability of the electrolytic performance with time, a possibility for dye-sensitizing with photosensitive molecules, etc. It can be functionalized with electron donor molecules, like phthalocyanines or porphyrins, for the development of light energy conversion systems. For effective attachment of such molecules, the diamond surface has to be modified by plasma- or photo-chemical processes ...
Dissertation
Fabrication of diamond nanostructures and investigation of the imbedded NV centers
(2015-02-24)
Diamant ist ein Material mit vielen außerordentlichen Eigenschaften, die ihn zu einem äußerst vielversprechenden Kandidaten für Anwendungen in Wissen-schaft und Technik machen. In den letzten Jahren wurde Diamant häufig als einzigartige Plattform für neue Anwendungen beispielsweise in der Quanteninformationstechnologie (QIT) oder in der Magnetometrie im Nanometermaßstab eingesetzt, wobei einer der wichtigsten lumineszierenden Gitterdefekte im Diamantgitter eingesetzt wird. Dabei handelt es sich um die sogenannten ...
Dissertation
Hochsensible Intrakavitäts-Absorptionsspektroskopie von Spurengasen unter Ausnutzung der Modenkonkurrenz eines Halbleiterlasers
(2015-02-12)
Eine Halbleiterdiode mit externer Kavität wird um eine Messzelle speziell für Gase erweitert. Diese erlaubt Absorptionsmessungen einer exakt definierten Menge von Gas unter kontrollierten Temperatur- und Druckbedingungen. Es werden konzentrationsabhängige Absorptionsmessungen mit Propofol durchgeführt. Als Ergebnis werden effektive Pfadlänge, Bestimmungs- und Nachweisgrenze berechnet und der Beweis erbracht, dass beide im System anschwingenden Moden in Konkurrenz zueinander stehen. Weiterhin wurde eine ausgeprägte ...
Dissertation
Optical Characterization of Organic Gain Materials for UV-emitting Hybrid Complex Coupled VCSELs
(2014-03-26)
In this thesis, optical gain measurement setup based on variable stripe length method is designed, implemented and improved. The setup is characterized using inorganic and organic samples. The optical gain of spiro-quaterphenyl is calculated and compared with measurements from the setup. Films with various thicknesses of spiro-quaterphenyl, methoxy-spiro-quaterphenyl and phenoxy-spiro-quaterphenyl are deposited by a vacuum vapor deposition technique forming asymmetric slab waveguides. The optical properties, laser ...
Dissertation
Model Calculations for Characterisation and Implementation of Vertical Thin-Layer Structures with Distributed Cavity Mode for Filter and Laser Applications
(2018-04-11)
This work focusses on the approach of optical thin-layer filters with distributed cavity mode. Fabry-Pérot filters own a single cavity layer in the centre of the stack. In contrast, with chirped filter approach the cavity thickness is distributed over several layers. Model calculation results are applied to characterise the properties of the spectrum and the electric field of chirped filters. The aim of distributing the cavity within the filter stack is to distribute the electric field in the resonance case (transmission ...
Dissertation
Patent DE10 2004 037 519 B4 “Sensor Process and Device for Determining a Physical Value“. A Proof of Concept
(2010-06-11)
At present, a fraction of 0.1 - 0.2% of the patients undergoing surgery become aware during the process. The situation is referred to as anesthesia awareness and is obviously very traumatic for the person experiencing it. The reason for its occurrence is mostly an insufficient dosage of the narcotic Propofol combined with the incapability of the technology monitoring the depth of the patient’s anesthetic state to notice the patient becoming aware.
A solution can be a highly sensitive and selective real time monitoring ...
Dissertation
Highly Sensitive Sensor Based On Intracavity Laser Absorption Spectroscopy By Means of Relative Intensity Noise
(2011-01-07)
This thesis concerns with the main aspects of medical trace molecules detection by means of intracavity laser absorption spectroscopy (ICLAS), namely with the equirements for highly sensitive, highly selective, low price, and compact size sensor. A novel two modes semiconductor laser sensor is demonstrated. Its operation principle is based on the competition between these two modes. The sensor sensitivity is improved when the sample is placed inside the two modes laser cavity, and the competition between the two modes ...
Dissertation
Optical Sensor Array based Nanospectrometer: Fabrication of high resolution 3D NanoImprint master templates and bonding of Fabry-Pérot filter array onto photodetector array
(2017-05-11)
In the field of optical spectroscopy, spectrometers are high resolution optical sensors that have emerged as a platform for a wide range of application fields. Commercially available spectrometers are bulky and expensive. Hence, this limits its integration into modern mobile and wearable devices. To overcome this limitation, miniaturization of spectrometers is an interesting target for a wide range of emerging applications. The most attractive concept of fabricating miniaturized spectrometers is the Fabry-Pérot filter ...
Dissertation
Intrakavitäts-Absorptionsspektroskopie von Spurengasen mit hoher Sensitivität und Selektivität auf Basis konkurrierender Moden eines Halbleiterlasers
(2016-08-30)
Die Validität des Sensorkonzeptes aus dem Patent von Prof. H. Hillmer wird unter Verwendung einer gasförmigen Testsubstanz gezeigt. Zu diesem Zweck wird ein bestehender Messaufbau durch zahlreiche Verbesserungen optimiert. Die optischen Eigenschaften der verwendeten Komponenten und der resultierenden modifizierten Aufbauten werden dargelegt.
Die bisherigen faserbasierter Messaufbauten werden zu einem symmetrischen Messaufbau mit verbesserter spektraler Auflösung und vereinfachter Handhabung erweitert. Die Vorlaufzeiten, ...