Entanglement of dark electron-nuclear spin defects in diamond.

A promising approach for multi-qubit quantum registers is to use optically addressable spins to control multiple dark electron-spin defects in the environment. While recent experiments have observed signatures of coherent interactions with such dark spins, it is an open challenge to realize the individual control required for quantum information processing. Here, we demonstrate the heralded initialisation, control and entanglement of individual dark spins associated to multiple P1 centers, which are part of a spin bath surrounding a nitrogen-vacancy center in diamond.

Atomic-scale imaging of a 27-nuclear-spin cluster using a quantum sensor.

Nuclear magnetic resonance (NMR) is a powerful method for determining the structure of molecules and proteins. Whereas conventional NMR requires averaging over large ensembles, recent progress with single-spin quantum sensors has created the prospect of magnetic imaging of individual molecules. As an initial step towards this goal, isolated nuclear spins and spin pairs have been mapped.

The Photocatalyzed Aza-Henry Reaction of N-Aryltetrahydroisoquinolines: Comprehensive Mechanism, H- versus H-Abstraction, and Background Reactions.

The cross-dehydrogenative coupling (CDC) reaction of N-aryltetrahydroisoquinolines (THIQ) is one of the most exploited photocatalytic transformation and a test reaction for an exceptional variety of catalysts. However, its mechanism remained unclear concerning involved intermediates, reactive pathways of the amine radical cation and the influence of oxygen and the light source. Therefore, nuclear magnetic resonance (NMR), electron spin resonance (ESR) and synthetic methods were combined to provide a comprehensive picture of the reaction mechanism using Ru(bpy)Cl as a photocatalyst under aerobic and anaerobic conditions.

The Photocatalyzed Aza-Henry Reaction of N-Aryltetrahydroisoquinolines: Comprehensive Mechanism, H(•)- versus H(+)-Abstraction, and Background Reactions.

The cross-dehydrogenative coupling (CDC) reaction of N-aryltetrahydroisoquinolines (THIQ) is one of the most exploited photocatalytic transformation and a test reaction for an exceptional variety of catalysts. However, its mechanism remained unclear concerning involved intermediates, reactive pathways of the amine radical cation and the influence of oxygen and the light source. Therefore, nuclear magnetic resonance (NMR), electron spin resonance (ESR) and synthetic methods were combined to provide a comprehensive picture of the reaction mechanism using Ru(bpy)3Cl2 as a photocatalyst under aerobic and anaerobic conditions.

Studies of a photochromic model system using NMR with ex-situ and in-situ irradiation devices.

The switching behavior of a photochromic model system was investigated in detail via NMR spectroscopy in order to improve understanding of the compound itself and to provide ways to obtain insights into composition trends of a photo switchable (polymeric) material containing spiropyran/merocyanine units. In addition to the classical irradiation performed outside the magnet (ex-situ), a device for irradiation inside the NMR spectrometer (in-situ) was tested. Both setups are introduced, their advantages and disadvantages as well as their limits are described and the setup for future investigations of photochromic materials is suggested.

LED-illuminated NMR studies of flavin-catalyzed photooxidations reveal solvent control of the electron-transfer mechanism.

Mechanistic insights into chemical photocatalysis are mainly the domain of UV/Vis spectroscopy, because NMR spectroscopy has been limited by the type of illumination so far. An improved LED-based illumination device can be used to obtain NMR reaction profiles of photocatalytic reactions under synthetic conditions and perform both photo-CIDNP and intermediate studies. Flavin-catalyzed photooxidations of alcohols show the potential of this setup.

LED based NMR illumination device for mechanistic studies on photochemical reactions--versatile and simple, yet surprisingly powerful.

An LED based illumination device for mechanistic studies on photochemical reactions by means of NMR spectroscopy is presented. The LEDs are directly switched by the NMR spectrometer with the help of a one-stage electronic circuit. This allows for continuous or alternatively pulsed operation of the LEDs.

Automated quality evaluation of digital fundus photographs.

Purpose: Retinal images acquired by means of digital photography are often used for evaluation and documentation of the ocular fundus, especially in patients with diabetes, glaucoma or age-related macular degeneration. The clinical usefulness of an image is highly dependent on its quality. We set out to develop and evaluate an automatic method of evaluating the quality of digital fundus photographs.

Measurement of optic disc parameters on digital fundus photographs: algorithm development and evaluation.

Purpose: To develop and evaluate a simple and rapid algorithm for optic disc measurements on digital fundus photographs, relying on the macula-disc centre distance as a reference when converting length expressed in pixels to metric distance.

Methods: Measurements were performed on fundus photographs from 68 normal subjects, acquired using five different cameras. The magnification factor and actual size in mum of 1 pixel was known for only one camera.