P. Reichart

Implantation of labelled single nitrogen vacancy centers in diamond using N15

Nitrogen-vacancy (NV−) color centers in diamond were created by implantation of 7 keV N15(I=1∕2) ions into type IIa diamond. Optically detected magnetic resonance was employed to measure the hyperfine coupling of single NV− centers. The hyperfine spectrum from NV−15 arising from implanted N15 can be distinguished from NV−14 centers created by native N14(I=1) sites. Analysis indicates 1 in 40 implanted N15 atoms give rise to an optically observable NV−15 center. This report ultimately demonstrates a mechanism by which the yield of NV− center formation by nitrogen implantation can be measured.

Characterization of three-dimensional microstructures in single-crystal diamond

We report on the Raman and photoluminescence characterization of three-dimensional microstructures fabricated in single crystal diamond with a Focused Ion Beam (FIB) assisted lift-off technique. The fabrication method is based on MeV ion implantation, followed by FIB micropatterning and selective chemical etching. In a previous publication we reported on the fabrication of a micro-bridge structure exhibiting waveguiding behavior [P. Olivero, S. Rubanov, P. Reichart, B. Gibson, S. Huntington, J. Rabeau, Andrew D. Greentree, J. Salzman, D. Moore, D. N. Jamieson, S. Prawer, Adv. Mater., 17 (20) (2005) 2427]. In the present work, Raman and photoluminescence spectroscopies are employed to characterize the structural quality of such microstructures, particularly as regards the removal of residual damage created during the machining process. Three-dimensional microstructures in high quality single crystal diamond have many applications, ranging from integrated quantum-optical devices to micro-electromechanical assemblies.

Coherent population trapping in diamond N-V centers at zero magnetic field.

All-optical coherent population trapping is possible in nitrogen-vacancy centers in diamond at zero magnetic field. This should allow for simpler implementations of potential devices involving optical manipulation of electron spins.

Critical components for diamond-based quantum coherent devices

The necessary elements for practical devices exploiting quantum coherence in diamond materials are summarized, and progress towards their realization documented. A brief review of future prospects for diamond-based devices is also provided.

Application of Raman spectroscopy to quantify trace water concentrations in glasses and garnets

Abstract We present a new technique for the quantification of water in glasses down to the parts per million level, using confocal microRaman spectroscopy with the recently developed “Comparator Technique.” To test this method, we used a suite of glasses and gemstone-quality garnets with varying chemical compositions. Water contents were independently determined with proton-proton (pp) scattering and infrared (IR) spectroscopy. Moreover, water concentrations obtained for the garnets were compared to data from a study by Maldener et al. (2003) using nuclear reaction analysis (NRA). For each sample, we recorded Raman spectra in the frequency range from 3100 to 3750 cm-1 and standardized them using an independently well-characterized glass. In this paper, we demonstrate the usefulness of this technique for quantifying water concentrations in natural and synthetic glass samples and garnets, and verify its adaptability for concentrations from 40 wt ppm up to 40 wt% H2O. However, in the case of absorbing material (e.g., Fe-bearing samples), the suggested method needs to be modified to overcome problems due to heating and melting of those phases. Furthermore, we propose an integrated molar absorption coefficient for water in quartz glass, εitot = 72 000 ± 12 000 Lmol-1H₂Ocm-2, for quantitative IR spectroscopy that is higher than a previously reported value of Paterson (1982) or that predicted by the general calibration trend determined by Libowitzky and Rossman (1997).

The Munich microprobe SNAKE: First results using 20 MeV protons and 90 MeV sulfur ions

The scanning ion microprobe called Superconducting Nanoscope for Applied nuclear (Kern) physics Experiments (SNAKE) is taken into operation at the Munich 15 MV tandem accelerator. During the first experiments 16 and 20 MeV protons as well as 90 MeV 32S ions were used to test all equipments. With a reduced divergence of the beam, an overall lateral resolution of 700 nm was achieved by scanning a gold grid with a focused 90 MeV sulfur beam and detecting transmitted ions. However, some field distortions at full acceptance of the lens were detected which derive from mechanical problems at higher coil currents. In addition to the beam characterisation experiments several new detector systems were tested. Analysing the 90 MeV sulfur beam by a magnetic spectrograph behind the target chamber in transmission geometry, an overall relative energy width of 3.8×10−5 fwhm was demonstrated.

Enhanced tunability of magnetron sputtered Ba0.5Sr0.5TiO3 thin films on c-plane sapphire substrates

Thin films of Ba0.5Sr0.5TiO3 (BST) were deposited on c-plane (0001) sapphire by rf magnetron sputtering and investigated by complementary materials analysis methods. Microwave properties of the films, including tunability and Q factor were measured from 1to20GHz by patterning interdigital capacitors (IDCs) on the film surface. The tunability is correlated with texture, strain, and grain size in the deposited films. An enhanced capacitance tunability of 56% at a bias field of 200kV∕cm and total device Q of more than 15 (up to 20GHz) were achieved following postdeposition annealing at 900°C.

Sensitive 3D hydrogen microscopy by proton proton scattering

Elastic proton proton scattering is a sensitive and fast method for hydrogen analysis. Utilising a nuclear microprobe it is actually the only technique for the absolute quantification of hydrogen distributions with micrometer or even better lateral resolution. High proton energies, e.g. 20 MeV, allow a wide field of applications since even materials, some 100 μm thick, can be analysed. Irradiation damage is reduced to a minimum compared to all other known ion beam analysis techniques, because a large solid angle of detection of some stradian can be used and the nuclear scattering cross section for protons at these energies is enhanced nearly three orders of magnitudes compared to Coulomb scattering. As a consequence, a sensitivity in the ppm range for hydrogen microscopy is possible. However, the large solid angle of detection induces geometrical effects in the energy analysis which are kept within a physical limit by an angular resolution of 10 mrad e.g. by utilising an annular silicon strip detector of 2.3 sr solid angle of detection. Therefore, the third dimension is provided with a depth resolution better 10 μm using the energy information of the scattered protons.

Water in natural olivine—determined by proton-proton scattering analysis

Abstract Here we present water concentration data for olivine from different host rocks, measured with a nuclear technique using proton-proton scattering. This method, which is used here for the first time on olivine, is very powerful for determining trace amounts of water. The studied olivine specimens differ in their H2O contents, ranging from 4 to 51 wt ppm (=10-117 atom ppm H). The lowest concentrations are found in olivine from spinel peridotite xenoliths, the highest concentrations in olivine from alpine-type peridotite; the contents of an ophiolitic and a hydrothermal olivine are intermediate. Infrared spectroscopy was applied to ensure that the measured water contents stem solely from hydroxyl defects in the mineral structure. The infrared spectra differ from sample to sample. Five of six olivine specimens show absorption bands typical of hydroxyl groups associated with Ti defects. These olivines differ in their Ti contents by two orders of magnitude. However, a correlation of water and Ti content was not observed.

The Munich ion microprobe: Characteristics and prospect

Abstract The newly developed ion microprobe SNAKE (superconducting nanoscope for applied nuclear (Kern-) physics experiments) has gone into routine operation at the Munich 14 MV tandem accelerator. It focuses ion beams, from protons to uranium, with energies that are about 10 times larger than they are available at standard nuclear microprobes. Lateral resolutions of Δ x =1.6 μm and Δ y =1.2 μm for x - and y -direction at full aperture and as low as Δ x =600 nm and Δ y =150 nm for a pencil beam have been achieved so far. The latter values are limited by positional drifts and 50 Hz oscillating fields which have become obvious in time resolved measurements. SNAKE opens new possibilities for analysis of microstructured materials as well as materials modifications. The highlights are three dimensional hydrogen analysis using proton proton scattering, high resolution transmission energy loss measurements utilizing a magnetic spectrograph and materials modification with available high energy proton and heavy ion beams. Standard techniques like particle induced X-ray emission, elastic and inelastic scattering are also used for imaging. The paper summarizes some of the prospects using the enlarged range of available ion beams and ion energies.