Absorption and birefringence study for reduced optical losses in diamond with high NV concentration

The use of diamond color centers such as the nitrogen-vacancy (NV) center is increasingly enabling quantum sensing and computing applications. Novel concepts like cavity coupling and readout, laser threshold magnetometry and multi-pass geometries allow significantly improved sensitivity and performance via increased signals and strong light fields. Enabling material properties for these techniques and their further improvements are low optical material losses via optical absorption of signal light and low birefringence. Here we study systematically the behavior of absorption around 700 nm and birefringence with increasing nitrogen- and NV-doping, as well as their behavior during NV creation via diamond growth, electron beam irradiation and annealing treatments. Absorption correlates with increased nitrogen-doping yet substitutional nitrogen does not seem to be the direct absorber. Birefringence reduces with increasing nitrogen doping. We identify multiple crystal defect concentrations via absorption spectroscopy and their changes during the material processing steps and thus identify potential causes of absorption and birefringence as well as strategies to fabricate CVD diamonds with high NV density yet low absorption and low birefringence.Comment: Accepted by Philosophical Transactions A (DOI: 10.1098/rsta.2022.0314

Structure determination of neutral mgo clusters-hexagonal nanotubes and cages

Contains fulltext : 99093.pdf (publisher's version ) (Open Access

Infrared spectroscopy and binding geometries of oxygen atoms bound to cationic tantalum clusters

Contains fulltext : 99086.pdf (publisher's version ) (Open Access

Vibrational spectroscopy of neutral silicon clusters via far-ir-vuv two color ionization

Contains fulltext : 99127.pdf (publisher's version ) (Open Access

Communication: IR spectroscopy of neutral transition metal clusters through thermionic emission

Contains fulltext : 117356.pdf (publisher's version ) (Open Access

Structure determination of neutral MgO clusters-hexagonal nanotubes and cages

Structural information for neutral magnesium oxide clusters has been obtained by a comparison of their experimental vibrational spectra with predictions from theory. (MgO)n clusters with n = 3-16 have been studied in the gas phase with a tunable IR-UV two-color ionization scheme and size-selective infrared spectra have been measured. These IR spectra are compared to the calculated spectra of the global minimum structures predicted by a hybrid ab initio genetic algorithm. The comparison shows clear evidence that clusters of the composition (MgO)3k (k = 1-5) form hexagonal tubes{,} which confirm previous theoretical predictions. For the intermediate sizes (n [not equal] 3k) cage-like structures containing hexagonal (MgO)3 rings are identified. Except for the cubic (MgO)4 no evidence for bulk like structures is found

Communication: IR spectroscopy of neutral transition metal clusters through thermionic emission

The resonant multiple photon excitation of neutral niobium clusters using tunable infrared (IR) radiation leads to thermionic emission. By measuring the mass-resolved ionization yield as a function of IR wavenumber species selective IR spectra are obtained for Nb-n (n = 5-20) over the 200-350 cm(-1) spectral range. The IR resonance-enhanced multiple photon ionization spectra obtained this way are in good agreement with those measured using IR photodissociation of neutral Nb-n-Ar clusters. An investigation of the factors determining the applicability of this technique identifies the internal energy threshold towards thermionic emission in combination with a minimum required photon flux that rapidly grows as a function of excitation wavelength. (C) 2013 AIP Publishing LLC