Search results for "Nitrogen"
showing 10 items of 1200 documents
Gain stabilization and noise minimization for SiPMs at cryogenic temperatures
2018
Abstract The performance of solid-state photon detectors such as avalanche photodiodes or silicon photomultipliers (SiPMs) is strongly affected by temperature. Important device characteristics for the detection of low light levels or single photons are photon detection efficiency, dark noise, and gain. In the present work the C-series SiPMs from SensL was characterized in cryogenic environments. At 77 K the SiPMs proved to be an excellent choice for single photon detection and an operation point with minimum noise contributions was found. At 4 K the performance was degraded, exhibiting a smaller gain and a larger noise.
Investigation of nitrogen-related acceptor centers in indium selenide by means of photoluminescence: Determination of the hole effective mass
1997
In this work we report on steady-state and time-resolved photoluminescence (PL) measurements in nitrogen-doped p-type indium selenide in the 33--210-K temperature range. In samples with low nitrogen concentration the photoluminescence spectrum consists of exciton-related peaks and a band-to-acceptor recombination peak (2.1-\ensuremath{\mu}s lifetime) with LO-phonon replica. An ionization energy of 65.5 meV is proposed for the nitrogen-related acceptor. A long-lived (18 \ensuremath{\mu}s) component, which consists of an asymmetric broadband centered around the acceptor peak, has been also detected by means of time-resolved PL. Samples with a higher nitrogen concentration show a PL spectrum t…
Photoluminescence at the ground-state level anticrossing of the nitrogen-vacancy center in diamond: A comprehensive study
2021
Physical review / B 103(3), 035307 (2021). doi:10.1103/PhysRevB.103.035307
Silicon photomultiplier properties at cryogenic temperatures
2015
Abstract The properties of different types of silicon photomultipliers (SiPMs) were studied at cryogenic temperatures. In liquid nitrogen at 77 K, problems with quenching in Hamamatsu SiPMs and with the protective epoxy layer, covering Zecotek SiPMs, were observed. Tests with one Zecotek SiPM were successful after removal of the epoxy layer. In liquid helium at 4 K, fast signals with pulse lengths shorter than 50 ns were observed, the dark count rate was below 10 Hz and no after-pulses were detected. The gain, as a function of over-voltage, was comparable to room temperature. The SiPM׳s response to photons was found to be linear with intensity for low light levels and single-photon detectio…
Dynamical stabilization of spin systems in time-dependent magnetic fields
2011
The quantum dynamics of a spin system subjected to a Rabi magnetic field configuration modified by a weak oscillating field along the Z-axis is investigated. We show that when the Rabi frequency is appropriately matched with the frequency of the perturbative field, the spin system exhibits a dynamical stabilization phenomenon defined as the tendency to occupy a fixed quantum superposition during a finite period of time.
J-File Sum Rule Tests for the 3s-3p Transition Array in Singly Ionized Nitrogen - Comparison of Measured and Calculated Data
2005
1. IntroductionIn recent years quite a large number of transition probabilities of spectrallines of light elements have been determined including data for singly ionizednitrogen [1{7]. Some of these experimental as well as theoretical studies providealso data for a few triplet{singlet intersystem transitions, being very interestinge.g. from astrophysical point of view. The energy level system of NII has adistinguished feature compared to the neighboring two members of the carbonisoelectronic sequence (CI, OIII) | the energy difierence between the excitedterms 3
Dynamic N14 nuclear spin polarization in nitrogen-vacancy centers in diamond
2020
We studied the dynamic nuclear spin polarization of nitrogen in negatively charged nitrogen-vacancy (NV) centers in diamond both experimentally and theoretically over a wide range of magnetic fields from 0--1100 G covering both the excited-state level anticrossing and the ground-state level anticrossing magnetic field regions. Special attention was paid to the less studied ground-state level anticrossing region. The nuclear spin polarization was inferred from measurements of the optically detected magnetic resonance signal. These measurements show that a very large (up to $96\ifmmode\pm\else\textpm\fi{}2%$) nuclear spin polarization of nitrogen can be achieved over a very broad range of mag…
Association of Exposure to Ambient Air Pollution With Thyroid Function During Pregnancy
2019
Key Points Question Is exposure to ambient air pollution in the first trimester associated with thyroid function throughout pregnancy? Findings Among 9931 pregnant women in 4 European cohorts and 1 US cohort, an increase of 5 μg/m3 in exposure to particulate matter with an aerodynamic diameter of 2.5 μm or less was associated with 20% higher odds of hypothyroxinemia. Meaning The findings of this study raise the possibility that exposure to particulate matter might disrupt thyroid function in pregnant women.
What is the function of neuroglobin?
2009
SUMMARY For a long time, haemoglobin and myoglobin had been assumed to represent the only globin types of vertebrates. In 2000, however, we discovered a third globin type by mining the genome sequence data. Based on a preferential expression in the nervous system, this globin is referred to as neuroglobin. Despite nine years of research, its function is still uncertain and a number of hypotheses have been put forward. Neuroglobin enhances cell viability under hypoxia and under various types of oxidative stress in transgenic systems, but does not appear to be strongly upregulated in response to stress. A close phylogenetic relationship with invertebrate nerve globins and its positive correla…
Screening of microalgae and LED grow light spectra for effective removal of dissolved nutrients from cold-water recirculating aquaculture system (RAS…
2019
Popularity of recirculating aquaculture systems (RAS) is increasing. Because of the high water recirculation rate, dissolved nutrients originating from fish feed are concentrated enough in RAS wastewater (WW) to enable growth of primary producers, e.g. microalgae. This study evaluated nitrate-nitrogen (NO3-N) and phosphate-phosphorus (PO4-P) removal efficiency of ten temperate zone freshwater microalgae species during their exponential growth phase in unfiltered RAS WW at 17 ± 0.5 °C. Growth and nutrient uptake efficiency of six green and four non-green microalgae strains were compared between WW and reference growth medium in batch monocultures. The effect of three different LED grow light…