57 research outputs found
Identification of Slow States at the SiO2/SiC Interface through Sub-Bandgap Illumination
We show that it is possible to obtain information relating to deep level interface traps, or so called ‘slow states’, by using the photo-CV characterisation method. Sub-bandgap illumination has been chosen in order to avoid band-to-band excitation for the creation of minority carriers. This enables information to be extracted from trapping states at the SiO2/SiC interface that are energetically deep within the band gap. Empirical observations of deep level trapping states with life times in the order of tens of hours are reported and the interface trap density as a function of energy has been extracted using the Terman method. Characterisation of these interface states will aid the development of new fabrication processes, with the aim of reducing the interface trap density to the same level as that of the SiO2/Si interface and facilitating the production of higher quality SiC based devices
Enhanced ozone loss by active inorganic bromine chemistry in the tropical troposphere
Abstract Bromine chemistry, particularly in the tropics, has been suggested to play an important role in tropospheric ozone loss (Theys et al., 2011) although a lack of measurements of active bromine species impedes a quantitative understanding of its impacts. Recent modelling and measurements of bromine monoxide (BrO) by Wang et al. (2015) have shown current models under predict BrO concentrations over the Pacific Ocean and allude to a missing source of BrO. Here, we present the first simultaneous aircraft measurements of atmospheric bromine monoxide, BrO (a radical that along with atomic Br catalytically destroys ozone) and the inorganic Br precursor compounds HOBr, BrCl and Br2 over the Western Pacific Ocean from 0.5 to 7 km. The presence of 0.17-€“1.64 pptv BrO and 3.6-8 pptv total inorganic Br from these four species throughout the troposphere causes 10-20% of total ozone loss, and confirms the importance of bromine chemistry in the tropical troposphere; contributing to a 6 ppb decrease in ozone levels due to halogen chemistry. Observations are compared with a global chemical transport model and find that the observed high levels of BrO, BrCl and HOBr can be reconciled by active multiphase oxidation of halide (Br- and Cl-ˆ’) by HOBr and ozone in cloud droplets and aerosols. Measurements indicate that 99% of the instantaneous free Br in the troposphere up to 8 km originates from inorganic halogen photolysis rather than from photolysis of organobromine species
A kinetic study of the reactions of IO with CH<sub>3</sub>O<sub>2</sub> and CF<sub>3</sub>O<sub>2</sub>
The bioanalysis of urinary modified nucleosides by mass spectrometry: their study as potential metabolomic biomarkers of cancer development
Efficiency of formation of CH<sub>3</sub>O in the reaction of CH<sub>3</sub>O<sub>2</sub> with ClO.
Investigation into the kinetics and mechanism of the reaction of NO3 with CH3O2 at 298 K and 2.5 Torr
Kinetics and mechanism of the reaction of CH<sub>3</sub> and CH<sub>3</sub>O with ClO and OClO at 298 K.
Rate constants for the reactions of C2H5, C2H5O and C2H5O2 radicals with NO3 at 298 K and 2.2 Torr.
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