We employ high-resolution total neutron scattering in conjunction with reverse Monte Carlo simulations to examine, in a detailed and unbiased manner, the crystal structure of the vacancy-ordered oxide pyrochlore Pb 2 Ru 2 O 6 O 0.5 in light of its structural analogy with proton ordering in the structures of ice. We find that the vacancy and the O ion are completely ordered, and that the average structure in the F43m space group describes the vacancy ordering precisely. We complement these results with an examination of the Pb 2+ lone pair network using density functional electronic structure calculations, and a comparison of the low-temperature lattice-only heat capacity of Pb 2 Ru 2 O 6 O 0.5 with that of other related pyrochlores.

The wide applicability of atmospheric pressure plasma jets in biomedicine stems from the presence of reactive nitrogen and oxygen species generated in these plasma jets. Knowing the absolute concentration of these reactive species is of utmost importance as it is critical, along with the particle flux obtained from the plasma feed gas flow rate to ensure that the correct dosage is applied during applications. In this study, we investigate and report the ground state OH(X) number density acquired using cavity ringdown spectroscopy, along the propagation axis (z-axis) of a cold atmospheric pressure helium plasma plume. The jet was generated by a repetitively pulsed mono-polar square wave of duration 1 μs running at a frequency of 9.9 kHz. The voltage supplied was 6.5 kV with the helium flow rate fixed at 3.6 standard liters per minute. The rotational and vibrational temperatures are simulated from the second positive system of nitrogen,  N2(C3πu−B3πg), with the rotational temperature being spatially constant at 300 K along the propagation axis of the atmospheric pressure plasma jet while the vibrational temperature is 3620 K at the beginning of the plume and is observed to decrease downstream. The OH(A) emission intensity obtained via optical emission spectroscopy was observed to decrease downstream of the plasma jet. The OH(X) number density along the propagation axis was initially 2.2 × 1013 molecules cm−3 before increasing to a peak value of 2.4 × 1013 molecules cm−3, from which the number density was observed to decrease to 2.2 × 1013 molecules cm−3 downstream of the plasma jet. The total OH(A, X) in the plasma jet remained relatively constant along the propagation axis of the plasma jet before falling off at the tip of the jet. The increase in vibrational temperature downstream and the simultaneous measurements of both the excited state OH(A) and the ground state OH(X) reported in this study provide insights into the formation and consumption of this reactive oxygen species while also providing a reference for determining the radical number density dosage for future cold plasma irradiation studies.

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Articles you may be interested inEffect of plasma polymerization film on reducing damage of reactive ion etched silicon substrates with CHF3+O2 plasmas J. Vac. Sci. Technol. B 15, 66 (1997); 10.1116/1.589257 Sidewall and surface induced damage comparison between reactive ion etching and inductive plasma etching of InP using a CH4/H2/O2 gas mixture Reactive ionetchinginduced damage in silicon using SF6 gas mixtures In this work, reaction ion etching ͑RIE͒ induced damage and its impact on device performance have been characterized and evaluated using a variety of characterization techniques for two technologically important gas mixtures: CHF 3 /O 2 for selective oxide etching, and SF 6 /O 2 for selective poly Si or crystalline Si etching. Current-voltage characteristics of Al/Si Schottky diodes fabricated on the RIE exposed Si surface reveal significant barrier height shifts for the CHF 3 /O 2 process while showing little change for the SF 6 /O 2 processes. Carrier generation lifetime is degraded by at least one order of magnitude, with the degradation due to CHF 3 /O 2 processes being more severe. Scanning electron microscopy and Auger electron spectroscopy support the idea that the defects that give rise to the altered electrical behavior are most likely Si lattice damage instead of metal contamination and/or morphologic modification. Rapid thermal annealing of the CHF 3 /O 2 etched samples has a negative effect on I -V recovery precluding simple application of RTA for removing RIE damage. In the RIE exposed oxide, the two distinctively different gas mixtures induce very similar C -V and Si/SiO 2 interface property changes, suggesting that the high energy photons present in the plasma glow are the most probable source of damage in the oxide.

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