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The loss rate O2(a 1Δg) on a variety of surfaces has been investigated. At 300 K, the most rapid deactivants are Cu, Ag, and Co, with Fe, Ni, Pt, and Pd being somewhat less active. Numerous metals exhibit very low activity, including Al, Au, and W. Quite different temperature dependences were observed among the metals, with the activity of Ag decreasing markedly with increasing temperature over the range 220–470 K, that of Ni increasing, and that of Pd showing little change. The loss-rate–temperature profiles of Fe, Co, and Ni are similar, paralleling the behavior observed in a separate study on these three metals for higher-lying electronically excited states O2. [ABSTRACT FROM AUTHOR]

In an attempt to isolate the important parameters governing the production of the 4–5 eV states of O2 generated from O-atom recombination on metallic surfaces, we have investigated the effects of substrate composition and temperature on the intensity of the UV glows that are generated. Of the 22 metals investigated, glow-producing activity is localized in the VIIIb group on the Periodic Table, led by Ni and including Pt, Co, Pd, Fe, and also Au. One parameter that appears to be directly or indirectly linked to this effect is the electronic heat capacity. The six active metals exhibit unique temperature signatures, with Fe, Ni, and Co being distinctly different from Pd, Pt, and Au, measured over the 220–470 K range. The spectra of the UV glows, consisting of the A–X, A’–a, and c–X transitions of O2, differ only in intensity between the metals, not in state or vibrational level distributions. This suggests that the observed spectra are mediated by gas-phase interactions. The data indicate that at high temperatures, surface quenching of the A, A’, and c states is rapid, and that under low-pressure conditions, this effect can be observed even for excited molecules generated in the gas phase. Studies with nickel alloys indicate that the percentage of Ni in a sample is the overriding determinant of the glow intensity, regardless of the other components. Although existing data on energy accommodation coefficients lead to the conclusion that most of the energy in O2 molecules leaving surfaces should be in vibrational modes of the ground state, we have not been able to substantiate this idea. [ABSTRACT FROM AUTHOR]

The 532 nm multiphoton dissociation of NO2 has been investigated, following the work of Matsumi et al. [Laser Chem. 1, 113 (1983)], which demonstrated that highly vibrationally excited O2 (v≤25) is a product. We have shown that O2(v) is generated in a secondary reaction, possibly through the interaction between primary O(1S) and the parent molecule. Competitive quenching experiments with N2 indicate that O(1D) is not involved in O2(v=24) production. Primary NO(v) has been detected by one- and two-photon excitation, with v≤7. Its source is probably 532 nm two-photon dissociation of NO2. The generation of O(1S) requires absorption of four 532 nm photons by NO2. [ABSTRACT FROM AUTHOR]

Presents a study that described plasma properties of a hydrocarbon arcjet used in the plasma deposition of diamond thin films. Information on how the ject operated; Optical emission spectra; Langmuir probe diagnosis of the plasma.