Luminescence of Oxygen Atoms Stimulated by Metastable Helium at Cryogenic Temperatures

Abstract

We present investigations of the afterglow of oxygen-helium gas mixtures at cryogenic temperatures. The cooling of a helium jet containing trace amounts of oxygen after passing through a radio frequency discharge zone led to the observation of strong emissions from atomic oxygen. The effect results from the increasing efficiency of energy transfer from metastable helium atoms and molecules to oxygen impurities in the cold dense helium vapor. This effect might find an application for the detection of small quantities of the impurities in helium gas.

Effects of discharge voltage waveform on the discharge characteristics in a helium atmospheric plasma jet

“…For this purpose, we performed detailed optical emission spectroscopy observations of the O atoms. [23][24][25][26][27][28][29][30][31][32] The optical emission from the O atom is useful for rough estimation of the existence of reactive O species in the transient plasma jet, because most reactive O species are produced via the channel that is associated with O optical emission. 22 Our optical emission measurements clearly demonstrate the marked effects of the voltage waveform on the plasma jet characteristics: application of a voltage with a fast rise time induces rapid growth of the pulse discharge and results in the production of large amounts of reactive O species.…”

Optical and Electron Spin Resonance Studies of Xenon–Nitrogen–Helium Condensates Containing Nitrogen and Oxygen Atoms

“…The setup at Texas A&M University is described in more detail elsewhere. 22 The light emission from the sample passed through optical slits in both the helium and the nitrogen glass dewars and was collected by a lens into an optical fiber which splits into two separate channels, one of which was attached to an Ocean Optics spectrometer and the other to an Andor Shamrock SR500 spectrograph. The spectrometer allows spectrum capture rates up to 1000 full spectra/s (within the spectral range of 200−1100 nm).…”

“…Optical experiments have been carried out with two experimental setups possessing very similar cryogenic components, each including glass dewars for liquid nitrogen and helium, an atom source, a glass beaker for sample collection, and a fountain pump for maintaining the HeII supply in the beaker. The setup at Texas A&M University is described in more detail elsewhere . The light emission from the sample passed through optical slits in both the helium and the nitrogen glass dewars and was collected by a lens into an optical fiber which splits into two separate channels, one of which was attached to an Ocean Optics spectrometer and the other to an Andor Shamrock SR500 spectrograph.…”

Excimers in the Lowest Rotational Quantum State in Liquid Helium

“…The establishment of the spectral fingerprint of solvated helium excimers in liquid helium and the associated pressure- and temperature-dependent lineshift is encouraging for use of molecular probes in the investigation of superfluid helium, for which a number of techniques for the injection of molecules are currently being pursued. − In a broader context, such experiments may lead to a better understanding of molecular solvation in related systems − in particular and fluids in general.…”

“…[40][41][42][43] In a broader context, such experiments may lead to a better understanding of molecular solvation in related systems [44][45][46] in particular, and fluids in general.…”