Optical Emission from Argon Excited by Alpha Particles: Quenching Studies

Abstract

Optical emission from argon gas excited with alpha particles has been studied to determine if electronic states of long lifetimes are excited by swiftly moving charged particles as has been observed in studies of ionization. The spectrum from argon showed a continuum which could be separated into three distinct bands with maxima at 1300, 1800, and 2000 Å. The light intensity of the 2200-Å band was readily quenched with the addition of about 2% of CH4, CO2, O2, and Kr. The 1800-Å band was quenched more slowly than the 2200-Å band by the impurity gases. The results support the notion that alpha-particle excitation of argon at high pressures leaves the argon in long-lived states of about 11.5 or 14.5 eV. The observed continua appear to arise mainly from Franck—Condon transitions between two excited states and the ground repulsive state of the argon dimer which forms as a consequence of the long lifetimes of the excited atoms.

Ozone Generation from Argon-Oxygen Mixtures in Presence of Different Packing Materials within Dielectric Barrier Discharge Gap

“…However, TiO 2 is also known to contribute in surface photo-catalysis via the intermediacy of e − and hole + along with excited species (-Ti 3+ -O − ) * in the presence of UV light, as made available from in situ emission from Ar * in reaction (2) and O 2 * formed in reaction [4] (Fujishima et al 2000;Hoffmann et al 1995;Strickler and Arakawa 1964). Typical Lissajous plots at 50 Hz and kHz ACF respectively for experiments 31 and 35 are presented in Figure 11.…”

Underground neutrino detectors for particle and astroparticle Science: The Giant Liquid Argon Charge Imaging ExpeRiment (GLACIER)

“…Ionizing radiation in liquid noble gases leads to the formation of excimers in either singlet or triplet states [99,100], which decay radiatively to the dissociative ground state with characteristic fast and slow lifetimes (τ f ast ≈ 6 ns, τ slow ≈ 1.6µs in liquid argon with the so-called second continua emission spectrum peaked at 128 ± 10 nm [101]). Scintillation light readout provides information on events occurring in the detector.…”

Fluorescence des gaz rares à haute pression excités par flash X rapide

“…Les transitions à l'origine des seconds continus sont parfaitement identifiés depuis fort longtemps [10]. Ils correspondent à la désexcitation radiative des deux états moléculaires excités les plus bas en énergie de la molécule neutre Rg2-Par contre, la discussion reste très ouverte sur l'identification du ou des états moléculaires à l'origine des troisièmes continus des gaz rares [7][8][9][11][12][13][14] observés pour la première fois il y a trente ans. Il est cependant aujourd'hui acquis que ces continus sont d'origine ionique.…”