Direct Detection of Vacuum Ultraviolet Radiation through an Optical Sampling Orifice: Spatially Resolved Emission Studies of Argon Resonance Lines from an Inductively Coupled Plasma

Abstract

Optical spectra are observed through a sampling orifice inserted directly into an inductively coupled plasma. The optical system does not use lenses, mirrors, or windows so that vacuum ultraviolet wavelengths as low as the ionization energy of Ar (78.7 nm) can be detected. These lines are readily observed with lateral spatial resolution. The intensity of Ar I 106.67 nm is studied for various plasma operating parameters and observation positions. The number density for the upper state for this line (3P1) is estimated to be of the order of 1011 cm−3 in the axial channel, which is similar in magnitude to the populations of the nearby metastable Ar levels measured previously. The Ar I line at 104.82 nm is self-reversed, indicating that Ar resonant radiation can definitely be trapped in the inductively coupled plasma. The results support the radiation trapping hypothesis but do not quantitatively determine the magnitude of energy transfer from the induction region to the axial channel by this mechanism.

Inductively Coupled Plasma Mass Spectrometry A Review

“…Argon has strong resonance lines in this wavelength region, i.e., Ar I 104.82 and Ar I 106.67 nm. 8 Olivares and Houk6, however, constructed an instrument with no baffle plate using an off-axis detector. Although they obtained a high ion transmission efficiency, the background was relatively high (1000 -10000 -1) compared to commercial instruments (1-20 9 or 30-100 s-11o).…”

Elemental analysis of landfill gas by ICP emission spectrometry—new approach for monitoring organochlorine compounds

“…ICP emission spectrometry has been used extensively for the determination of metallic constituents in environmental samples, but only a limited amount of the literature relates to the determination of halogens due to the location of prominent lines in the vacuum ultraviolet. In this context an important instrumental development was reported by Houk et al 2,3 These workers used a water-cooled Cu cone, which was inserted into the ICP to permit direct viewing of source radiation. The approach was subsequently utilised for sensitive determinations of Cl, Br, C and S in simple argon gas mixtures (99 ppm SF 6 , 99 ppm CF 2 Cl 2 , 98 ppm CF 3 Br) using a purposebuilt direct injection probe linked to a gas sampling manifold with a ¯ow injection valve (sample loops 15±500 ml).…”

Direct detection of vacuum ultraviolet radiation through an optical sampling orifice: determination of nonmetals in gaseous samples by inductively coupled plasma atomic emission spectroscopy

“…Observation of these resonance lines with conventional instrumentation is complicated by absorption of radiation by oxygen in the atmosphere and by the mirrors and/or windows employed in the optical transfer system. Previous studies have shown that vacuum UV radiation can be readily sampled and detected via an orifice in a metal cone inserted directly into the ICP (1,2). In this paper we describe the determination of several nonmetals in gases by this optical sampling technique.…”

“…Also, the outer tube was extended to 32 mm from the top of the inner tube to prevent air entrainment. The basic construction principles of the DIP were derived from the direct injection nebulizer (DIN) 1 Present address: Dow Chemical Co., Midland MI 48640. 0003-2700/88/0360-0023801.50/0 for liquids (4)(5)(6).…”