Richard A. Keller and Edward F. Zalewski, "Noise considerations, signal magnitudes, and detection limits in a hollow cathode discharge by optogalvanic spectroscopy," Appl. Opt. 19, 3301-3305 (1980)
It is demonstrated that the noise in a hollow cathode discharge results mainly from statistical fluctuations of the electrons in the circuit. For the elements Na, U, Eu, and Zr, approximately one extra electron is produced for every one thousand photons absorbed. The nondependence of the magnitude of the optogalvanic signal on the ionization potential of the irradiated atom leads us to postulate a mechanism where the principal effect of laser irradiation is to pump energy into the electron gas.
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With the exception of one Zr tube, the fill gas was neon (~5 Torr); the ballast resistor was 26.9 kΩ.
The laser was not single frequency, but its output consisted of three modes with an intermode separation ~1.5 GHz. Only the center mode, which contained about one-half of the intensity, overlapped the absorption band.
Single pass absorption.
The sign of ΔV depends upon whether ΔV is measured across the tube or the ballast resistor. The sign given here is for measurement across the ballast resistor.
When error bars are given, two or three measurements were made. These values were reproducible from day to day.
Different discharge tube.
Ar fill gas (~5 Torr).
Table II
Ratio of the Laser-Induced Voltage Change to the Laser Power Absorbed in Neon as a Function of Discharge Currenta
Uranium metal cathode. Neon pressure is ~5 Torr. Ballast resistor is 26.9 kΩ except as noted. λ = 6143.1 Å. Transition is 3P2 → 2P6.
Single pass absorption.
The sign of ΔV depends upon whether ΔV is measured across the tube or the ballast resistor. The sign given here is for measurement across the ballast resistor.
Ballast resistance increased to 450 kΩ.
Table III
Signal to Noise Calculated for a −0.1-Ω Change in the Tube Impedancea
Current is ~25 mA.
E. F. Zalewski, R. A. Keller, and R. Engleman, Jr., J. Chem. Phys. 70, 1015 (1979).
R. A. Keller, R. Engleman, Jr., and E. F. Zalewski, J. Opt. Soc. Am. 69, 738 (1979).
B. E. Warner, “Investigation of the Hollow Cathode Discharge at High Current Density,” Ph.D. Thesis, Physics Department, U. Colorado (1979).
Tables (6)
Table I
Ratio of the Laser-Induced Voltage Change to the Laser Power Absorbed: U, Na, Eu, and Zr a
With the exception of one Zr tube, the fill gas was neon (~5 Torr); the ballast resistor was 26.9 kΩ.
The laser was not single frequency, but its output consisted of three modes with an intermode separation ~1.5 GHz. Only the center mode, which contained about one-half of the intensity, overlapped the absorption band.
Single pass absorption.
The sign of ΔV depends upon whether ΔV is measured across the tube or the ballast resistor. The sign given here is for measurement across the ballast resistor.
When error bars are given, two or three measurements were made. These values were reproducible from day to day.
Different discharge tube.
Ar fill gas (~5 Torr).
Table II
Ratio of the Laser-Induced Voltage Change to the Laser Power Absorbed in Neon as a Function of Discharge Currenta
Uranium metal cathode. Neon pressure is ~5 Torr. Ballast resistor is 26.9 kΩ except as noted. λ = 6143.1 Å. Transition is 3P2 → 2P6.
Single pass absorption.
The sign of ΔV depends upon whether ΔV is measured across the tube or the ballast resistor. The sign given here is for measurement across the ballast resistor.
Ballast resistance increased to 450 kΩ.
Table III
Signal to Noise Calculated for a −0.1-Ω Change in the Tube Impedancea
Current is ~25 mA.
E. F. Zalewski, R. A. Keller, and R. Engleman, Jr., J. Chem. Phys. 70, 1015 (1979).
R. A. Keller, R. Engleman, Jr., and E. F. Zalewski, J. Opt. Soc. Am. 69, 738 (1979).
B. E. Warner, “Investigation of the Hollow Cathode Discharge at High Current Density,” Ph.D. Thesis, Physics Department, U. Colorado (1979).