Jules Z. Klose

Lifetimes of Some 4p Levels in Argon I

Mean lives of four electronically excited atomic levels in Ar i have been determined using a method of delayed coincidence. The measured values of the mean lives of the 2p1 through 2p4 (Paschen notation) levels in neutral argon determined from transitions with associated wavelengths extending from 6677 to 7147 A are as follows: 2p1, 21±2 nsec; 2p2, 25±1 nsec; 2p3, 26±1 nsec, and 2p4, 31±2 nsec. The lifetimes were estimated to contain systematic errors varying from 5% to 15% and are presented in comparison with results of other workers.

Experimental Lifetimes of the 5p Levels in Argon i

Mean lives of 7 of the 10 5p atomic levels in Ar i have been determined using electronic excitation and a method of delayed coincidence. The measured values, in nanoseconds, of the mean lives of the 3p1 and 3p5 through 3p10 levels (Paschen notation) in neutral argon are: 3p1, 71±2; 3p5, 95±2; 3p6, 124±3; 3p7, 149±3; 3p8, 166±5; 3p9, 141±2; and 3p10, 189±3. The error given with each lifetime is the standard deviation in the mean as evaluated from the dispersion of the individual measurements. Wavelengths used in the determinations ranged from 4159 to 4702 A. The lifetimes were estimated to contain systematic errors varying from 5% to 15% and are presented in comparison with values obtained by combining theoretical calculations with other experimental results.

Vacuum-ultraviolet spectral-irradiance calibrations: method and applications

A method to determine the spectral irradiance of a radiation source in the vacuum ultraviolet through the use of recently developed spectral-radiance standards is described. The method has been applied between 138 and 310 nm, and the spectral irradiances of several different light sources have been measured on an absolute scale with estimated uncertainties less than 10%.

Characterization of a Pt-Ne hollow cathode spectral line source

A source which produces a rather uniform distribution of spectral lines over the wavelength range from 115 to ~350 nm is being investigated as a secondary radiometric standard for use in space. This source is a sealed lamp with a hollow cathode of platinum and a fill gas of neon. A version of this lamp has already been flown in space but only as a wavelength standard. The following properties were studied: warmup time, stability, emission as a function of current, repeatability, spatial characteristics, impurities, angular dependence, long term behavior, and radiance.

Monochromatic source of Lyman-α radiation

A source has been developed which produces a pure spectrum of Lyman-α radiation (1215.7 A). This source incorporates a wavelength selective filter and an rf-excited helium-filled lamp containing a mixture of uranium and uranium hydride in a sidearm. The uranium serves as a getter to eliminate atmospheric contaminants, and the uranium hydride, when heated, supplies H2 in a reproducible manner. The filter consists of a flowing-oxygen cell and a narrowband interference filter. The distinctive advantage of this device is that radiation in the VUV at a well-defined wavelength is obtained without the use of a monochromator. Characteristics of the source and measurements of the irradiance of the spectral line are given for a typical lamp. The irradiance and spectral purity are seen to be not strongly dependent on oxygen flow.

Measurement Of Atomic Uranium Lifetimes For Isotope Separation

Following a brief discussion of uranium isotope separation using lasers, the delayed coincidence method of measuring atomic mean lives with pulsed electron beams utilized here is described along with the beam source used to supply the free uranium atoms for measurement. Experimental details involved in the lifetime measurement are next discussed followed by the effect of resonance radiation imprisonment on the measured lifetimes. Finally, lifetime measurements involving the 3584.9 Å and 5915.4 Å transitions in natural uranium are described, and the previously reported result of 7.3 ± 1.1 ns ior the mean life of the upper level of the 3584.9 Å transition (27886.99 cm -1 ) is presented.