Scintrex Limited

John C Robbins

John D Kinrade

Harold O Seigel

We have discovered that certain photoluminescent minerals of zinc, fluorine, tungsten, molybdenum, mercury and other elements which may naturally occur at the surface of the earth can be selectively detected in the presence of most other photoluminescent minerals and organic materials which are likely to occur at the earth's surface. The basis of selective detection is the discovery that the lifetimes of photoluminescent emission of materials in the latter class are much shorter than the lifetimes of photoluminescent emission of materials in the former class. This invention utilizes this discovery in the detection of minerals of uranium, zinc, lead, fluorine, tungsten, molybdenum, mercury and other elements. In one embodiment of the invention, using a laser or other short duration source of optical excitation, measurements of the photoluminescent response of the earth are made at times sufficiently long for the photoluminescence of other common and unwanted sources to have substantially decayed, thereby selectively detecting and identifying certain minerals of potential economic interest. In another embodiment a source of light is modulated at a predetermined frequency and the photoluminescent response of the earth which is out-of-phase with the source is measured. In a third embodiment this source of light may be incident solar radiation after passage through a suitable modulator.

Detection of certain minerals of zinc, tungsten, fluorine, molybdenum,

This invention is a method that uses the previously undiscovered fact that the phosphorescent lifetime of the uranyl ion at very dilute concentrations in an aqueous solution is anomalously long in comparison to that of other commonly-occurring phosphorescent species, wherein the uranyl ions in the low concentration sample are excited by projecting electromagnetic energy into the sample, terminating the projection of electromagnetic energy into the sample and measuring the characteristics of the decaying uranium phosphorescence after termination of the incident electromagnetic radiation.

Method for uranium determination

A method of detecting uranium compounds in an aqueous sample, containing uranium compounds that phosphoresce in response to ultraviolet light and other compounds which luminesce but have a shorter lifetime of phosphorescence than uranium compounds comprising the steps of increasing the phosphorescent characteristics of the uranium compounds and simultaneously diminishing the quenching efficiency of interfering ions in the sample by adding a polyphosphate compound and a buffer; projecting ultraviolet light into the sample; terminating said projection of ultraviolet light into the sample; measuring intensity of the decaying uranium phosphorescence at a time delay after the termination of the ultraviolet light, the time delay being longer than the time for luminescence due to materials other than uranium compounds possibly in the sample to substantially decay.

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Alliston, Canada

John C Robbins