Early history of X-ray Spectroscopy in the U.S. X-ray spectroscopy

the continuous x-spectrum emitted tube irradiates specimen , excites characteristic spectral x-ray lines in specimen. each of 92 elements emits characteristic spectrum. unlike optical spectrum, x-ray spectrum quite simple. strongest line, kalpha line, lalpha line, suffices identify element. existence of particular line betrays existence of element, , intensity proportional amount of particular element in specimen. characteristic lines reflected crystal, analyzer, under angle given bragg condition. crystal samples diffraction angles theta rotation, while detector rotates on corresponding angle 2-theta. sensitive detector, x-ray photons counted individually. stepping detectors along angle, , leaving in position known time, number of counts @ each angular position gives line intensity. these counts may plotted on curve appropriate display unit. characteristic x-rays come out @ specific angles, , since angular position every x-ray spectral line known , recorded, easy find sample s composition.

a chart scan of molybdenum specimen shown in fig. 2. tall peak on left side characteristic alpha line @ 2 theta of 12 degrees. second , third order lines appear.

since alpha line line of interest in many industrial applications, final device in norelco x- ray spectrographic instrument line autrometer. device programmed automatically read @ desired 2 theta angle desired time interval.

soon after autrometer introduced, philips decided stop marketing x-ray instruments developed in both u.s. , europe , settled on offering eindhoven line of instruments.

in 1961, during development of autrometer, norelco given sub-contract jet propulsion lab. lab working on instrument package surveyor spaceship. composition of moon’s surface of major interest , use of x-ray detection instrument viewed possible solution. working power limit of 30 watts challenging, device delivered wasn’t used. later nasa developments did lead x-ray spectrographic unit did make desired moon soil analysis.

the norelco efforts faded use of x-ray spectroscopy in units known xrf instruments continued grow. boost nasa, units reduced handheld size , seeing widespread use. units available bruker, thermo scientific, elvatech ltd. , spectro.