An Improved Liquid Cell Cap for X-Ray Fluorescence Analysis
The liquid sample cell available from Siemens Corporation for use in their SRS-1 x-ray fluorescence analysis unit is particularly well designed in that a thin, widely spaced, nickel grid is provided for supporting the Hostaphan or Mylar foil upon which the liquid rests. This grid reduces the chance that the foil will break while in use and also keeps the liquid surface at a fixed position in the spectrometer as there is no opportunity for the foil to sag. The liquid sample cell, as supplied, has the disadvantage that the foil, which is held in place by being sandwiched between two O rings, is inclined to crumple when the end cap is tightened. A separate intermediate metal cap has now been designed to hold the grid and foil against one O ring and a modified plastic sleeve. The modified end cap is screwed against this intermediate cap; with this construction, no distortion of the foil occurs. Because of the reduced forces on the foil during the tightening of the end cap, it has been found possible to use a thinner foil: 6 μ rather than the 15 μ normally supplied by the manufacturer.