Argon vacuum wave-length measurements

Abstract

The vacuum wave-lengths of 84 lines of the argon spectrum in the region 3500 to 4500 Å have been measured using two reflecting echelons. Since the standard error of the most favourable lines is only ± 0·0001 Å and less than ± 0·0002 Å for 53 of the lines, there is some justification in expressing the wave-lengths to eight significant figures. As no systematic difference between wave-lengths determined with each echelon has been found, the method is independent of the particular instrument employed. A discussion of the non-linearity of dispersion is given, and it is shown that it may be assumed linear for the particular echelons used without introducing appreciable error.