Knowledge Bank

A new approach to the application of the equivalent width method was developed. In previous experiments the line intensities had been determined from a knowledge of $x2/x1$, where x is the parameter defined in the Landenburg-Reiche equation, and 1 and 2 refer to the different experimental conditions required for the determination. The methods used to accomplish this had been to use cells of different lengths, or to use gas mixtures of different compositions by varying the pressures of the absorber and foreign gas. Neither of these methods give rise to accurate values for the intensity. In this work the intensities were obtained from a knowledge of the maximum absorption coefficients for the case of pure HF, and the assumption that the intensity of a special line depended only on the amount of the absorber present, and was independent of the pressure of the broadening gas. The values obtained for the half-widths agreed closely with those obtained by using the line shape method. Thus experimental evidence was obtained which supports the assumption that the line intensity is dependent only on the amount of the absorber present. The line shapes were investigated for the lines which could be slit corrected. It was found that the Lorentz exponent changed from the value of 2.0 for the narrowest lines to a value of approximately 1.85 for the widest lines investigated. The deviations from Lorentz shape, in all cases, began where the half absorption half width was approximately 0.75 wavenumbers. The directly measured intensities of those lines which could be slit corrected agreed closely with the results from the equivalent width method, giving even stronger support to the assumption that the line intensity is dependent only on the amo*** *** the absorber present.