The Use of Term-Value Fits in Testing Spectroscopic Assignments

✍ Scribed by J.K.G. Watson

• Book ID: 102600132
• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 375 KB
• Volume: 165
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.1994.1130

✦ Synopsis

The use of a least-squares term-value fit of a spectrum as a means of testing assignments is described. In a direct term-value fit the normal matrix is singular, with one zero eigenvalue for each set of connected levels. These equations are solved by a method which gives the term values of each connected set relative to their mean. The standard deviation (\sigma) from a term-value fit should be equal to the measurement error. It is shown that, as a test of individual assignments. it is possible to calculate from the results of a fit the fractional change (\tau_{i}=\left(\sigma_{i}-\sigma\right) / \sigma) when each line (l) is omitted singly from the fit. Anomalously large negative values of (\tau_{l}) indicate lines that may be misassigned or mismeasured. As an example, it is shown that the standard deviation of an unweighted term-value fit of a published compilation of 294 lines of the (\mathrm{H}_{3}^{+})ion can be reduced from (0.031 \mathrm{~cm}^{-1}) to (0.004 \mathrm{~cm}^{-1}) by the omission of 7 lines. ci 1994 Academic Press. Inc.