Measuring Line Centers from Digitally Recorded Spectra Using a Minicomputer

Abstract

A system is described for determining spectral positions from high resolution infrared spectra which have been recorded in digital form on magnetic tape. The system employs a minicomputer located in the laboratory and line centers are determined by an interactive procedure in which the operator makes judgments based on information displayed on the CRT screen of the computer. This information consists of the spectrum, a reflection of a local section of the spectrum at a vertical line through the center of the screen, a plot of the difference between the spectrum and its reflection, and the square of the area under the difference curve. Very high accuracy is demonstrated for locating the centers of single lines as well as the centers of the components of incompletely resolved double lines. Determinations of spectral positions (wavenumber calibration) parallel operations that were previously performed as batch jobs by a much larger computer. Spectral positions are determined by standard methods of calibration of interference fringes and interpolation.