John F. Kielkopf's research while affiliated with University of Louisville and other places

An approximation to the Voigt function is described, which is valid over the entire domain of the independent variables that characterize it and which is accurate to the order of 0.0001 of the peak value of the function. Relations between the parameters of the function are also given. The approximation is used to develop a procedure for fitting observed lines with Voigt functions; the class of asymmetric lines that arise from the superposition of two Voigt functions is considered in some detail, and methods for extracting the Voigt parameters of the components from the observed contour of the envelope are given. The measurement of the width and shape of a single line with a Fabry-Perot interferometer is also discussed. All of the calculations described here can be handled by programmable calculators or small computers.