title: Calibration of far-infrared spectrometers in the 100-200-cm(-1) region with the nu(5)-nu(4) band of acetylene.
abstract: The R branch of the nu(5)-nu(4) difference band of acetylene, 12C(2)H(2), is recommended as a calibration standard for the 100-200-cm(-1) region. The lines are split by l-type doubling into pairs with a 3:1 intensity ratio, but this can only be observed under high resolution. The position of the calculated maximum of each blended line contour is displaced by the l-type doubling from the accurately calculated wavenumber of the more intense component of each J pair, but not by more than one-fifteenth of the spectral slit width. It is recommended that values calculated from constants derived from high resolution mid-ir measurements be used for calibration.
authors.forename: D B
authors.initials: DB
authors.lastname: Braund
authors.forename: A R
authors.initials: AR
authors.lastname: Cole