Knowledge Bank

Resolution of about $0.1cm-1$ has been obtained in the 8-14 micron range with the grating spectrometer built by Hardy in 1932. This is within a factor of two of the Rayleigh limit for the diffraction grating used, and compares to previous values between 0.25 and $0.33cm-1$. Part of the improvement results from the elimination of spurious noises in the amplifying system, particularly in the Firestone photoelectric preamplifier; and part from a new 2400-line-per-inch diffraction grating that is considerably superior to previous ones ruled here. Results on the 10-micron absorption band of ammonia will be shown.