Spectral bandwidth standard based on symmetrical absorption bands of a crystal standard

A calibration procedure of spectral bandwidth of high- resolution spectrophotometers recurring to the symmetrical absorption bands of a crystal standard is described. The method involves spectral line shape fitting followed by convolution with the slit function of the spectrophotometer. A calibration curve on transmittance versus spectral bandwidth is provided for practical and accurate metrological verification of the actual spectral bandwidth of the spectrophotometer. Results will be provided on the testing of the method on an intercomparison of spectral bandwidth calibration involving twenty laboratories.