The construction and use of an electronic actinometer

Abstract

An electronic actinometer, adopting a dual-beam configuration and incorporating two UV enhanced silicon photodiodes which integrate the photon rate incident on each detector by means of a voltage-to frequency converter and a digital counter, was designed and built. With this type of configuration, the operation is based on measuring the difference in the light flux before and behind the sample vessel, consequently yielding a result independent of fluctuations in the intensity of the incident beam. Irradiations are confined to the near UV/violet domain (260-420nm) by selecting either of three filters each composed of a sequence of three inorganic salt solutions. Each combination of filter solutions permits the transmission of a fairly broad bandwidth (-60nm) of light. Thorough testing of the apparatus manifested excellent reproducibility and accuracy.