Detection of Iodine Atoms by an Atomic Fluorescence Technique: Application to Study of Diffusion and Wall Recombination

摘要

An atomic fluorescence method has been used to detect iodine atoms in concentrations lower than 1010/cm3. The heart of the apparatus is a ldquo;solarhyphen;blindrdquo; photomultiplier having practically no sensitivity to radiation of wavelengths longer than 2500 Aring;, but with good response in the region of the two strong iodine atomic resonance lines near 1800 Aring;. In combination with a small photolysis flashlamp, the system is used to study recombination of groundhyphen;statelpar;2P3sol;2rpar;iodine atoms in pure I2vapor. At pressures below 0.2 torr the removal of atoms is seen to be predominantly a firsthyphen;order diffusionhyphen;controlled process, characterized by a wall sticking probability of 0.040ndash;0.065 and a binary diffusion cross section of 100 Aring;2. The reaction Iplus;I2rarr;I3is found to be of minor significance in this study; a rough estimate indicates that fewer than one in 104Isngbnd;I2collisions lead to the formation of I3.