INTERFERENCE EFFECT OF ELECTRON-CAPTURE X-RAYS FROM AN I-125 LABELED PROTEIN MONOLAYER IN AN AQUEOUS-SOLUTION

We have measured the vertical distribution of a radioactively labeled protein in an aqueous solution by using the interference effect of ele ctron-capture X-rays from radioisotopes. This interference is between the direct monochromatic emission from radioactive atoms and the emiss ion totally reflected by the substrate surface. Structural information about radioactive atoms can be obtained by analyzing the measured int erference fringes, since the period of these fringes depends on the po sition of the radioactive atoms relative to the substrate surface. In this work we used bovine serum albumin radioiodinated with carrier fre e I-125 by using Chloramine T. The protein molecules were electrostati cally adsorbed in a monolayer form by the positively charged Langmuir layer at the air-water interface.