Large-sized and highly radioactive 3H and 109Cd Langmuir-Blodgett films

A device for the deposition of a radioactive Langmuir-Blodgett (LB) film was developed with the use of: (1) a modified horizontal lifting method, (2) an extremely shallow trough, and (3) a surface pressure-generating system without piston oil. It made a precious radioactive subphase solution repeatedly usable while keeping its radioactivity concentration as high as possible. Any large-size thin films can be prepared by just changing the trough size. Two monomolecular-layers of Y-type films of cadmium [3H] icosanoate and 109Cd icosanoate were built up as 3H and 109Cd β-sources for electron spectroscopy with intensities of 1.5 GBq (40 mCi) and 7.4 MBq (200 μCi), respectively, and a size of 65×200 mm2. Excellent uniformity of the distribution of deposited radioactivity was confirmed by autoradiography and photometry.