If the top of the intensity profile is flat, you've over-exposed. Erase the screen for the maximum erasure time and do a shorter exposure. The exception is tritium, which because of its low energy, requires a special uncoated screen. But take care not to contaminate your storage phosphor screen with 14 C. Make sure that your TLC plate is absolutely dry before starting your exposure, and place a sheet of Mylar between the TLC plate and the storage phosphor screen. Latent images are formed on storage phosphor screens during exposure to ionizing radiation.
Chemiluminescent reactions yield visible light, which erases latent images from the screens.
For nonradioactive imaging, Molecular Dynamics recommends chemifluorescence. Chemifluorescent blots are read directly in FluorImager and Storm imaging systems for maximum quantitative accuracy. Screens are not harmed by brief exposure to neutral aqueous solutions, but for wet gel exposures, the gel should be blotted free of excess buffer and wrapped in plastic wrap to prevent prolonged contact between the gel buffer and the screen. A. A PhosphorImager Count is an arbitrary unit of measure that describes the intensity of photon emissions released from the storage phosphor screen during scanning. The linear dynamic range of PhophorImager systems begins at one PhosphorImager Count.