The present invention provides methods for detecting electromagnetic energy (e.g., ultraviolet radiation) and articles suitable for use in such methods. The methods and articles can be useful for detecting sterilization or disinfection resulting from electromagnetic energy such as ultraviolet C. Detection of the sterilization or disinfection allows discontinuation of the exposure when a desired level of sterilization or disinfection has been obtained. Feedback mechanisms for controlling exposure to the energy may also be used.