Methods and devices for detecting the presence of a NO forming material (e.g., a material that can form, or is, a nitrogen monoxide molecule) are disclosed based on detection of fluorescence exhibited by NO molecules in a first vibrationally excited state of a ground electronic state. Such excited NO molecules can be formed, for example, when small amounts of explosives are photodissociated. By inducing fluorescence of the material, a distinct signature of the explosive can be detected. Such techniques can be performed quickly and with a significant standoff distance, which can add to the invention's utility. In another aspection of the invention, methods and apparatus for generating electromagnetic radiation are disclosed. Such methods and apparatus can be used in conjunction with any detection method disclosed herein.