Electromagnetic waves (or electromagnetic radiation) are waves created by oscillating magnetic and electric fields, and include radio waves, microwaves, infrared, ultraviolet, visible light, X-rays and gamma rays. Similar to all waves, they carry energy, while this energy can be of very high intensity. In such a way, these waves have a huge area of use, including Forensic Science.
Explaining how Forensic Science uses different spectral methods, it can be said that conducting a forensic medical examination, spectral methods can answer many questions. For instance, according to Horswell (2004), they are used for spectral determination of the presence of blood and sperm stains; identification of blood traces, as well as traces of blood on mottled, dark and contaminated objects. Spectral methods allow an expert to identify the authenticity of works of art and detect falsification. However, this type of expertise is a separate field of study.
Giving some specific examples, it can be said that the ability of infrared rays to be absorbed and reflected by various substances to varying degrees is mainly used in Forensic Science. For example, they are strongly absorbed by graphite, soot, ink, and printing ink. Moreover, they are well reflected by white paper and penetrate through thin layers of aniline dyes, ebonite, and blood stains. Therefore, if the text of the document is made in pencil, ink, printing ink or with copy paper and crossed out with synthetic ink or covered with blood, it can be revealed through examination in reflected infrared rays. This method can also reveal traces of a close shot in the form of powder on a black object, colored with aniline dye, to differentiate objects of the same kind, absorbing and reflecting infrared rays to varying degrees. Making such a study of a forensic object, it is usually illuminated with an electric incandescent lamp. The results of the study in the reflected infrared rays are recorded photographically or directly perceived using an electron-optical converter.
expert practice, cases of application of a complex of research methods are
frequent. In the production of complex and commission expertise, each expert
can apply various methods. Nevertheless, even when the examination is carried
out individually, the expert can apply a set of complementary methods of one or
different areas of knowledge, and the use of spectral analysis plays a very
significant role. In such a way, the integration of knowledge leads not only to
the integration of sciences, but also to the integration of their methods,
which is particularly evident in the production of examinations.
Horswell, J. (2004). The Practice of Crime Scene Investigation. Taylor & Francis.