Sperm fluoresces blue under ultraviolet (UV) light, specifically between 300-450 nm.
Here's a more detailed explanation:
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Fluorescence: The phenomenon of fluorescence occurs when a substance absorbs light (in this case, UV light) and then emits light of a different, often longer, wavelength. This emitted light is what we perceive as color.
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UV Light Spectrum: UV light is a part of the electromagnetic spectrum with wavelengths shorter than visible light. Different UV wavelengths can cause different substances to fluoresce with different colors.
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Sperm Composition: The components of semen that cause it to fluoresce blue under UV light are complex and not fully understood.
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Forensic Applications: The fluorescence of semen under UV light is a valuable tool in forensic science for identifying and locating semen stains, especially dried stains, at crime scenes. Most bodily fluids need to be dry to fluoresce; however, urine can fluoresce in its liquid state.
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Practical Considerations: For best results in forensic applications, the area being examined is typically darkened, and a UV light source is used to illuminate potential stains. The blue fluorescence, if present, provides an initial indication of the possible presence of semen.
