Photoreactive

Photoreactive describes a substance or material that undergoes a chemical or physical change upon exposure to light, particularly within a specific wavelength range. This change can manifest as a shift in color, a change in solubility, the creation of new compounds, or the release or absorption of energy. The extent and nature of the photoreactivity are dependent on factors such as the light's intensity, duration, and wavelength, as well as the material's chemical structure and surrounding environment. Photoreactivity has diverse applications spanning from light-sensitive materials to chemical transformations and scientific analysis.

Photoreactive meaning with examples

• Sunlight causes the photoreactive dye in the t-shirt to fade over time. Prolonged sun exposure breaks down the dye molecules, a form of photochemical degradation that changes the shirt's color. This process demonstrates a practical example of photoreactivity, highlighting its impact on everyday objects and how light can affect the composition of materials.
• In the lab, researchers used a photoreactive compound to create a photoswitch that can reversibly change its state when illuminated with specific wavelengths of light. This compound changes its molecular structure, allowing for very rapid switching. This control by light enables control over electric currents and can lead to advances in electronics.
• Certain photoreactive polymers are used in the manufacturing of photoresist materials for creating microchips. These polymers undergo crosslinking or decomposition when exposed to ultraviolet light, enabling precise patterns to be etched onto silicon wafers. Without this precise use of the polymer, the scale of microchips would be impossible.
• Photoreactive inks can be used in security applications such as marking currency and documents. Exposure to UV light will cause the photoreactive ink to glow or display a hidden image. Counterfeiting is more difficult when documents use unique inks which show verification only when exposed to very specific wavelengths.