Today photochemistry has become one of the most powerful research tool. Compounds of different molecules are occurred through various photochemical reactions like CO<sub>2</sub>, NH<sub>3</sub> and methane. Other examples of photochemical reactions are formation of O<sub>3</sub>, smog, Vitamin D and many more. A new field in photochemistry called photobiology helps us to understand the mechanism of photosynthesis (process by which plants make their own food by the absorption of sunlight).
Also photochemistry helps us to form some typical compounds like D<sub>2</sub>, cubanes, and several cleaning agents which all are made by various chemical reactions of photochemistry. The formation of laser light is only possible through photochemistry. LASER stands for Light Amplification by Stimulated Emission of Radiations. LASER contain monochromatic rays with coherent radiations, these rays can be easily focused to a small point. Due to this property, LASER light is used for cutting hard material like metal, diamond etc, also there is some application of LASER light in medical field.