Sunscreen agents like Avobenzone and Octinoxate protect the skin from harmful ultraviolet UV radiation by absorbing the energy from UV rays and converting it into a less harmful form, such as heat. The photochemical mechanisms that allow these agents to absorb UV radiation involve electronic transitions within their molecular structures.1. Avobenzone: Avobenzone, also known as Parsol 1789 or butyl methoxydibenzoylmethane, is an oil-soluble organic compound that primarily absorbs UVA radiation 320-400 nm . Its effectiveness in absorbing UVA radiation is due to the presence of a conjugated system of double bonds and carbonyl groups in its molecular structure. When Avobenzone absorbs UVA radiation, its -electrons in the conjugated system get excited to a higher energy level. This process is called -* transition. Afterward, the excited electrons return to their ground state, releasing the absorbed energy in the form of heat or longer-wavelength radiation, which is less harmful to the skin.2. Octinoxate: Octinoxate, also known as Octyl methoxycinnamate or ethylhexyl methoxycinnamate, is an organic compound that is effective in absorbing UVB radiation 280-320 nm . Its molecular structure contains an ester linkage and a cinnamate group, which is responsible for its UV-absorbing properties. When Octinoxate absorbs UVB radiation, the electrons in the double bond of the cinnamate group undergo a transition called n-* transition. In this process, a non-bonding electron n-electron is excited to the * anti-bonding orbital. Similar to Avobenzone, the excited electrons in Octinoxate return to their ground state, releasing the absorbed energy as heat or longer-wavelength radiation.In summary, both Avobenzone and Octinoxate absorb harmful UV radiation through electronic transitions within their molecular structures. The primary difference between the two lies in the type of UV radiation they absorb and the specific electronic transitions involved. Avobenzone is more effective in absorbing UVA radiation through -* transitions, while Octinoxate is more effective in absorbing UVB radiation through n-* transitions. This complementary absorption profile makes them suitable for use together in broad-spectrum sunscreens, providing protection against both UVA and UVB radiation.