Quantum yields and photodissociation coefficients of acetaldehyde in the troposphere

The experimental data available for the photodissociation quantum yields of acetaldehyde are evaluated to derive formal expressions for their dependence on wavelength and pressure. The formulae are used to calculate the photodissociation coefficient of acetaldehyde as a function of altitude in the troposphere. The processes active in the photodecomposition of acetaldehyde are comparable to those in acetone, but the photodissociation coefficients of acetaldehyde (at room temperature) are six times greater. The dependence of the quantum yields on wavelength and pressure supports recent evidence of participation of both singlet and triplet states in the photodissociation process.