Temperature dependence of the absorption cross sections of formaldehyde between 223 and 323 K in the wavelength range 225–375 nm

UV absorption cross sections of formaldehyde (HCHO) have been measured with a spectral resolution of 0.025 nm in the wavelength range 225–375 nm at 298 K using a diode array detector. At selected temperatures ranging from 223 to 323 K, measurements have been conducted to obtain temperature gradients in the wavelength range 250–356 nm. Error limits for the reported absorption cross sections are ±5% but at least ±3×10 −22 cm 2 molecule −1 . For the temperature gradients, uncertainties are <8%. Spectra and temperature gradients are compared with earlier measurements.