Infrared absorption cross-sections and integrated absorption intensities for difluoromethane (HFC-32) and 1,1,1,2-tetrafluoroethane (HFC-134a) in the650-50 cm(-1) region

High-resolution (0.03 cm(-1)) infrared absorption cross sections and integr ated absorption intensities for difluoromethane (HFC-32) and 1,1,1,2-tetraf luoroethane (HFC-134a) are reported for the 50-650 cm(-1) spectral region. The data presented are for the pure vapour and for several mixtures with dr y air, at a series of temperatures between ca. 200 K and room temperature. The absorption cross sections were calculated with and without correction f or backward or sample emission, and it is shown that this correction can be important. The data are supported by ab initio calculations at a relativel y high level of theory. The effect of buffer gas pressure and temperature o n the integrated cross sections is discussed. (C) 2000 Elsevier Science Ltd . All rights reserved.