Allene nu9 and nu10: Low-Temperature Measurements of Line Intensity

We report laboratory intensity measurements for the weak nu9 (998.8 cm-1) and intense nu10 (841.1 cm-1) bands of allene. Allene is predicted to be a constituent of Titan's atmosphere, and measurements of its abundance would yield important information about the atmospheric chemistry of that body. Spectra were obtained at a temperature of 200 K (approximating Titan conditions) using the high-resolution FTS instrument at Kitt-Peak National Observatory's McMath-Pierce observatory. A total of 505 nu9 and 687 nu10 line intensities were fit using a least-squares method to accurately determine two sets of transition dipole moments. Integrated band intensities computed utilizing the fitted parameters were found to be 36 +/- 4% cm-2 atm-1 and 301 +/- 4% cm-2 atm-1 for nu9 and nu10, respectively, at 200 K. Copyright 1999 Academic Press.