Infrared heterodyne spectroscopic measurements of transition frequencies and intensities of ethylene and isotopic ethylene ((C12CH4)-C-13) between 840 and 980 cm(-1)

Infrared heterodyne spectroscopy (lambda/Delta lambda greater than or equal to 10(6)) enabled the precision measurement of lineshapes of 168 ethylene absorption transitions for (C2H4)-C-12 and 88 absorption transitions for C- 13 (CH4)-C-12. Of the 168 (C2H4)-C-12 transitions, 96 are assigned to nu (7 ), 17 to nu (10), 10 to nu (4), and 45 to hotband transitions. The 88 C-13 (CH4)-C-12 transitions have not been assigned. Measurements were made at ga s temperatures in the range of 293-297 K and at pressures in the range of 0 .05-0.5 Torr. Absolute line frequencies and line intensities were retrieved for each of the transitions. Frequencies and absolute intensities of unble nded strong lines were determined to better than 5 x 10(-5) cm(-1) and 10%, respectively. (C) 2001 Elsevier Science Ltd. All rights reserved.