Knowledge Bank

Rotationally resolved infrared spectra of jet-cooled 1-butyne and of jet-cooled ethanol were recorded in the methyl C-H stretch region (near $2990-cm-1$) by direct absorption. A two-spherical-mirror multiple pass cell was used to enhance absorption of the Burleigh FCL 20 laser beam. To reduce thermal congestion, spectra were recorded at rotational temperatures as low as 0.75 K. For 1-butyne, a c-type band and an a,b-type hybrid band are assigned. For ethanol preliminary spectra show a c-type band.