S-1 <- S-0 hole-burning spectra have been measured for jet-cooled alpha, omega-dithienylethylene (DTE) and alpha, omega-dithienylbutadiene (DTB) vapors, along with the excitation and. uorescence spectra. The S1 origins of the two conformers of DTE vapor were observed at 28 648 and 28 966 cm(-1), which are assigned to those of the anti-syn and anti-anti forms, respectively. With DTB vapor, the apparent S1 origin of the main conformer (anti-anti) was observed at 25 471 cm(-1) and the S1 origin of the minor conformer was observed at 25 678 cm(-1). The minor conformer can be assigned to the anti-syn conformer. These results are in agreement with those obtained recently [T. Itoh, Y. Numata, J. Phys. Chem. A 113 (2009) 10160]. (C) 2010 Elsevier B. V. All rights reserved.