The vibrational and electronic features of propargyl chloride (HC C-CH2Cl) attached on the Si(1 0 0) - 2 x 1 surface have been investigated using high resolution electron energy loss spectroscopy (HREELS) and X-ray photoelectron spectroscopy (XPS). The disappearance of the C-Cl stretching mode and the existence of C-sp-H and -C C stretching modes in the HREELS spectra of chemisorbed molecules strongly demonstrate the cleavage of C-Cl bonds and the retention of -C CH linkage upon the chemisorption, further supported by the changes of the electronic features in chemisorbed XPS spectra. (C) 2009 Elsevier B. V. All rights reserved.