Thermal and Photoinduced Covalent Attachment of 3-Chloro-1-propanol on Si(100)-2×1

Abstract

3-Chloro-1-propanol (HO−CH2−CH2−CH2−Cl) covalently binds onto Si(100)-2×1 through the thermal dissociation of the OH group to form Si−O−CH2−CH2−CH2−Cl surface intermediates, evidenced by the appearance of the Si−H stretching mode (2110 cm−1) and the retention of C−Cl stretching mode (654 cm−1) in the high-resolution electron energy loss spectroscopy (HREELS) spectrum of chemisorbed 3-chloro-1-propanol molecules and the chemical downshift of O1s binding energy (BE) in the X-ray photoelectron spectroscopy (XPS) study. The C−Cl bonds in the chemisorbed 3-chloro-1-propanol can be cleaved upon 193 nm irradiation, resulting in Si−O−CH2CH2CH2−CH2CH2CH2−O−Si through lateral diradical coupling. Upon covering the chemisorbed 3-chloro-1-propanol with physisorbed molecules, photoinduced diradical coupling between physisorbed and chemisorbed molecules was also evidenced, achieving the secondary attachment of 3-chloro-1-propanol on the Si surface and forming Si−O−CH2CH2CH2−CH2CH2CH2−OH.