Time-of-flight study of photoinduced dynamics of copper and manganese phthalocyanine thin films on Si(111)

Abstract

Photoinduced fragmentation and desorption of species from copper phthalocyanine (CuPc) and manganese phthalocyanine 80 nm thick films deposited on Si(111) have been studied by means of atomic force microscopy and time-of-flight mass spectroscopy in an ultra-high vacuum chamber. The main fragments formed under the effect of low-fluence (1–3 mJ cm−2) nanosecond laser light with photon energies of 2.34 and 1.17 eV are the entire phthalocyanine molecule, molecular fragments, atomic Cu and Mn and a Si-substituted CuPc. The latter is presumably due to migration of the Si atom of the underlying support to the vacancy formed after photoejection of the metallic atom out of the phthalocyanine molecule. The mechanism of photofragmentation and desorption is essentially non-thermal involving the metal atom as a key factor.