Abstract

We have observed ultrafast bleaching and induced absorption in MBE-grown chloro-indium-phthalocyanine (InPcCl) thin films. A 200-Å thick film was deposited using van der Waals molecular beam epitaxy onto a transparent tin disulfide substrate. RHEED measurements indicated epitaxy was maintained throughout sample growth. A comparison of linear absorption spectra for epitaxial versus polycrystalline InPcCl is shown in Figure 1. The Q-band absorption is significantly narrower for the epitaxial sample of Figure 1(a) with peaks at 760 nm and 680 nm compared to the extremely broad Q-band absorption for the 400-Å thick polycrystalline sample of Figure 1(b). The ultrafast measurements were performed using a CPM femtosecond laser system with a 620-nm pump and pulse widths of 80fs. The differential transmission (-Δαl) spectra were measured for various time delays between the probe and pump pulses.

© 1992 The Author(s)