Optical second harmonic generation spectra in vacuum-deposited thin films of various phthalocyanines

✍ Scribed by Toshiki Yamada; Takaaki Manaka; Hajime Hoshi; Ken Ishikawa; Hideo Takezoe

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 126 KB
• Volume: 02
• Category: Article
• ISSN: 1088-4246
• DOI: 10.1002/(sici)1099-1409(199803/04)2:2<133::aid-jpp61>3.0.co;2-4

✦ Synopsis

We have observed fairly strong second-harmonic generation (SHG) in vacuum-deposited thin films of phthalocyanines (Pc) having central metal atoms; Co, Cu, Zn, VO, TiO, Pb, Sn and a metal-free Pc. Based on the remarkable spectral dependences, the SHG was concluded to be due to higher-order mechanisms: in all the films, a resonance peak due to an electric quadrupole transition was observed at the SH wavelength corresponding to the higher-energy side of the Q band. The spectral structures in the molecules with a similar shape are similar to each other, indicating that the electronic states responsible for the spectra are ascribed to Pc macrocycles. The w (2) values corresponding to w (2) zxx in C ?v symmetry and the conventional electric dipole mechanism are in the range of 1.4 $ 10 Â 10 À9 esu for these Pc films.