Third-order nonlinear optical study on sublimated/Langmuir-Blodgett thin films of lanthanide porphyrin phthalocyanine dimer/heterodimer and symmetric trimer systems by time-resolved non-degenerate four-wave mixing

Abstract

Time-resolved four-wave mixing (TRFWM) studies have been carried out on sublimated films of the neodymium phthalocyanine dimer Pc[superscript 2-Nd[superscript III]Pc[superscript point], the cerium porphyrin phthalocyanine sandwich mixed heterodimer Pc[superscript 2-]Ce[superscript IV]TPP[superscript 2-], the cerium porphyrin phthalocyanine symmetric trimer TPP[superscript 2-]Ce[superscript III]Pc[superscript 2-]Ce[superscript III]TPP[superscript 2-], the neodymium porphyrin phthalocyanine trimer Pc[superscript 2-]Nd[superscript III]TPP[superscript 2-]Nd[superscript III]Pc[2-], and Langmuir-Blodgett films of the cobalt porphyrin phthalocyanine mixed dimer CoPC [subscript 22][superscript 4+] / H[subscript 2]PcTS [subscript 4-]. In this work, we have presented a number of novel results: the first non-degenerate time-resolved four-wave mixing (NDTRFWM) experiment on a sublimated film, the first observation and identification of the diffusion contribution to the degrating process, the first observation and identification of photorefractive effect in an organic multimer thin film, and the first observation and identification of a correlated phonon mode shifting phenomenon. The absolute values of the third-order nonlinear optical susceptibility [chi superscript (3)] of the samples have been determined by comparing the third-order nonlinear optical responses of the samples with those of a slide of reference fused quartz under the same experimental conditions. It is shown that TRFWM is a very useful, very sensitive and very powerful tool to investigate the dynamics of the third-order nonlinear optical processes in a medium, especially those that can not be detected by transient absorption and other means of probing nonlinear optical properties. Through this work, it can be seen that lanthanide porphyrin phthalocyanine dimer/heterodimer trimer/heterotrimer systems could be a new family of organic materials most promising for the investigation and the applications of photorefractive effect. They are very versatile and have a great potential as nonlinear optical materials.