Large second harmonic generation from mixtures of para-nitroaniline and its N-alkyl derivatives

Abstract

We have investigated nonlinear organic mixtures of para-nitroaniline (p-NA) and its N-alkyl derivatives, by measuring the second harmonic generation (SHG) from the powder samples. The SHG powder test shows that the mixtures of p-NA and N-isopropyl-4-NA (Pr iNA) or N-n-propyl-4-NA (Pr nNA) or N-n-butyl-4-NA (Bu nNA) have exceedingly large SHG activity, although the individual compound has relatively small or no SHG activity. The measured SHG intensities of the three mixtures come up to the maximum values of 416, 270, and 271 times larger than that of urea, when the mixing weight ratios to p-NA are 0.5, 0.1, and 0.05, respectively. That is, the mixture of Pr iNA and p-NA is found to have second largest powder efficiency reported to date. This result indicates a new direction in the field of co-crystallization of organic molecules to generate highly nonlinear organic crystals.