Abstract-Evaluation of hydrogen-bonding distance in organic nonlinear optical crystals for high-output terahertz-wave generation

• Takeshi Matsukawa^a,  
• Akinori Hoshikawa^a, 
• Yoshihisa Ishikawa^b, 
• Toru Ishigaki^a

• ^a Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai, Ibaraki, 319-1106, Japan
• ^b Institute of Material Structure Science, KEK Tokai, 203-1 Shirakata, Tokai, Ibaraki, 319-1106, Japan

Received 22 August 2016, Revised 4 January 2017, Accepted 5 January 2017, Available online 6 January 2017

http://www.sciencedirect.com/science/article/pii/S0022286017300261

The crystal structure of deuterated 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST-d₂₆) was obtained by powder X-ray and neutron diffraction measurements. The scattering length density distributions of deuterium atoms were successfully obtained from neutron diffraction data using the maximum-entropy method. From the density distributions, we estimated the hydrogen-bonding distances, which contribute significantly to the vibrational modes of DAST at 1 THz. Inhibition of these hydrogen bonds could allow the development of new nonlinear optical materials with low THz absorption.