Anomalously large electrooptic response of water at the air-water interface

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K05134
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics I
• Research Institution: Tokyo University of Science
• Principal Investigator: Tokunaga Eiji 東京理科大学, 理学部第一部物理学科, 教授 (70242170)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 水 / 電気光学効果 / ポッケルス効果 / 気水界面 / 固液界面 / 水素結合 / 電気二重層

Outline of Final Research Achievements

We examined why the signal reproducibility is low about the Pockels effect of the air/water interface with an electric field vertical to the interface and clarified:
(1)When DC electric field is superimposed on AC field, signal is increased.(2)The lower the modulation frequency, the larger the signal.(3)There is a vertical movement of the water surface on the order of micrometer.(4)Since the signal is observed with a photodiode having a detection area larger than the probe beam size, there is a true Pockels effect due to the refractive index change at the air-water interface, not influenced by the vertical movement.It is found that water at the air-water interface shows an anomalously large Pockels effect with an electric field applied parallel to the interface,methanol and ethanol also have a large Pockels coefficient at the liquid-electrode interface,and the Pockels effect occurs in bulk water because the charged diffuse layer expands to bulk region under an AC electric field.

Free Research Field

光物性