Laser trapping and spectroscopy of single water droplets as a model reaction system of cloud droplets in the atmosphere

2015 Fiscal Year Final Research Report

• Project/Area Number: 25410144
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Analytical chemistry
• Research Institution: Hiroshima University
• Principal Investigator: Ishizaka Shoji 広島大学, 理学(系)研究科(研究院), 准教授 (80311520)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: レーザー捕捉法 / 顕微ラマン分光法 / エアロゾル

Outline of Final Research Achievements

Micrometer-sized water droplets are very important as a model reaction system of cloud droplets. There are many unsolved issues related to the nucleation and growth of cloud droplets in the atmosphere. Therefore, significant uncertainties are associated with the representation of clouds, and in the resulting cloud responses to climate change. In order to investigate the physical and chemical properties of single water droplets in air as a function of the droplet size or solute concentration, laser trapping experiments were conducted under controlled humidity conditions. In this study, we developed a trapping chamber equipped with a relative humidity controller and demonstrated the reversible control of the equilibrium size of a single droplet levitated in air through a change in relative humidity. Furthermore, chemical composition, diameter and temperature of individual water droplets were successfully determined by means of Raman spectroscopy.

Free Research Field

分析化学、光化学