Pengfei Liu is a graduate student (2011-2017). Pengfei's research focuses on the physical properties of secondary organic material, and their influences on Earth's climate and atmospheric photochemistry. He developed an experimental method to obtain the wavelength-dependent complex refractive indices of secondary organic material using a spectroscopic ellipsometer. His recent studies employ a quartz-crystal microbalance to measure the volatility and the condensed-phase diffusivities. He is a recipient of the NASA Earth and Space Science Fellowship (NESSF). Prior to coming to Harvard, Pengfei earned a BS degree in Atmospheric Sciences and an MS degree in Atmospheric Physics & Environment, both from Peking University, China.