Current Group Members
Postdoctoral Researchers
Dr. Fang Liu
Ph.D. from University of Pennsylvania
I am using femtosecond two-photon photoemission spectroscopy with extreme-UV lasers to explore electronic structure and dynamics of self-assembled semiconductors. In my spare time, I enjoy baking and feeding the other people you see on this webpage.
Email: fl2454@columbia.edu
Dr. Sebastian F. Maehrlein
Ph.D. from Free University of Berlin
My central research interest evolves around lattice-driven phenomena in solids to control material properties on ultrafast time scales. In my Ph.D. thesis at the Fritz-Haber-Institute of the Max Planck Society, I studied phonon driven spin dynamics and demonstrated a novel nonlinear light-matter coupling scheme by making use of intense THz-electric fields. Now, I investigate how specific lattice properties may lead to charge carrier protection and defect tolerance in emerging semiconductors. In my free time, I study spin properties of plastic discs or explore NY’s art scene.
Dr. Feifan Wang
Ph.D. from Peking University
I try to complete the solar-chemical energy conversion puzzle from the aspects of photophysics and surface/interface chemistry. During my PhD program, I studied the solid-state semiconductor nanomaterials for photocatalysis and photoelectrochemical cells, with focusing on material synthesis and performance characterization, more about the chemistry and molecular engineering. Here, I am establishing some fundamental understanding of photophysics in the novel optoelectronic materials through synthesizing andprobing the carrier screening in these model systems. After work, I like to jog, read, and learn cooking food.
Dr. Yusong Bai
Ph.D. from Duke University
During my Ph.D., my research emphasis was on interrogating and managing photo-induced electronically excited-state dynamics of various supermolecular to nanoscale structures, including ethyne-bridged highly-conjugated (porphinato)metal(II) architectures, semiconducting single-walled carbon nanotubes, etc. Currently, I investigate charge transfer dynamics at donor/acceptor interfaces.
Dr. Mark Ziffer
Ph.D. from University of Washington
My research focuses on using EUV time resolved two photon photoemission spectroscopy to study electronic structure and charge carrier dynamics in 2D semiconductor monolayers and heterostructures based on superatomic solids and transition metal dichalcogenides. I received my PhD from the University of Washington working with David Ginger, where I used electric field modulation spectroscopy and luminescence spectroscopy techniques to study exciton electronic structure and charge recombination in hybrid organic-inorganic perovskite and organic semiconductors. In my spare time I like exploring new places and trying new foods, which luckily NYC has no shortage of.
Dr. Doyk Hwang
Ph.D. from Seoul National University
In the XYZ Group, I am working on understanding the fundamentals of light-matter interactions, specifically exciton-polaritons in microcavities, with various spectroscopic techniques. During my Ph.D. with Prof. Seong Keun Kim, I was interested in photoexcited processes in organic molecules and photovoltaics which I investigated through the lens of femtosecond spectroscopic techniques including second-order nonlinear spectroscopy. In my free time I enjoy searching for good music, reading great literature, going to contemporary art museums, or just wandering through the beautiful parks of NYC.
Dr. Yanan Dai
Ph.D. from University of Pittsburgh
My PhD research was focused on imaging of femtosecond dynamics of space-time structured surface evanescent waves using interferometric time-resolved coherent multi-photon photoemission microscopy, and studying their physical properties such as spin angular momentum, field chirality and topological spin textures. Now I am trying to explore the rich electronic and excitonic properties of bilayer heterostructures composed of transition metal dichalcogenides, using time-resolved and angle-resolved photoemission spectroscopy with a femtosecond laser-based excitation source.
Dr. Qiuyang Li
Ph.D. from Emory University
I received my Ph.D. in Physical Chemistry focusing on the charge separation/recombination and exciton transport/dissociation in semiconductor nanocrystals for solar-to-hydrogen conversion and lasing applications. In the XYZ group, my research is mainly on ultrafast laser spectroscopic studies on exciton, electron, and phonon dynamics in new and emerging semiconductors. In my spare time, I enjoy movies, foods, badminton, and swimming.
Dr. Kihong Lee
Ph.D. from Columbia University
I was born and raised in South Korea. At U.C. Berkeley, I researched heterogeneous catalysis of metal nanoparticles under the guidance on Prof. Gabor Somorjai. I am studying superatom solids and their optical properties as a joint postdoc with Prof. Xiaoyang Zhu and Prof. Xavier Roy.
Dr. Yongping Fu
Ph.D. from the University of Wisconsin-Madison
My research interests are focused on the chemistry, physics, and optoelectronic applications of nanoscale and solid-state materials. I received a Ph.D. in chemistry from the University of Wisconsin-Madison (2018) and my B.S. degree in chemistry from Peking University (2012). During my Ph.D. study with Prof. Song Jin, I worked on the rational synthesis and optoelectronic applications of halide perovskite nanostructures (e.g. 1D nanowires and 2D quantum wells), phase stabilization of metastable perovskites, and discovery of new perovskite materials. After graduation, I held a postdoc with Prof. Elad Harel at Northwestern University, where I studied carrier dynamics in 2D perovskites and nanostructures using transient absorption microscopy. In the XYZ group, I am studying exciton-polaritons in semiconductor microcavities using various spectroscopic techniques. I also enjoy swimming, cooking, traveling and gardening.
Dr. Carmen Rubio Verdú
I am a joint postdoc with the Pasupathy Group in the Department of Physics. I use Low-temperature Scanning Tunneling Microscopy/Spectroscopy and am studying stronglycorrelated phenomena in bilayer 2D materials.
Graduate Students
Jue Wang
B.S. in Chemistry from Peking University
I use time-resolved optical spectroscopy and microscopy to study interlayer excitons in two-dimensional van der Waals heterostructures. Before this dimension reduction, I worked on hot carriers and polaron physics in lead halide perovskites. When getting my B.S. at Peking University, I researched single-molecule biophysics of DNA repair and met Rachael with whom I spend my spare time and travel around the world.
Email: jw3227@columbia.edu
Drew Schlaus
B.S. in Chemistry from University of Redlands
I investigate the fundamental light matter interactions in polariton condensates using kerr gated ultrafast time-resolved photo-luminescence microscopy. It was my initial love of photography which years ago sparked my interest in spectroscopy. I am still an avid photographer but you will frequently find me screeching karaoke, enjoying the baked deserts from fellow group members, exploring the New York city skyline, and adventuring through the frontiers of scientific research.
Email: as4942@columbia.edu
Michael Scott Spencer
B.S. in Chemistry & Physics from West Virginia University
I work on polariton lasing and the application of novel spectroscopic techniques. In my free time, I enjoy the outdoors, especially hiking.
Email: mss2257@columbia.edu
Felisa Conrad-Burton
B.S. in Chemistry from George Mason University
I use time-resolved optical techniques to explore and understand the fundamental processes of new singlet fission materials. I also enjoy taking full advantage of the variety of food and Broadway shows available in NYC, as well as fattening up my fellow group members with copious amounts of homemade pie.
Email: fsc2118@columbia.edu
Yufeng Liu
B.S. in Chemistry from Fudan University
I worked on infrared photodissociation spectroscopy of cluster ions during my undergraduate. Here, bidding farewell to the gas phase and entering the regime of solid state, I resume my connection with optical experiments and clusters by exploring the electron-phonon coupling in superatomic materials. You can constantly find my practicing the piano in the lounge after work
Email: yl3983@columbia.edu
Wenjing Wu
B.S. in Materials Science Engineering from East China University of Science and Technology
I am currently a Master’s student in the Materials Science and Engineering Department. During my undergrad at ECUST my study was mainly focused on inorganic materials. Here, I am working on two dimensional materials with rationale designed nanophotonic structures with Dr. Lin Zhou. Rock music and chocolate light up my life.
Past Group Members
Graduate Students
Prakriti Joshi (Ph.D., 2019) – Postdoc, University of Chicago (King Group)
Xinjue Zhong (Ph.D., 2018) – Postdoc, Princeton University (Kahn Group)
Tyler Evans (Ph.D., 2018) – Postdoc, UC Berkeley (Leone Group)
Timothy Atallah (Ph.D., 2017) – Postdoc, UCLA (Caram Group)
Kristopher Williams (Ph.D., 2017) – Postdoc, MIT (Tisdale Group)
Nicholas Monahan (Ph.D., 2015) – Rutherford Research Fellow, Victoria University of Wellington
Cory Nelson (Ph.D., 2015) – Intel Corporation
Xiaoxi Wu (Ph.D., 2015) – Postdoc, Stanford University (Lindenberg Group)
Kin-Wai Wesker Lei (Ph.D., 2014) – Novati Technologies Inc.
Adam Garland (Ph.D., 2014) – Water Lens, LLC
Joshua Morris (Ph.D., 2013) – Assistant Professor, Georgia Gwinnett College
John Tritsch (Ph.D., 2013) – Intel Corporation
Kenrick Williams (Ph.D., 2012) – Lecturer, Green River College
Williams Tisdale (Ph.D., 2010) – Associate Professor, MIT
Travis Mills (Ph.D., 2009) – Associate Professor, St. Paul’s College
Loren Kaake (Ph.D. 2009) – Assistant Professor, Simon Frasier University
Matthew Goertz (Ph.D., 2009) – Donaldson Company
Yang Deng (Ph.D., 2008) – L’Oreal
Chad Lindstrom (Ph.D., 2006) – Air Force Research Lab
Gregory Dutton (Ph.D., 2006) – National Institute of Justice (DOJ)
Taewoon Cha (Ph.D., 2005) – Apple, Inc.
Joo H. Kang (Ph.D., 2005) – Dow Chemical Company
Yong Seok Jun (Ph.D., 2004) – Associate Professor, Konkuk University, Korea
Ryan C. Major (Ph.D., 2003) – Hysitron, Inc.
Hanfu Wang (Ph.D., 2001) – Associate Professor, National Center for Nanoscience and Technology of China
Postdocs
Florian Geyer (2017-2018) – BASF
Kiyoshi Miyata (2015-2018) – Assistant Professor, Kyushu University (Onda Group)
Daniel Niesner (2014-2017) – Postdoc, University of Erlangen-Nuremberg (Fauster Group)
M. Tuan Trinh (2013-2016) – Adjunct Associate Research Scientist, University of Michigan (Rand Group)
Haiming Zhu (2014-2016) – Professor, Zhejiang University
Manuel Marks (2013-2015) – Bausch (Germany)
Heungman Park (2011-2013) – Assistant Professor, Texas A&M University-Commerce
Lei Shen (2009-2013) – Professor, Wuhan University of Technology
Wai-lun Chan (2009-2012) – Assistant Professor, University of Kansas
A. Jailaubekov (2009-2012) – Staff Scientist, Cymer Corporation
Manuel Ligges (2010-2011) – Univ. Essen, Germany
Luis Miaja-Avila (2010-2012) – NIST, Colorado
Abe Wolcott (2010-2012) – Assistant Professor, San Jose State University
Matthias Muntwiler (2005-2009) – Group Leader, Paul Scherer Institute, Switzerland
Qinxing Yang (2007-2009) – Associate Professor, Harbin Institute of Technology, China
Vassil Boiadjiev (2000-2002) – Lecturer, Temple University
Research Scientists
Lin Zhou (2018-2019) – Associate Professor, Nanjing University
