Academic Profile

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Assoc Prof Loh Zhi Heng
Associate Professor, School of Physical & Mathematical Sciences - Division of Chemistry & Biological Chemistry
Assistant Chair (Academic), School of Physical and Mathematical Sciences (SPMS)

The central theme of our experimental research program is the study of coherent electron and nuclear dynamics in molecules and nanomaterials. Coherent electron motion and the ensuing quantum dynamics set forth by either optical excitation or nonresonant strong-field ionization with few-cycle laser pulses will be probed with attosecond to femtosecond time resolution. This proposed work builds upon my previous work, in which coherent electron motion in Kr+ ions that accompanies the formation of a spin-orbit wave packet is observed (Nature, 2010).

The main experimental techniques that are employed include attosecond time-resolved core-level transient absorption and transient photoelectron spectroscopies, in which soft x-ray pulses produced in a tabletop setup by high-order harmonic generation are used as probe. These soft x-ray studies are complimented with optical pump-probe measurements employing few-cycle (~5 fs) laser pulses. The ultimate goal of our studies is to exploit quantum coherences to enhance the performance of nanoelectronics and artificial light harvesting systems.
 
  • Coherent Quantum Dynamics Probed By Femtosecond Soft X-Ray Spectroscopy

  • Imaging The Femtosecond Carrier Dynamics Of 2D Heterostructures On The Nanoscale

  • Ultrafast Electron and Ion Dynamics of Ionized Liquid Water Probed by Femtosecond X-Ray Free-Electron Lasers
 
  • Zhaogang Nie, Run Long, Linfeng Sun, Chung-Che Huang, Jun Zhang, Qihua Xiong, Daniel W. Hewak, Zexiang Shen, Oleg V. Prezhdo, Zhi-Heng Loh. (2014). Ultrafast Carrier Thermalization and Cooling Dynamics in Few-Layer MoS2. ACS Nano, 8, 10931-10940.

  • Stephen R. Leone, C. William McCurdy, Joachim Burgdörfer, Lorenz S. Cederbaum, Zenghu Chang, Nirit Dudovich, Johannes Feist, Chris H. Greene, Misha Ivanov, Reinhard Kienberger, Ursula Keller, Matthias F. Kling, Zhi-Heng Loh, Thomas Pfeifer, Adrian N. Pfeiffer, Robin Santra, Kenneth Schafer, Albert Stolow, Uwe Thumm and Marc J. J. Vrakking. (2014). What Will It Take to Observe Processes in ‘Real Time’?. Nature Photonics, 8, 162-166.

  • Zhaogang Nie, Run Long, Jialin Li, Yi Ying Zheng, Oleg V. Prezhdo, and Zhi-Heng Loh. (2013). Selective Excitation of Atomic-Scale Dynamics by Coherent Exciton Motion in the Non-Born−Oppenheimer Regime. Journal of Physical Chemistry Letters, 4, 4260−4266.

  • Jialin Li , Zhaogang Nie , Yi Ying Zheng , Shuo Dong , and Zhi-Heng Loh. (2013). Elementary Electron and Ion Dynamics in Ionized Liquid Water. Journal of Physical Chemistry Letters, 4, 3698-3703.

  • Zhi-Heng Loh, Stephen R. Leone. (2013). Capturing Ultrafast Quantum Dynamics with Femtosecond and Attosecond X‑ray Core-Level Absorption Spectroscopy (Invited Perspectives Article). Journal of Physical Chemistry Letters, 4, 292-302.