Excited-state molecular structures captured by X-ray transient absorption spectroscopy: A decade and beyond

Lin X. Chen, Xiaoyi Zhang, Jenny V. Lockard, Andrew B. Stickrath, Klaus Attenkofer, Guy Jennings, Di Jia Liu

Research output: Contribution to journalArticlepeer-review

62 Scopus citations


Transient molecular structures along chemical reaction pathways are important for predicting molecular reactivity, understanding reaction mechanisms, as well as controlling reaction pathways. During the past decade, X-ray transient absorption spectroscopy (XTA, or LITR-XAS, laser-initiated X-ray absorption spectroscopy), analogous to the commonly used optical transient absorption spectroscopy, has been developed. XTA uses a laser pulse to trigger a fundamental chemical process, and an X-ray pulse(s) to probe transient structures as a function of the time delay between the pump and probe pulses. Using X-ray pulses with high photon flux from synchrotron sources, transient electronic and molecular structures of metal complexes have been studied in disordered media from homogeneous solutions to heterogeneous solution-solid interfaces. Several examples from the studies at the Advanced Photon Source in Argonne National Laboratory are summarized, including excited-state metalloporphyrins, metal-to-ligand charge transfer (MLCT) states of transition metal complexes, and charge transfer states of metal complexes at the interface with semiconductor nanoparticles. Recent developments of the method are briefly described followed by a future prospective of XTA. It is envisioned that concurrent developments in X-ray free-electron lasers and synchrotron X-ray facilities as well as other table-top laser-driven femtosecond X-ray sources will make many breakthroughs and realise dreams of visualizing molecular movies and snapshots, which ultimately enable chemical reaction pathways to be controlled.

Original languageEnglish (US)
Pages (from-to)240-251
Number of pages12
JournalActa Crystallographica Section A: Foundations of Crystallography
Issue number2
StatePublished - 2010


  • Dynamical structural science
  • Excited-state metalloporphyrins
  • MLCT state structures
  • Ultrafast X-ray sciences
  • X-ray transient absorption spectroscopy
  • XTA

ASJC Scopus subject areas

  • Structural Biology

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