Professional Education

  • Bachelor of Science, Massachusetts Institute of Technology (2016)
  • Doctor of Philosophy, University of California Berkeley (2022)
  • Ph.D., University of California Berkeley, Chemistry (2022)
  • B.S., Massachusetts Institute of Technology, Chemistry (2016)

Stanford Advisors

All Publications

  • Coherent Phonons in Antimony: An Undergraduate Physical Chemistry Solid-State Ultrafast Laser Spectroscopy Experiment JOURNAL OF CHEMICAL EDUCATION Porter, I. J., Zuerch, M. W., Baranger, A. M., Leone, S. R. 2022
  • Characterization of Carrier Cooling Bottleneck in Silicon Nanoparticles by Extreme Ultraviolet (XUV) Transient Absorption Spectroscopy JOURNAL OF PHYSICAL CHEMISTRY C Porter, I. J., Lee, A., Cushing, S. K., Chang, H., Ondry, J. C., Alivisatos, A., Leone, S. R. 2021; 125 (17): 9319-9329
  • Electron thermalization and relaxation in laser-heated nickel by few-femtosecond core-level transient absorption spectroscopy PHYSICAL REVIEW B Chang, H., Guggenmos, A., Cushing, S. K., Cui, Y., Din, N., Acharya, S., Porter, I. J., Kleineberg, U., Turkowski, V., Rahman, T. S., Neumark, D. M., Leone, S. R. 2021; 103 (6)
  • Layer-resolved ultrafast extreme ultraviolet measurement of hole transport in a Ni-TiO<sub>2</sub>-Si photoanode SCIENCE ADVANCES Cushing, S. K., Porter, I. J., de Roulet, B. R., Lee, A., Marsh, B. M., Szoke, S., Vaida, M. E., Leone, S. R. 2020; 6 (14): eaay6650


    Metal oxide semiconductor junctions are central to most electronic and optoelectronic devices, but ultrafast measurements of carrier transport have been limited to device-average measurements. Here, charge transport and recombination kinetics in each layer of a Ni-TiO2-Si junction is measured using the element specificity of broadband extreme ultraviolet (XUV) ultrafast pulses. After silicon photoexcitation, holes are inferred to transport from Si to Ni ballistically in ~100 fs, resulting in characteristic spectral shifts in the XUV edges. Meanwhile, the electrons remain on Si. After picoseconds, the transient hole population on Ni is observed to back-diffuse through the TiO2, shifting the Ti spectrum to a higher oxidation state, followed by electron-hole recombination at the Si-TiO2 interface and in the Si bulk. Electrical properties, such as the hole diffusion constant in TiO2 and the initial hole mobility in Si, are fit from these transient spectra and match well with values reported previously.

    View details for DOI 10.1126/sciadv.aay6650

    View details for Web of Science ID 000523302400013

    View details for PubMedID 32284972

    View details for PubMedCentralID PMC7124930

  • Differentiating Photoexcited Carrier and Phonon Dynamics in the Δ, <i>L</i>, and Γ Valleys of Si(100) with Transient Extreme Ultraviolet Spectroscopy JOURNAL OF PHYSICAL CHEMISTRY C Cushing, S. K., Lee, A., Porter, I. J., Carneiro, L. M., Chang, H., Zurich, M., Leone, S. R. 2019; 123 (6): 3343-3352
  • Real-Time Observation of a Coherent Lattice Transformation into a High-Symmetry Phase PHYSICAL REVIEW X Teitelbaum, S. W., Shin, T., Wolfson, J. W., Cheng, Y., Porter, I. J., Kandyla, M., Nelson, K. A. 2018; 8 (3)
  • Photoexcited Small Polaron Formation in Goethite (α-FeOOH) Nanorods Probed by Transient Extreme Ultraviolet Spectroscopy JOURNAL OF PHYSICAL CHEMISTRY LETTERS Porter, I. J., Cushing, S. K., Carneiro, L. M., Lee, A., Ondry, J. C., Dahl, J. C., Chang, H., Alivisatos, A., Leone, S. R. 2018; 9 (14): 4120-4124


    Small polaron formation limits the mobility and lifetimes of photoexcited carriers in metal oxides. As the ligand field strength increases, the carrier mobility decreases, but the effect on the photoexcited small polaron formation is still unknown. Extreme ultraviolet transient absorption spectroscopy is employed to measure small polaron formation rates and probabilities in goethite (α-FeOOH) crystalline nanorods at pump photon energies from 2.2 to 3.1 eV. The measured polaron formation time increases with excitation photon energy from 70 ± 10 fs at 2.2 eV to 350 ± 30 fs at 2.6 eV, whereas the polaron formation probability (85 ± 10%) remains constant. By comparison to hematite (α-Fe2O3), an oxide analogue, the role of ligand composition and metal center density in small polaron formation time is discussed. This work suggests that incorporating small changes in ligands and crystal structure could enable the control of photoexcited small polaron formation in metal oxides.

    View details for DOI 10.1021/acs.jpclett.8b01525

    View details for Web of Science ID 000448083300047

    View details for PubMedID 29985006