About

Philip Bucksbaum holds the Marguerite Blake Wilbur Chair in Natural Science at Stanford University, with appointments in Physics, Applied Physics, and Photon Science at SLAC. He conducts research in the Stanford PULSE Institute, focusing on laser interrogation of atoms and molecules to explore and image structure and dynamics on the femtosecond scale. His work involves the development and application of ultrafast lasers to control quantum systems and to study atomic and molecular processes. Bucksbaum earned his Ph.D. in Physics from the University of California, Berkeley in 1980, after completing his A.B. at Harvard University in 1975. His early research included atomic parity violation experiments and co-authoring a textbook on weak interactions of leptons and quarks. He worked at Bell Laboratories starting in 1981, where he pursued applications of ultrafast coherent radiation, including time-resolved VUV ARPES and strong-field laser-atom physics. In 1990, he joined the University of Michigan, where he became Otto Laporte Collegiate Professor and later Peter Franken University Professor, and was founding Director of FOCUS, a National Science Foundation Physics Frontier Center. There, he pioneered research using ultrafast lasers to control quantum systems and launched experiments in ultrafast x-ray science at the Advanced Photon Source. In 2006, Bucksbaum moved to Stanford and SLAC, organizing the PULSE Institute to develop research utilizing the world’s first hard x-ray free-electron laser, LCLS. He has served as Department Chair of Photon Science and Division Director for Chemical Science at SLAC. His research continues to focus on laser-based techniques to image and understand atomic and molecular dynamics. He has authored more than 250 publications, is a Fellow of the APS and the Optical Society, and has been elected to the National Academy of Sciences and the American Academy of Arts and Sciences. Bucksbaum has received numerous honors, including the Norman F. Ramsey Prize, and has served as President of the Optical Society and the American Physical Society.

Research topics

• Physics
• Atomic physics
• Optics
• Quantum mechanics

Selected publications

• Fragmentation Dynamics of CS$_2$ Dications and Trications Following S 2p Ionization

  AIP Publishing · 2026-01-01

  otherOpen access

  We present the results from a detailed study of the fragmentation dynamics of CS$_2^{2+}$ and CS$_2^{3+}$, formed in intense femtosecond soft X-ray pulses above the sulfur 2p edge, primarily through single core photoionization from the S 2p site, and subsequent Auger-Meitner decay(s). By combining three-dimensional velocity map imaging with covariance analysis, we determine the relative momenta of the ions produced in each two- and three-body fragmentation channel, at significantly higher ion count rates than conventional coincidence measurements. We shed new light on the wide range of fragmentation channels observed from the CS$_2$ dication and trication, including channels that involve ionization-induced bond formation and fragmentations producing undetected neutral cofragments. In the latter case, a `native frames' approach is used to isolate contributions from concerted and sequential fragmentations and extract dynamical information about each step of a concerted fragmentation process. While dications often fragment sequentially, the trication is dominated by concerted fragmentation. The main trication fragmentation channel into S$^+$+ C$^+$+ S$^+$ can be well-approximated by classical Coulombic simulations of the ground-state geometry distribution, reflecting both the nature of the trication potential energy surface and the rapid multiple ionization prior to substantial structural dynamics. This study demonstrates ways in which fundamental insights into the fragmentation dynamics of polycations following X-ray ionization may be extracted, as will beneficial to future studies that employ time-resolved X-ray Coulomb explosion imaging to study ultrafast photochemistry.

  PublisherDOI

• Imaging Three-Dimensional Molecular Structure and Dynamics with Multiparticle Covariance and Cumulant Coulomb Explosion Analysis

  The Journal of Physical Chemistry Letters · 2026-03-10

  articleOpen access

  Coulomb explosion imaging (CEI) provides a direct means of imaging molecular geometry by correlating fragment ion momenta following the fragmentation of a molecular polycation. Here, we demonstrate the use of three-body covariance and four-body cumulant analysis to extract three-dimensional (3D) structural information from the X-ray-induced Coulomb explosion of tert-butyl iodide (C4H9I). Site-selective ionization at the iodine 4d edge with intense femtosecond soft X-ray pulses from an X-ray free-electron laser (XFEL) enables rapid charge buildup and molecular breakup. By correlating ionic fragments in the molecular frame, we isolate complete dissociation channels and reveal subtle structural changes, such as umbrella-type motion of the branched alkyl chain, during the ionization process. Comparison with point-charge simulations of the Coulomb explosion shows close agreement, validating the approach. These results establish covariance/cumulant mapping as a powerful strategy for imaging complex three-dimensional molecular structures and point the way toward time-resolved CEI using both XFEL and tabletop sources for capturing ultrafast structural dynamics.

  PublisherOA PDFDOI

• Fragmentation Dynamics of CS$_2$ Dications and Trications Following S 2p Ionization

  AIP Publishing · 2026-01-01

  otherOpen access

  We present the results from a detailed study of the fragmentation dynamics of CS$_2^{2+}$ and CS$_2^{3+}$, formed in intense femtosecond soft X-ray pulses above the sulfur 2p edge, primarily through single core photoionization from the S 2p site, and subsequent Auger-Meitner decay(s). By combining three-dimensional velocity map imaging with covariance analysis, we determine the relative momenta of the ions produced in each two- and three-body fragmentation channel, at significantly higher ion count rates than conventional coincidence measurements. We shed new light on the wide range of fragmentation channels observed from the CS$_2$ dication and trication, including channels that involve ionization-induced bond formation and fragmentations producing undetected neutral cofragments. In the latter case, a `native frames' approach is used to isolate contributions from concerted and sequential fragmentations and extract dynamical information about each step of a concerted fragmentation process. While dications often fragment sequentially, the trication is dominated by concerted fragmentation. The main trication fragmentation channel into S$^+$+ C$^+$+ S$^+$ can be well-approximated by classical Coulombic simulations of the ground-state geometry distribution, reflecting both the nature of the trication potential energy surface and the rapid multiple ionization prior to substantial structural dynamics. This study demonstrates ways in which fundamental insights into the fragmentation dynamics of polycations following X-ray ionization may be extracted, as will beneficial to future studies that employ time-resolved X-ray Coulomb explosion imaging to study ultrafast photochemistry.

  PublisherDOI

• Supplementary Materials

  AIP Publishing · 2026-01-01

  otherOpen access

  Supplementary Materials

  PublisherDOI

• Supplementary Materials

  AIP Publishing · 2026-01-01

  otherOpen access

  Supplementary Materials

  PublisherDOI

• Ultrafast x-ray scattering of photodissociation dynamics in 2-iodothiophene

  The Journal of Chemical Physics · 2026-01-09 · 1 citations

  articleOpen access

  A time-resolved x-ray scattering (TRXS) investigation of the photodissociation dynamics of gas-phase 2-iodothiophene molecules following 252 nm excitation is presented. Structural evolution of the molecule and dynamical information on the resulting photofragments were captured using femtosecond x-ray free-electron laser pulses. Two dissociation pathways were identified, arising via excitation to ππ* and (n/π)σ* states, respectively, yielding distinct interfragment recoil velocities of ∼6.4 Åps-1 and 17.0 Åps-1. A comparison of asymptotic scattering data with simulated patterns indicates that the thiophene ring remains closed following dissociation at this wavelength. Modeling the experimental data yields a branching ratio of ∼3:1 in favor of the high velocity channel. These findings demonstrate the capability of TRXS to disentangle concurrent ultrafast reaction pathways and provide detailed structural insight into energy redistribution during photoinduced bond fission in complex molecular systems.

  PublisherOA PDFDOI

• Fragmentation dynamics of CS2 dications and trications following S 2p ionization

  The Journal of Chemical Physics · 2026-01-09

  articleOpen access

  We present the results from a detailed study of the fragmentation dynamics of CS22+ and CS23+, formed in intense femtosecond soft x-ray pulses above the sulfur 2p edge, primarily through single core photoionization from the S 2p site, and subsequent Auger-Meitner decay(s). By combining three-dimensional velocity map imaging with covariance analysis, we determine the relative momenta of the ions produced in each two- and three-body fragmentation channel, at significantly higher ion count rates than conventional coincidence measurements. We shed new light on the wide range of fragmentation channels observed from the CS2 dication and trication, including channels that involve ionization-induced bond formation and fragmentations producing undetected neutral cofragments. In the latter case, a "native frames" approach is used to isolate contributions from concerted and sequential fragmentations and extract dynamical information about each step of a concerted fragmentation process. While dications often fragment sequentially, the trication is dominated by concerted fragmentation. The main trication fragmentation channel into S+ + C+ + S+ can be well-approximated by classical Coulombic simulations of the ground-state geometry distribution, reflecting both the nature of the trication potential energy surface and the rapid multiple ionization prior to substantial structural dynamics. This study demonstrates ways in which fundamental insights into the fragmentation dynamics of polycations following x-ray ionization may be extracted, which will be beneficial to future studies that employ time-resolved x-ray Coulomb explosion imaging to study ultrafast photochemistry.

  PublisherOA PDFDOI

• Probing Electronic Coherence between Core-Level Vacancies at Different Atomic Sites

  Physical Review X · 2025-01-16 · 3 citations

  articleOpen access

  The detailed understanding of electronic coherence in quantum systems requires measurements on the attosecond timescale. Attosecond x-ray pulses enable the study of electronic coherence in core-excited molecular systems. Here we report on the coherent motion of electrons in the 1,1-difluoroethylene ion following ionization of the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>K</a:mi></a:math> shell of the two nonequivalent carbon sites with a subfemtosecond x-ray pulse. Using the angular streaking technique to track the Auger-Meitner decay, we observe temporal modulations of the emission, indicating the electronic coherence of the core-excited ionic states, and extract a <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mn>6.5</c:mn><c:mo>±</c:mo><c:mn>0.8</c:mn><c:mtext> </c:mtext><c:mtext> </c:mtext><c:mi>fs</c:mi></c:math> average lifetime of the core-level vacancies. A quantum-mechanical model is employed to interpret the measurement, and we find the observed temporal modulations are independent of charge density oscillations. This work opens a new regime of coherent electronic motion, beyond charge migration, where electronic coherence manifests in the nonlocal quantum correlation between atomic sites while charge density oscillation is absent. Our results broaden the landscape of electronic coherence in molecular systems.

  PublisherDOI

• Time-resolved momentum imaging of UV photodynamics in structural isomers of iodopropane probed by site-selective XUV ionization

  Physical Chemistry Chemical Physics · 2025-01-01

  articleOpen access

  (46), 27338 (2020)], we also model the most likely signatures of this process in the present experiment, and can identify signal in the 2-IP data (that is absent or significantly weaker in the data from the unbranched 1-IP isomer) that is consistent with such a process occurring on ultrafast timescales.

  PublisherOA PDFDOI

• Photon science and quantum control

  Physics Today · 2025-01-01 · 1 citations

  article1st authorCorresponding

  Recent advances in laser technology have hastened developments in other fields—precision measurement, atomic cooling, gravitational-wave sensing, quantum computing, cryptography, and many more. Like the laser itself, those fields may transform society.

  PublisherDOI

Recent grants

• Laser Control of Quantum Evolution in Molecules

  NSF · $1.4M · 2018–2023

• Ultrafast Quantum Control in Molecules

  NSF · $825k · 2015–2019

• Strong Field Quantum Control

  NSF · $1.7M · 2010–2015

• New Directions in Quantum Control

  NSF · $1.5M · 2006–2011

Frequent coauthors

• James Cryan

  SLAC National Accelerator Laboratory

  197 shared

• B. K. McFarland

  153 shared

• P. Krejcik

  SLAC National Accelerator Laboratory

  114 shared

• David A. Reis

  Stanford University

  109 shared

• Ryan Coffee

  SLAC National Accelerator Laboratory

  107 shared

• Adi Natan

  SLAC National Accelerator Laboratory

  106 shared

• Ruaridh Forbes

  Linac Coherent Light Source

  100 shared

• Kelly J. Gaffney

  SLAC National Accelerator Laboratory

  99 shared

Awards & honors

• Norman F. Ramsey Prize of the American Physical Society