The ultrafast motions of atoms during chemical reactions are investigated theoretically and experimentally using x-ray absorption fine structure spectroscopy.
Nano-structured objects are imaged using an imaging modality based on small-angle x-ray scattering. This imaging modality is applied to medical imaging, for instance of liver cancers, as well as the imaging of nanomaterial structures and their chemical or physical transformations. The upconversion of CO2 to feedstock for the chemical industry are studied electro-chemically uning nano-structured electroytes.

Ultrafast chemical dynamics:
A fundamental goal of chemical research has always been to understand the reaction mechanisms leading to specific reaction products. Reaction mechanisms, in turn, are a consequence of the structural dynamics of molecules participating in the chemical process with atomic motions occurring on the ultrafast timescale of femtoseconds (10^-15 s) and picoseconds (10^-12 s). Since these ultrafast motions are the essence of every chemical process, detailed knowledge about their nature is of fundamental importance. Consequently, theoretical modeling and experimental measurement of these ultrafast structural dynamics is of fundamental importance to chemistry and it is our primary area of research.
We use ultrafast x-ray absorption fine structure (UXAFS) measurements of the atomic motions of solvated organometallic complexes during photo-induced ligand substitution reactions. These measurements are accompanied by ultrafast UV transient absorption (UVTA) experiments that measure the reactions times of various reaction paths suggested by our theoretical studies. The UXAFS experiments are carried out in my laboratory using a laser-driven plasma x-ray source as well as at ID7-C at the Advanced Photon Source (Argonne National Laboratory) and at BL6.0.1.2 at the Advance Light Source (Lawrence Berkeley National Laboratory). The UVTA experiments are carried out in my laboratory.

Ultrafast physical dynamics:
The laser-driven plasma x-ray source is used additionally for ultrafast x-ray holographic imaging of picosecond ultrasonic wave packets propagating in the bulk of optically opaque materials. The imaging method relies on x-ray phase contrast imaging, introduced in the next section, and not on x-ray diffraction. The sample material's crystal structure is irrelevant for the imaging process and in the future, materials not accessible to x-ray diffraction will be the major application area.

Bio-medical imaging:
A phase-sensitive x-ray imaging method is applied to biological tissues. This phase-contrast x-ray imaging is fundamentally different from conventional x-ray radiography because the mechanism of image formation does not rely on differential absorption by tissues. Instead, x-ray beams undergo differential phase shifts in passing through an organ and subsequently interfere constructively or destructively at the x-ray camera or film. Hence, tissues are distinguished by their different indices of refraction rather than their absorptive properties. This imaging method is more than a thousand times more sensitive to density variations of tissues than conventional absorption methods and enables imaging of soft tissues with high contrast without the use of contrast agents. We currently apply this modality to the imaging of the micro vascularization of healthy and cancerous murine livers.

Furthermore, our research focuses on the development of an x-ray imaging modality that combines ultrasound-induced motions in tissue with the detection of such motions by phase contrast x-ray imaging. The goal of the research is to lay the foundation for providing, in a single high resolution, high contrast x-ray image, a delineation of differences in tissue elastic properties. The method combines tissue specificity typically exploited in palpation, elastography, and ultrasound imaging, with the high contrast and high resolution of x-ray phase contrast imaging. As a consequence, the modality not just encodes tissue density but also tissue elasticity into the same high-resolution x-ray image, yielding remote palpation with high spatial resolution. The combined information in the x-ray image should greatly aid the detection and characterization of suspicious lesions even in complicated imaging situations such as radiologically dense breast tissue. The image size is only dependent on the size of the x-ray image detector and therefore can be as large as with conventional film systems. Much of this work is carried out in collaboration with Prof. G. Diebold, Dept. of Chemistry, and Prof. J. R. Wands, Alpert Medical School.

1 High-resolution x-ray imaging of tumor angiogenesis," C. Rose-Petruck, Gerald Diebold, J. Wands
"Funding Agency: Brown University
Funding Program: OVR Seed Fund Grant
Funding Period: March 2008 - March 2009"
2 "Ultrafast holographic x-ray imaging and its application to picosecond ultrasonic wave dynamics in bulk materials," C. Rose-Petruck
"Funding Agency: US Department of Energy
Funding Program: Basic Energy Research Program
Funding Period: March 2008 - Feb. 2011"
3 "Ultrafast EXAFS of ligand substitution of transition metal carbonyls" C. Rose-Petruck , B. Adams
"Funding Agency: Advanced Photon Source, ANL, Argonne, IL
Funding Program: User Program
Period: 2009"
4 "Ultrafast Photodissociation and Ligand Exchange in Solvated Transition-metal Carbonyls: Time-resolved EXAFS Studies," C. Rose-Petruck, R. Schoenlein
"Funding Agency: Advanced Light Source, LBNL, Berkely, CA,
Funding Program: User Program
Period: 2009"

"High-resolution angiography: Computed tomography coupled X-ray phase contrast imaging of excised murine liver samples," C. M. Laperle, P. Wintermeyer, E. Walker, D. Shi, M. Anastasio, C. Rose-Petruck, G. Diebold and J. R. Wands, Physics in Medicine and Biology 53, 6911–6923 (2008)

"Structure of solvated Fe(CO)5: Solvation in alcohols," J. Lessing, X. Li, T. Lee and C. Rose-Petruck, J. Phys. Chem. A 112, 2282-2292 (2008)

"Ultrafast x-ray generation from a liquid mercury target," C. Reich, C. M. Laperle, X. Li, B. Ahr, F. Benesch-Lee and C. G. Rose-Petruck, Optics Letters 32 (4), 427 - 429 (2007)

"Propagation based differential phase contrast imaging and tomography of murine tissue with a laser plasma x-ray source," C. M. Laperle, P. Wintermeyer, J. R. Wands, D. Shi, A. A. Mark, X. Li, B. Ahr, G. J. Diebold and C. Rose-Petruck, Applied Physics Letters 91 (17), 173901 (2007)

"X-ray Phase Contrast Imaging: Transmission Functions Separable in Cartesian Coordinates," G. Cao, T. Hamilton, C. Rose-Petruck and G. J. Diebold, J. Am. Optical Soc. A 24, 1201-1208 (2006)

"Ultrafast table-top laser pump - x-ray probe measurement of solvated Fe(CN)64-," T. Lee, Y. Jiang, C. Rose-Petruck and F. Benesch, J. Chem. Phys. 122 (8), 084506/1 - 084506/8 (2005)

"Acoustically Modulated X-ray Phase Contrast Imaging," T. Hamilton, C. J. Bailat, C. Rose-Petruck and G. J. Diebold, Physics in Medicine and Biology 49, 4985-4996 (2004).

"Structure of solvated Fe(CO)5: A concerted XAFS, FTIR, and DFT study of solvation in fluorinated arenes," T. Lee, E. Welch and C. Rose-Petruck, J. Phys. Chem. A 108, 11768-11778 (2004).

"Molecular and compound-specific isotopic characterization of monocarboxylic acids in carbonaceous meteorites," Y. Huang, Y. Wang, M. R. Alexandre, T. Lee, C. Rose-Petruck, M. Fuller and S. Pizzarello, Geochimica et Cosmochimica Acta 69 (4), 1073 - 1084 (2004).

"Acoustic radiation pressure: a "phase contrast" agent for x-ray phase contrast imaging," C. J. Bailat, T. Hamilton, C. Rose-Petruck and G. J. Diebold, Applied Physics Letters 85 (19), 4517-4519 (2004).

"Ultrafast laser-driven x-ray source for x-ray absorption spectroscopy of transition metal complexes," F. Benesch, T. Lee, Y. Jiang and C. Rose-Petruck, Optics Letters 29 (9), 1028-1030 (2003).

"Structure of solvated Fe(CO)5: XANES and EXAFS measurements using ultrafast laser-driven and conventional x-ray sources," T. Lee, F. Benesch, Y. Jiang and C. Rose-Petruck, Chem. Phys. 299 (2-3), 233-245 (2003).

"Structure of solvated Fe(CO)5: FTIR measurements and Density Functional Theory calculations," Y. Jiang, T. Lee and C. Rose-Petruck, J. Phys. Chem. A 107, 7524-7538 (2003).

"Generation of ultrashort hard-x-ray pulses with tabletop laser systems at a 2-kHz repetition rate," Y. Jiang, T. Lee and C. Rose-Petruck, J. Opt. Soc. Am. B 20 (1), 229 - 237 (2003).

"High-average-power 2-kHz laser for generation of ultrashort x-ray pulses," Y. Jiang, T. Lee, W. Li, G. Ketwaroo and C. Rose-Petruck, Opt. Lett. 27 (11), 963 -965 (2002).

"Ultrafast x-ray measurement of laser heating in semiconductors: Parameters determining the melting threshold," A. Cavalleri, C. W. Siders, C. Rose-Petruck, R. Jimenez, C. Toth, J. A. Squier, C. P. J. Barty, K. R. Wilson, K. Sokolowski-Tinten, M. H. von Hoegen and D. von der Linde, Physical Review B 63 (19), 3306 (2001).

"Picosecond-milliangstrom lattice dynamics measured by ultrafast x-ray diffraction," C. Rose-Petruck, R. Jimenez, T. Guo, A. Cavalleri, C. W. Siders, F. Ráksi, J. Squier, B. Walker, K. R. Wilson and C. P. J. Barty, Nature 398, 310-312 (1999).

JILA fellow, 2011

"Imaging with the vibration potential and phase-contrast x-rays," Best Paper of the Year, A. C. Beveridge, C. J. Bailat, T. J. Hamilton, S. Wang, C. Rose-Petruck, V. E. Gusev and G. J. Diebold, SPIE and Fairway-LaserSonix Young Investigator Award, Photonics West Jan 22-27 2005.

"Ultrafast x-ray imaging of molecular dynamics in solution; a research program embedded into an environment that enhances students' learning," C. Rose-Petruck, The National Science Foundation
CAREER Award, Jan. 2000 - Jan. 2004

"Ultrafast x-ray absorption spectroscopy of chemical dynamics: Photolysis and cage recombination of transition metal carbonyls in solution," C. Rose-Petruck, Brown University
Salomon Faculty Research Award, June 1999 - June 2000

"Ultrafast extended x-ray absorption fine structure spectroscopy for measuring molecular dynamics of chemical reactions in solution," C. Rose-Petruck, Research Corporation, Research Innovation Award, May 200"0 - Sept. 2005.

General, introductory Chemistry, Physical Chemistry