title: Time-, frequency-, and wavevector-resolved x-ray diffraction from single molecules.
abstract: Using a quantum electrodynamic framework, we calculate the off-resonant scattering of a broadband X-ray pulse from a sample initially prepared in an arbitrary superposition of electronic states. The signal consists of single-particle (incoherent) and two-particle (coherent) contributions that carry different particle form factors that involve different material transitions. Single-molecule experiments involving incoherent scattering are more influenced by inelastic processes compared to bulk measurements. The conditions under which the technique directly measures charge densities (and can be considered as diffraction) as opposed to correlation functions of the charge-density are specified. The results are illustrated with time- and wavevector-resolved signals from a single amino acid molecule (cysteine) following an impulsive excitation by a stimulated X-ray Raman process resonant with the sulfur K-edge. Our theory and simulations can guide future experimental studies on the structures of nano-particles and proteins.
authors.affiliation: University of California, Irvine, California 92697-2025, USA.
authors.forename: Kochise
authors.initials: K
authors.lastname: Bennett
authors.affiliation: University of California, Irvine, California 92697-2025, USA.
authors.forename: Jason D
authors.initials: JD
authors.lastname: Biggs
authors.affiliation: University of California, Irvine, California 92697-2025, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: University of California, Irvine, California 92697-2025, USA.
authors.forename: Konstantin E
authors.initials: KE
authors.lastname: Dorfman
authors.affiliation: University of California, Irvine, California 92697-2025, USA.
authors.forename: Shaul
authors.initials: S
authors.lastname: Mukamel
mesh_terms: D003545:Cysteine / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology; D011506:Proteins / Q000737:chemistry; D011789:Quantum Theory; D013059:Spectrum Analysis, Raman; D014961:X-Ray Diffraction
chemical_list: D011506:Proteins; D003545:Cysteine