This Perspective article considers an experimental system that consists of ultrafast optical, electron, and X-ray time-resolved components. These techniques are used simultaneously on the same sample to study, in real time, the events that occur immediately upon disturbance with an ultrafast optical pulse. Excited states and metastable species are generated on the surface, and the electrical and mechanical waves propagating through the sample are recorded with subpicosecond and sub-Angstrom resolution. The characteristic of each technique is briefly described as a means of introducing the experimental system that intergrates these techniques. The processes evolved after femtosecond excitation of a Au single crystal have been monitored by these techniques. The data presented show changes with a resolution of 0.3 ± 0.1 ps in optical thermoreflectance, 1.0 ± 0.2 ps in electron Bragg diffraction, and 0.6 ± 0.1 ps in X-ray diffraction intensity accompanying shift and broadening.

The mechanism responsible for the redox reaction of [CoIII(en)3]Ac3 to Co(II) complex has been determined to be intramolecular electron transfer. It was measured in real time by means of subpicosecond extended X-ray absorption fine structure spectra, EXAFS, and optical experiments and supported by density functional theory calculations. The proposed mechanism is based on histograms of bond length changes of the transient structures measured as a function of time, with subpicosecond time and sub-Angstrom resolution and femtosecond transient spectra and kinetics after excitation with a 267 nm femtosecond pulse. Even though four Fe and Co complexes were excited in the charge transfer band and the photoinduced redox reaction proceeds with similar high redox quantum yield, the dominant electron operating mechanism differs: intramolecular for amine metal complexes and intermolecular for oxalate metal complexes. The ligand orientation degree of freedom and counterion effect are proposed to provide tentative explanation for the electron transfer mechanism.

We utilize 100 fs optical pulses to induce ultrafast disorder of 35- to 150-nm thick single Au(111) crystals and observe the subsequent structural evolution using 0.6-ps, 8.04-keV X-ray pulses. Monitoring the picosecond time-dependent modulation of the X-ray diffraction intensity, width, and shift, we have measured directly electron/phonon coupling, phonon/lattice interaction, and a histogram of the lattice disorder evolution, such as lattice breath due to a pressure wave propagating at sonic velocity, lattice melting, and recrystallization, including mosaic formation. Results of theoretical simulations agree and support the experimental data of the lattice/liquid phase transition process. These time-resolved X-ray diffraction data provide a detailed description of all the significant processes induced by ultrafast laser pulses impinging on thin metallic single crystals.