Valence-to-core (vtc) x-ray emission spectra (XES) provides direct information on occupied valence orbitals and is sensitive to chemical environment. Combining with element specificity and high penetration of hard x-rays, it is emerging as an information-rich technique and its applications have been demonstrated in research fields, such as catalysis and metalloenzymes. However, the vtc feature is typically two orders of magnitude weaker than Kalpha emission lines, making it hard to collect, especially for transient species. To overcome this disadvantage, pink beam excitation capability was demonstrated recently at Sector 7 of the Advanced Photon Source. A water-cooled mirror rejects high harmonics from the undulator, and beryllium compound refractive lenses (CRL) focus the reflected fundamental beam (pink beam) to a 40 x 12 microns elliptical spot (~1e15 photons/second) at the sample target that matches the laser spot size used for photoexcitation. In combination with an ultrafast laser, the focused pink beam was utilized to probe the photoexcited spin crossover (SCO) process of [Fe(II)(bpy)3]2+ in a liquid jet with a laser-pump/x-ray-probe scheme. The results successfully demonstrated the application of this pink beam capability for ultrafast charge transfer dynamics in solvated molecules.

Creator

• Tu, Ming-Feng

DOI

• https://doi.org/10.21985/n2-v486-p058

Subject

• Physics

Language

• en

Alternate Identifier

• etdadmin_upload_662434
• http://dissertations.umi.com/northwestern:14640

Keyword

• laser-pump/x-ray-probe
• compound refractive lenses
• spin crossover
• pink beam
• x-ray emission spectroscopy
• valence to core

Date created

• 2019-01-01

Resource type

• Dissertation

Rights statement

• In Copyright