Free-electron laser wavelength-selective materials alteration and photoexcitation spectroscopy

The free-electron laser (FEL) has become an important tool for producing high-intensity photon beams, especially in the infrared. Synchrotron radiationʹs primary spectral domains are in the ultraviolet and X-ray region. FELʹs are therefore excellent complimentary facilities to synchrotron radiation sources. While FELʹs have seen only limited use in experimentation, recently developed programs at Vanderbilt University in Nashville, TN, are swiftly rectifying this situation. This review paper examines practical experience obtained through pioneering programs using the Vanderbilt FEL, which currently hosts one of the largest FEL materials research programs. Results will be discussed in three areas: two-photon absorption in germanium, FEL-assisted internal photoemission measurements of interface energy barriers (FELIPE), and wavelength-specific laser diamond ablation.