UC Berkeley

Nonlinear spectroscopies employ multiple short coherent pulses to generate higher-order polarization signals. The rich degrees of freedom available for controlling the properties of each beam enable highly selective measurements in both the frequency and time domains. Despite their widespread use with optical pulses, nonlinear spectroscopies have been relatively unexplored in the extreme ultraviolet (XUV) or X-ray spectral regions due to the lack of strong coherent light sources until recently. The objective of this project is to develop nonlinear spectroscopies in these short wavelength regions. A table-top technique, attosecond FWM spectroscopy, has been successfully demonstrated, which utilizes a short attosecond XUV pulse and two noncollinear, few-cycle near-infrared pulses to generate background-free third-order polarization signals. The work detailed in this dissertation has broadened the scope of attosecond FWM spectroscopy and thus has taken the development of nonlinear spectroscopy in the XUV one step further. It includes the successful demonstration of probing ultrafast dynamics in molecules, such as O2 and CO2, and exploring the potential of non-resonant FWM process in a wave packet dynamic in Ar. Looking ahead, the upcoming implementation of attosecond FWM experiments at the carbon K-edge will offer new avenues for investigating chemically and biologically significant organic molecules with nonlinear spectroscopies. Ultimately, attosecond FWM spectroscopy will serve as a solid foundation for future explorations in nonlinear spectroscopy at short wavelength, opening doors to innovative applications in various scientific fields.