An electric-field-resolved non-degenerate four-wave mixing setup for VUV excited molecules

We describe an experimental setup for an electric-field-resolved measurement of the third-order nonlinear optical signal of various samples excited by vacuum-ultraviolet (VUV) pulses. A near-infrared (NIR) femtosecond laser at a central wavelength of 800-nm is used to generate VUV pulses using high harmonic generation (HHG) in Argon. Specially coated mirrors are used to reject NIR and 266-nm (third harmonic of 800 nm) light, while reflecting 160-nm (fifth harmonic) light for the excitation of target gas-phase molecules such as CO­₂, O₂, and C₂H₄, and solid bulk samples such as UVFS, MgO, and ZnO. We utilize a non-degenerate four-wave-mixing scheme involving spatially and temporally overlapped VUV and NIR pulses resulting in a signal at 800-nm. We discuss progress towards completely measuring the electric field to probe ultrafast dynamics in VUV excited molecules.