Time-Resolved Attosecond Spectroscopy of He Using COLTRIMS

Abstract: Tunable ultrafast lasers are becoming a standard tool for probing and controlling the dynamics of atoms, molecules and chemical reactions. This thesis is a contribution to a large, ongoing effort to make spectroscopic tools for inducing and controlling, in real time, the natural processes which occur on the femto and attosecond times scales.Femtosecond lasers, with a fundamental wavelength in the infrared (IR) spectral region, can be used for producing a fascinating spectroscopic tool - extreme ultraviolet (XUV) pulses with typical duration of hundreds of attoseconds. A typical XUV attosecond pulse is produced when an intense ultrafast laser is focused in a gaseous target. The fundamental laser frequency gets upconverted into its higher harmonics through an extreme nonlinear process in which the electron leaves the ion's potential well and oscillates in the laser field emitting a short burst of radiation every time it is driven back into the vicinity of its parent ion by the linearly polarized laser electric field. In this thesis, we present several examples of using IR and XUV pulses to induce and control the excitation and ionization processes in atoms and molecules on the attosecond time scale. A 3D momentum imaging technique called COLTRIMS is used to collect all the reaction products (electrons and ions) in coincidence.The experiments were performed at the J.R.M. lab at the Kansas State University, where the experimental apparatus was designed and built under the supervision of professor C.L. Cocke.