James Strohaber, Ph.D.
Assistant Professor of Physics
132 CePAST (Centennial Building)
Tel.: (850) 599-3889
The investigation of the interaction of intense fields and ultrashort pulses of radiation with matter are at the forefront of modern atomic, molecular and optical physics. Our goals in this intensely investigated field of research are facilitated by the use of novel optical techniques and specialized equipment to reveal ultrafast photodynamical processes that have remained conceals from experimental observation. One such process includes the unintuitive process of adiabatic stabilization where an atomic or molecular system stabilizes against ionization when subjected to extreme intensities--in contrast to Fermi’s golden rule.
When laser radiation interacts with a target system, effects such as molecular orientation, carrier envelope phase offsets and spatiotemporal intensity distributions effectively camouflages underlying physical processes because the measured signal are an average of many different process. To render our experiments free of these artefacts, we employ a specialized reflectron-type time-of-flight ion mass spectrometer to circumvent these effects (see figure).
J. Strohaber and C. J. G. J. Uiterwaal, “In situ measurement of three-dimensional ion densities in focused femtosecond pulses,” Phys. Rev. Lett. 100, 023002 (2008), (Editors' Choice, Science 319, 699 (2008)).
J. Strohaber, M. Zhi, A. V. Sokolov, A. A. Kolomenskii, G. G. Paulus, and H. A. Schuessler, “Coherent transfer of optical orbital angular momentum in multi-order Raman sideband generation,” Opt. Letts. 37, 3411 (2012) (cover image).
J. Strohaber, F. Zhu, A. A. Kolomenskii, and H. A. Schuessler, “Observation of anisotropic fragmentation in methane subjected to femtosecond radiation,” Phys. Rev. A 89, 023430 (2014).
Measured distribution of
ions in an xy plane through the focus. Cross sections along the dashed line are shown on the right. The observed nesting of the charge states occurs because the peak intensity is higher at locations closer to the center of the focus.