2PPE

Experimental photograph of NCSU’s 2PPE system.  The ultra-high vacuum chamber (right) houses the various samples for material and condensed matter exploration using photoelectron spectroscopy.  Electrons are excited and then ejected by focusing femtosecond laser pulses (purple path highlighted) into the chamber and on the sample surface.  Understanding how the electron energy and momentum evolve as a function of time (top left) is achieved by delaying the time between excitation and photoejection.  – Photograph taken by A. Bataller and D. Nevola in the Gundogdu Laboratory, in partnership with the Dougherty Research Group.  The 2PPE project is supported by the UNC Research Opportunity Initiative within the ORaCEL collaboration.

Dense plasma condensation lies within the cross-section of plasma and condensed matter physics (CMP), and often shares diagnostics from both fields.  A truly powerful method used in CMP and material science is the technique known as two-photon photoelectron spectroscopy (2PPE), also known as time-resolved angle-resolved photoemission spectroscopy (trARPES).  2PPE probes both the energy and momentum of surface electrons in a material, and how they change in time for both valance (ground) and conduction (excited) states.  The wealth of information provided by 2PPE is helping us better understand not only the exotic states of matter found in CMP and dense plasmas, but also the electronic properties of many organic and inorganic semiconductors used for photovoltaics and optoelectronic devices.

Graduate student Dan Nevola and I have successfully built and tested a new 2PPE system in the physics department at NCSU.  We are currently exploring novel material systems and will soon submit our findings.  This unique platform exists at NCSU due to the vision and research partnership known as the Organic and Carbon Electronics Labs (ORaCEL), and is supported by the UNC Research Opportunity Initiative.