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UID:UW-Physics-Event-8794
DTSTART:20240826T150000Z
DTEND:20240826T170000Z
DTSTAMP:20260413T204126Z
LAST-MODIFIED:20240607T172717Z
LOCATION:B343 Sterling Hall\; https://uwmadison.zoom.us/j/93280743741?
 pwd=dWNwMUk4ZjZ6V3Z6V2lDdE1XVWJMZz09#success
SUMMARY:Nonlinear X-ray Optics for Transition Metal Chemistry and Cohe
 rent X-ray Spectroscopy\, Preliminary Exam\, Zain Abhari\, Physics PhD
  Graduate Student
DESCRIPTION:My thesis work encompasses two main projects: building and
  commissioning an XUV femtosecond transient absorption spectroscopy ta
 bletop instrument and designing new nonlinear spectroscopy and imaging
  techniques in the hard X-ray domain utilizing stimulated X-ray emissi
 on.<br>\n<br>\nAdvancements in tabletop XUV sources driven by high har
 monic generation have enabled ultrafast\, element-specific measurement
 s outside large-scale X-ray free electron laser facilities. Despite th
 eir potential\, these sources were previously limited to academic labs
  specializing in nonlinear optics and ultrafast laser systems. To incr
 ease access across other scientific disciplines\, we established an XU
 V femtosecond absorption spectroscopy tabletop (XFAST) instrument at t
 he University of Wisconsin – Madison as a national user facility. My
  contributions included constructing the vacuum system and configuring
  the optical pump line. In addition to being the instrumentation consu
 ltant for XFAST\, I have a focus in designing nonlinear hard X-ray spe
 ctroscopy techniques and new X-ray sources.<br>\n<br>\nFurthering our 
 understanding of electron dynamics and obtaining structural informatio
 n from materials necessitates ultrashort X-ray pulses on femtosecond o
 r attosecond timescales. We pursue two methods to achieve intense\, ul
 trafast X-ray pulses: stimulated emission for femtosecond coherent har
 d X-ray pulse pairs\, and superradiance for hard X-ray attosecond spik
 es. Recently\, we designed and demonstrated a femtosecond X-ray pulse 
 pair spectrometer using stimulated emission\, encoding ultrafast dynam
 ics information in CCD image contrast. Superradiance\, if observed in 
 the hard X-ray regime\, could offer powerful imaging capabilities\, al
 though distinguishing it from stimulated emission presents challenges.
  Our designed experiments aim to confirm superradiance's observation s
 eparately from stimulated emission.
URL:https://www.physics.wisc.edu/events/?id=8794
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