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Seminar Announcement: Wieslaw Strek

posted May 3, 2017, 1:45 PM by Stefano Varas   [ updated May 3, 2017, 1:45 PM ]

Announcement
Tuesday, 2 May 2017, 11:00
Sala Grande Palazzina B via alla Cascata 56/C

"Laser Induced White Emission in Nanosized Materials"

Wieslaw Strek
Institute of Low Temperature and Structure Research, Polish Academy of Sciences
Wroclaw, Poland
W.Strek@int.pan.wroc.pl

Abstract
Laser induced white emission (LIWE) has been recently reported for a number of nanosized materials, such as: rare earth doped nanocrystalline powders, transparent undoped nanocrystals, and graphene composites. It was shown that LIWE is the broadband anti-Stokes emission characterized by several characteristic features:

  • threshold behavior on excitation density,
  • nonlinear dependence on excitation power P,
  • efficient photocurrent,
  • dependence on atmospheric pressure,
  • dependence on concentration of active ions,
  • dependence on temperature of sample,
  • low temperature of white emission,
  • long rise and decay times.

The examples of LIWE experimental results will be presented. A mechanism leading to white emission will be discussed in terms of avalanche multiphoton ionization and intervalence charge transfer transitions.

Ċ
Stefano Varas,
May 3, 2017, 1:45 PM