Seminar Announcement: Wieslaw Strek

Data pubblicazione: 3-mag-2017 20.45.24

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.