Picosecond non-radiative relaxation via internal conversion in Ca10(PO4)F2:Cr

Jon-Paul R. Wells, Thomas P J Han

Research output: Contribution to journalArticlepeer-review


We use a femtosecond pump-probe technique to directly measure fast nonradiative relaxation following excitation of the 3A 23T1 transition in Ca10(PO4)6 F2(CFAP) doped with tetravalent chromium. We measure a 3T1 relaxation time of 137 ps at 10 K which decreases to 37 ps at room temperature through internal conversion directly to the 3A2 ground state. We find rates for quantum mechanical tunnelling and phonon assisted barrier hopping of 0 = 7.9 109 Hz and W1 = 3.4 1011 Hz respectively, with a barrier height of 630 cm-1.
Original languageEnglish
Article number025706
Number of pages6
JournalMaterials Research Express
Issue number2
Publication statusPublished - 7 May 2014


  • calcium compounds
  • chromium
  • ground states
  • high-speed optical techniques
  • hopping conduction
  • phonons
  • tunnelling


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