Photoluminescence in rayirradiated quartz investigated by synchrotron radiation

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Photoluminescence in ?-ray-irradiated ?-quartz
investigated by synchrotron radiation
M. Cannas , S. Agnello, R. Boscaino, F.M.
Gelardi, INFM and Dipartimento di Scienze
Fisiche ed Astronomiche, Palermo, Italy. A.
Trukhin, Institute of Solid State Physics,
University of Latvia, Kengaraga iela 8, LV-1063
Riga, Latvia
5th European Conference on Luminescent Detectors
and Transformers of Ionizing Radiation September
1-5, 2003 Prague, Czech Republic
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Outline

• Introduction
• Optical properties of defects in amorphous
  and crystalline SiO2

• Samples and Methods

• Results
• Luminescence features temperature dependence
  and time decay

• Discussion
• Comparison with previous results in silica

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0ptical bands in crystalline- and amorphous- SiO2

• Optical properties associated with defects in
  the different forms of SiO2 are investigated
  since ?40 years.

Similarities between optical bands in ?-quartz
and silica are limited to few observations.
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In this work, we deal with luminescence related
aspects not yet investigated aiming to clarify
the processes following the 7.6 eV excitation in
crystalline SiO2
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Experimental Methods

• Sample ?-irradiated a-quartz (?-dose 1 Grad)

• Experiments

i) Optical Absorption (OA) by a spectrometer
(ACTON SP 150) fluxed with nitrogen gas (300 K)
equipment in Palermo.
ii) Photoluminescence (PL) Emission and
excitation spectra, Lifetime measurements (17.5
to 300 K) by Synchrotron Radiation (SR) source at
DESY (Hamburg)
SR provides intense and broad spectral emission
over the UV and vacuum-UV range lifetime PL
measurements with resolution less than 10-9 s.
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Resultsoptical bands
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Results temperature dependence

• UV band quenching above 40 K

• Blue band initial increase and quenching above
  100 K

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Results kinetic features
Best-fitting APL? exp(-t/t)
UV band t 1.0 ns
Blue band t 3.6 ns
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DiscussionFeatures of UV and Blue band
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Discussioncomparison with silica
Silica conversion process between two distinct
variants of ODC Experiments JPCM, (1999) PRB
(2003) Nishikawa et al. PRL (1994) Skuja, JNCS
(1998) Computations Uchino et al. PRL (2001)
Donadio et al. PRL (2001).
PL at 4.9 eV in ?-quartz could be the counterpart
of the PL at 4.4 eV in silica
PL at 2.7 eV in ?-quartz could not be related to
the PL at 2.7 eV in silica, because of the
different lifetime
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Conclusions

• We have investigated the photoluminescence
  associated with defects induced in crystalline
  ?-quartz by 1 Grad ?-dose
• Excitation by synchrotron radiation within the
  absorption band at 7.6 eV produces two emissions,
  observable only at low temperature
• 4.9 eV (UV band), lifetime of 1 ns, which
  quenches above 40 K
• 2.7 eV (Blue band), lifetime of 3.6 ns, quenching
  above 100 K
• In analogy with silica glass, the UV emission
  could be related to the conversion between
  different variants of oxygen deficient centers
  occurring upon 7.6 eV excitation, whereas the
  blue band, because of its kinetic features, seems
  to be peculiar of the ?-quartz.