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  <doc>
    <id>25454</id>
    <completedYear/>
    <publishedYear>2011</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>77</pageFirst>
    <pageLast>96</pageLast>
    <pageNumber/>
    <edition/>
    <issue>Chapter 4</issue>
    <volume/>
    <type>bookpart</type>
    <publisherName>Nova Science Publishers, Inc.</publisherName>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Nanaosecond and femtosecond laser ablation of TeO2 crystals: surface characterization and plasma analysis</title>
    <abstract language="eng">Near-IR femtosecond (fs) (pulse duration = 150 fs, wavelength = 775 nm, repetition 
rate 1 kHz) and VUV nanosecond (ns)  (pulse duration = 20 ns, wavelength = 157 nm, 
repetition rate 1 to 5 Hz) laser pulse ablation of single-crystalline TeO2  (c-TeO2 ) surfaces 
was performed in air using the direct focusing technique. A multi-method 
characterization using optical microscopy, atomic force microscopy and scanning
electron microscopy revealed the surface morphology of the ablated craters. This allowed 
us at each irradiation site to characterize precisely the lateral and vertical dimensions of 
the laser-ablated craters for different laser pulse energies and number of laser pulses per 
spot. Based on the obtained information, we quantitatively determined the ablation
threshold fluence for the fs laser irradiation when different pulse numbers were applied to 
the same spot using two independent extrapolation techniques. We found that in the case 
of NIR fs laser pulse irradiation, the ablation threshold significantly depends on the
number of laser pulses applied to the same spot indicating that incubation effects play an 
important role in this material. In the case of VUV ns laser pulses, the ablation rate is 
significantly higher due to the high  photon energy and the predominantly linear
absorption in the material. These results are discussed on the basis of recent models of the 
interaction of laser pulses with dielectrics. In the second part of this chapter, we use time-
of-flight mass spectrometry (TOFMS) to analyze the elemental composition of the
ablation products generated upon laser irradiation of c-TeO2  with single fs- (pulse
duration ~200  fs, wavelength  398 nm) and ns-pulses (pulse duration 4 ns, wavelength
355 nm). Due to the three order of magnitude different peak intensities of the ns- and fs 
laser pulses, significant differences were observed regarding the laser-induced species in 
the plasma plume. Positive singly, doubly and triply charged Te ions (Te+, Te2+, Te3+) in 
the form of many different isotopes were observed in case of both irradiations. In the case 
of the ns-laser ablation, the TeO+ formation was negligible compared to the fs case and 
there was no Te trimer (Te3+) formation observed. It was found that the amplitude of Te 
ion signals strongly depends on the applied laser pulse  energy. Singly charged oxygen 
ions (O+) are always present as a byproduct in both kinds of laser ablation.</abstract>
    <parentTitle language="eng">Laser-induced plasmas: theory and applications</parentTitle>
    <identifier type="old">28172</identifier>
    <identifier type="isbn">978-1-61324-851-5</identifier>
    <note>Serientitel: Physics Research and Technology – Series title: Physics Research and Technology</note>
    <enrichment key="bibliotheksstandort">Sonderstandort: Publica-Schrank</enrichment>
    <author>S. Beke</author>
    <author>K. Sugioka</author>
    <author>K. Midorikawa</author>
    <author>Jörn Bonse</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Tellurium dioxide crystals</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Femtosecond laser ablation</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>VUV nanosecond laser ablation</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Multiphoton absorption</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Time-of-flight mass spectroscopy</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Incubation</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Optical properties</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Scanning electron microscopy</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Atomic force microscopy</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Isotopes</value>
    </subject>
    <collection role="literaturgattung" number="">Verlagsliteratur</collection>
    <collection role="fulltextaccess" number="">Physisches Exemplar in der Bibliothek der BAM vorhanden ("Hardcopy Access")</collection>
  </doc>
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