Daniel Sneed

 

Status: Ph. D. Physics, 2nd yearDanielSneed_2015SSAPposteraward

Project: Exploring the high pressure – high temperature electronic and structural behavior in heavy metal nitrides and oxides using in situ direct CO2 laser heating with X-ray Absorption Spectroscopy

Advisor: Dr. Ashkan Salamat

email address: sneedd3@unlv.nevada.edu

 

Education:

  • M.Sc. Physics

University of Nevada, Las Vegas, 2016

  • B.S. Physics

University of Nevada, Las Vegas, 2014

  • A.A.S Network Engineering

Great Basin College, 2010

 

Research:

Many materials have been predicted to show extraordinary electronic behavior under high-pressure and high-temperature conditions. For example, many heavy metal nitrides and oxides have been predicted to show a broadening of their band gap with pressure, contrary to the standard band gap closure. X-ray Absorption Spectroscopy (XAS) is a very powerful technique for probing both electrical and structural properties of materials. My current research involves investigating the predicted electronic and structural behavior of many heavy metal nitrides and oxides by combining CO2 laser heating with ultra high pressure XAS.

Using a CO2 laser is very advantageous over traditional laser heating when working with wide band gap materials such as heavy metal nitrides and oxides. CO2 lasers operate in the mid IR regime (~10 μm), which is on the order of the wavelength of lattice vibrations in many materials; this allows the heating through phonon excitation. Because of this, wide band gap materials can be directly heated using a CO2 laser. Also, typical XAS experiments utilize beryllium as a gasket material, due to its low Z. Like most metals, beryllium has a very high reflectance in the mid-IR regime, preventing any coupling with the laser, and therefore a CO2 laser will not heat the beryllium at these power densities. Since the CO2 laser will not interact with the beryllium, CO2 heating removes the dangers of heating and damaging the beryllium.

 

National Laboratories:

Type of experiments conducted and the labs used:

  • Conducted Angular Dispersive X-ray Diffraction experiments at Argonne National Lab Advanced Photon Source
  • Conducted Energy Dispersive X-ray Diffraction experiments at Argonne National Lab Advanced Photon Source
  • Conducted Resonant X-ray Inelastic Scattering experiments at Argonne national Lab Advanced Photon Source
  • Conducted X-ray Absorption Spectroscopy experiments at Argonne National Lab Advanced Photon Source
  • Conduced on line and off line Raman Spectroscopy Experiments at Argonne National Lab Advanced Photon Source
  • Conducted Raman Experiments in the High Pressure Science and Engineering Center at UNLV
  • Conduced MidIR experiments at the Canadian Light Source
  • Conducted FarIR experiments at the Canadian Light Source
  • Conduced X-ray Absorption Spectroscopy experiments at the Canadian Light Source

 

Internship experiences:

  • 2015 Summer internship at Lawrence Livermore National Laboratory under Dr. Natalia Zaitseva

 

Collaborations with national lab scientists:

  • Collaboration with Dr. Changyong Park from Argonne National Laboratory Advanced Photon Source
  • Collaboration with Dr. Ning Chen from the Canadian Light Source
  • Collaboration of Dr. Brant Billinghurst from the Canadian Light Source

 

Professional schools & workshops:

  • 2013 NSSC Nuclear Policy Summer School
  • 2015 NSSC-LANL Nuclear Safeguards and Securities summer School
  • 2015 Summer Under Pressure School at the Joint AIRAPT-25 & EHPRG-53 conference in Madrid, Spain

 

Awards:

  • 2015 NSSC MSI Summer Research Fellowship
  • 2014 SSAA Annual Review conference Outstanding Poster Award
  • 2015 SSAA Annual Review conference Outstanding Poster Award
  • 2017 SSAA Annual Review conference Outstanding Poster Award
  • Student travel scholarship for 2013 APS-SCCM & AIRAPT -24 Joint Conference in Seattle, WA
  • Student travel scholarship for 2015 Joint AIRAPT-25 & EHPRG-53 conference in Madrid, Spain
  • Donna Weistrop and David B. Schaffer Scholarship 2016
  • Featured in 2016 Stewardship Science Academic Programs Annual pg. 24

 

Publications:

  1. “Measurement of the Energy Dependence of X-ray Induced Decomposition of Potassium Chlorate,” M. Pravica, D. Sneed, L. Bai, C. Park, Journal of Applied Crystallography (2013).

 

  1. “High pressure X-ray photochemical studies of carbon tetrachloride: Cl2 production and segregation,” M. Pravica, D. Sneed, Q. Smith, and L. Bai, Chemical Physics Letters, Volume 590, 74-76, (2013).

 

  1. “X-ray induced mobility of molecular oxygen at extreme conditions,” Michael Pravica, D. Popov, S. Sinogeikin, D. Sneed, G. Guardala, and Q. Smith, Applied Physics Letters (2013).

 

  1. “Carbon tetrachloride at extreme conditions,” M. Pravica, D. Sneed, Y. Wang, Q. Smith, and G. Subrahmanyam, Journal of Chemical Physics, 140, 194503 (2014)

 

  1. “Effect of Pressure and Temperature on Structural Stability of MoS2”, N. Bandaru, R. Kumar, D. Sneed, O. Tschauner, J. Baker, D. Antonio, S. Luo, T. Hartmann , Y. Zhao, and R. Venkat, Journal of Physical Chemistry C, 118 (6), 3230–3235 (2014).

 

  1. “Communication: A novel method for generating molecular mixtures at extreme conditions: The case of hydrogen and oxygen,” M. Pravica, D. Sneed, M. White, and Y. Wang, The Journal of Chemical Physics, 141, 091101 (2014)

 

  1. “Note: Loading method of molecular fluorine using x-ray induced chemistry”, M. Pravica, D. Sneed, M. White, Y. Wang, Review of Scientific Instruments, 85, 086110, (2014)

 

  1. “Studies in useful hard x-ray photochemistry: decomposition of potassium halates”, M. Pravica, B. Hulsey, L. Bai, D. Sneed, Q. Smith, F. Guardala, Journal of Physics: Conference Series, Vol 500, 2, 022009, (2014).

 

  1. “Pressure induced structural transitions in CuSbS2 and CuSbSe2 thermoelectric compounds,” J Baker, R Kumar, D Sneed, A Connolly, Y Zhang, N Velisavljevic, J Paladugu, M Pravica, C Chen, A Cornelius, Y Zhao, Journal of Alloys and Compounds, Volume 643,186-194, (2015).

 

  1. “Hexafluorobenzene under Extreme Conditions”, M. Pravica, D. Sneed, Y. Wang, Q. Smith, and M. White, The Journal of Physical Chemistry B, 120 (10), 2854-2858, (2016)

 

  1. “A Novel Synthesis of Polymeric CO via Useful Hard X-ray Photochemistry” M. Pravica, D. Sneed, Q. Smith, B. Billinghurst, T. May, M. White, K. Dziubek, and R. Ahuja, Cogent Physics, Vol. 3, Issue 1, (2016)

 

  1. “Forcing Cesium into Higher Oxidation States via Useful Hard X-ray Induced Chemistry at Extreme Conditions”. D. Sneed, UNLV Theses, Dissertations, Professional Papers, and Capstones. 2807, (2016).

 

  1. “Forcing Cesium into Higher Oxidation States Using Useful hard x-ray Induced Chemistry under High Pressure,” D Sneed, M Pravica, E Kim, N Chen, C Park, M White, Journal of Physics: Conference Series, accepted for publication, 31 December, 2016.

 

  1. “High Pressure Studies of Potassium Perchlorate”, M. Pravica, Y. Wang, D. Sneed, S. Reiser, M. White, Chemical Physics Letters, Vol. 660, 37-42, (2016).

 

  1. “Inner-shell chemistry under high pressure”, M. Miao, J. Botana, M. Pravica, D. Sneed, C. Park, Japanese Journal of Applied Physics, Vol 56, 5S3, (2017)

 

Presentations:

  1. Poster presentation at 2012 HPCAT Workshop
  2. Poster presentation at 2013 APS-SCCM & AIRAPT -24 Joint Conference in Seattle, WA
  3. Poster presentation at 2014 SSAA annual review conference
  4. Poster presentation at 2015 SSAA annual review conference
  5. Poster presentation at 2015 LANL-NSSC Nuclear Safeguards and Security Summer     School
  6. Accepted talk 2015 Joint AIRAPT-25 & EHPRG-53 conference in Madrid, Spain
  7. Poster Presentation at 2016 SSAA annual review conference
  8. Poster presentation at 2017 SSAA annual review conference

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