About

Mariel Pfeifer is the Principal Investigator of the EQUIP Lab at Cornell University. She holds the position of Assistant Professor in the School of Integrative Plant Science within the Horticulture Section. Her role involves leading research in STEM education to empower students and support instructors and mentors. She is actively involved in mentoring undergraduate and graduate students interested in research positions within her lab. Her work focuses on advancing STEM education through research and mentorship, contributing to the development of effective teaching and learning strategies in the field of plant science.

Research topics

• Materials science
• Optics
• Computer Science
• Composite material
• Nanotechnology
• Chemistry
• Chemical engineering
• Physics
• Crystallography
• Metallurgy
• Organic chemistry
• Chromatography
• Mineralogy

Selected publications

• Optical properties of unoxidized and oxidized titanium nitride thin films

  Journal of Materials Science Materials in Engineering · 2025-01-10 · 5 citations

  articleOpen access

  Abstract This study reports a pulsed laser deposition-assisted synthesis of highly metallic titanium nitride (TiN) and a series of semiconducting titanium oxynitride (TiN x O y ) compounds in thin film form with tunable plasmonic properties by carefully altering the nitrogen (N)-oxygen (O) ratio. The N/O ratio was controlled from 0.3 (highest oxygen doping of TiN) to ~ 1.0 (no oxygen doping of TiN) by growing the TiN films under nitrogen pressures of 50, 35, and 10 mTorr and high vacuum conditions of 2 × 10 −6 Torr with no external gas introduced. The presence of nitrogen in the deposition chamber during the film growth affects the gas phase oxidation of TiN to TiN x O y by increasing the mean free path-dependent N and O inter-collisions per second by two to three orders of magnitudes. The evidence of increased oxidation of TiN to TiN x O y with an increase in nitrogen deposition pressure was obtained using X-ray photoelectron spectroscopy analysis. While the TiN samples deposited in high vacuum conditions had the highest reflectance, TiN x O y thin films were also found to possess high reflectance at low frequency with a well-defined edge around 20,000 cm −1 . Furthermore, the vacuum-deposited TiN samples showed a large negative dielectric constant of -330 and the largest frequency of zero-crossing at 25,000 cm −1 ; the TiN x O y samples deposited in the presence of nitrogen ambient also showed promising plasmonic applications at the near-mid infrared range. A comparison of the dielectric constant and loss function data of this research with the literature values for noble metals seems to indicate that TiN and TiN x O y have the potential to replace gold and silver in the visible and near-infrared spectral regions.

  PublisherOA PDFDOI

• Bulk thermally conductive polyethylene as a thermal interface material

  Materials Horizons · 2025-01-01 · 12 citations

  articleOpen access

  . We utilized wide-angle X-ray scattering to elucidate the molecular structural changes that led to this thermal conductivity enhancement. Furthermore, we conducted a device-cooling experiment and showed a 39% hot spot temperature reduction compared to a commercial ceramic-filled silicone thermal pad under a heating power of 3.6 W. Thus, this bulk-scale thermally conductive PE bar with nanoscale structural refinement demonstrated superior cooling performance, offering potential as an advanced thermal interface material for thermal management in microelectronics.

  PublisherOA PDFDOI

• Author response for "Bulk Thermally Conductive Polyethylene as Thermal Interface Materials"

  2024-12-28

  peer-review
  PublisherDOI

• Modulation of Structural, Electronic, and Optical Properties of Titanium Nitride Thin Films by Regulated In Situ Oxidation

  ACS Applied Materials & Interfaces · 2023 · 31 citations

  • Materials science
  • Chemical engineering
  • Nanotechnology

  energy levels.

  PublisherDOI

• Novel Methods to Detect Trace Quantities of 1-ethyl-3-methylimidazolium tetrafluoroborate

  AIAA SCITECH 2023 Forum · 2023-01-19

  article

  View Video Presentation: https://doi.org/10.2514/6.2023-1410.vid Reliable surface detection of deposited propellant is critical to studying overspray, a primary lifetime limiting mechanism of electrospray thrusters. This work explores four methods for the detection of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4), a room-temperature ionic liquid commonly used as propellant in electrospray thrusters: fluorescent spectroscopy, energy-dispersive X-ray spectroscopy, nonvolatile residue spectroscopy, and Fourier transform infrared spectroscopy. Successful detection of EMI-BF4 deposited onto a gold plated quartz crystal substrate by an electrospray source is demonstrated using energy-dispersive X-ray spectroscopy. Nonvolatile residue spectroscopy is shown to be capable of detecting highly diluted EMI-BF4. Fourier transform infrared spectroscopy was performed on a large drop of EMI-BF4 and differentiation between similar molecules was established. Initial surface contamination studies using UV-Vis fluorescent spectroscopy to detect the presence of EMI-BF4 on quartz crystal substrates are also conducted.

  PublisherDOI

• Forming Anisotropic Crystal Composites: Assessing the Mechanical Translation of Gel Network Anisotropy to Calcite Crystal Form

  Journal of the American Chemical Society · 2021 · 34 citations

  • Composite material
  • Materials science
  • Chemistry

  The promise of crystal composites with direction-specific properties is an attractive prospect for diverse applications; however, synthetic strategies for realizing such composites remain elusive. Here, we demonstrate that anisotropic agarose gel networks can mechanically "mold" calcite crystal growth, yielding anisotropically structured, single-crystal composites. Drying and rehydration of agarose gel films result in the affine deformation of their fibrous networks to yield fiber alignment parallel to the drying plane. Precipitation of calcium carbonate within these anisotropic networks results in the formation of calcite crystal composite disks oriented parallel to the fibers. The morphology of the disks, revealed by nanocomputed tomography imaging, evolves with time and can be described by linear-elastic fracture mechanics theory, which depends on the ratio between the length of the crystal and the elastoadhesive length of the gel. Precipitation of calcite in uniaxially deformed agarose gel cylinders results in the formation of rice-grain-shaped crystals, suggesting the broad applicability of the approach. These results demonstrate how the anisotropy of compliant networks can translate into the desired crystal composite morphologies. This work highlights the important role organic matrices can play in mechanically "molding" biominerals and provides an exciting platform for fabricating crystal composites with direction-specific and emergent functional properties.

  PublisherDOI

• Revealing Three-Dimensional Morphology in Nanoporous Gold Using Three-Dimensional X-Ray Fresnel Coherent Diffractive Imaging Tomography

  Journal of Electrochemical Energy Conversion and Storage · 2020 · 2 citations

  • Computer Science
  • Materials science
  • Optics

  Abstract Nanoporous metals fabricated by dealloying have a unique bi-continuous, sponge-like porous structure with ultra-high surface area. The unique properties of these materials, especially nanoporous gold, have numerous potential applications in sensors and actuators and in energy-related applications such as catalytic materials, super-capacitors, and battery supports. The degree of porosity and size of the metal ligaments are critical parameters that determine many properties and thus govern the functionalities of nanoporous metals in many applications including energy storage and conversion. We used Fresnel coherent diffractive imaging combined with tomographic reconstruction to quantify the nanoscale three-dimensional spatial distribution and homogeneity of the porosity and ligament size within a bulk sample of nanoporous gold. The average porosity and its standard deviation along the axial direction through the sample were determined, as well as the characteristic feature size and its standard deviation. The result shows that free corrosion is an effective way to create homogeneous nanoporous metals with sample sizes on the order of 1 µm.

  PublisherOA PDFDOI

• FlashCam: a fully digital camera for the Cherenkov telescope array medium-sized telescopes

  Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2019-01-01

  article
  Publisher

• FlashCam: a fully-digital camera for the medium-sized telescopes of the Cherenkov Telescope Array

  Proceedings of The 34th International Cosmic Ray Conference — PoS(ICRC2015) · 2016-08-18 · 13 citations

  articleOpen access
  PublisherDOI

• Posthole Broadband Sensor Emplacement vs. Surface Vaults: Observations of Comparative Noise Performance and Trade-offs

  2015 AGU Fall Meeting · 2015-12-16 · 1 citations

  article
  Publisher

Frequent coauthors

• Garth J. Williams

  Brookhaven National Laboratory

  44 shared

• K. Nugent

  Australian National University

  37 shared

• Jesse N. Clark

  35 shared

• Andrew G. Peele

  Australian Synchrotron

  34 shared

• Corey T. Putkunz

  ARC Centre of Excellence in Advanced Molecular Imaging

  27 shared

• Brian Abbey

  La Trobe University

  26 shared

• Ian McNulty

  Wayne State University

  23 shared

• D. J. Vine

  20 shared

Awards & honors

• NSF Graduate Research Fellowship
• ARCS Scholar award