Publications and Papers

High-pressure phase of cold-compressed bulk graphite and graphene nanoplatelets (2023)

Collaborators.Ilias Efthimiopoulos, Elissaios Stavrou, Koichiro Umemoto, Sathish Mayanna, Antonius Torode, Jesse S. Smith, Stella Chariton, Vitali B. Prakapenka, Alexander F. Goncharov, and Yuejian Wang

Abstract.We have studied the high-pressure vibrational and structural behavior of bulk graphite and graphene nanoplatelets at room temperature by means of high-pressure Raman spectroscopic and x-ray diffraction probes. We have detected a clear pressure-induced structural transition in both materials, evidenced by the appearance of new Bragg peaks and Raman features, deviating from the starting hexagonal graphitic structure. The high-pressure phase is identified as a partially disordered orthorhombic structure, consisting of mixed sp2- and sp3-type bonding. Our experimental findings serve as direct evidence for the existence of a metastable transient modification in cold compressed carbon, lying between the sp2-type graphite and sp3-type diamond allotropes.

Physical Review B Link

Extracting the Anharmonic Properties of the G-Band in Graphene Nanoplatelets (2020)

Collaborators. Ilias Efthimiopoulos, Sathish Mayanna, Elissaios Stavrou, Antonius Torode, Yuejian Wang

Abstract. We have examined the effect of temperature and pressure on the Raman-active G-band of graphene nanoplatelets with an average thickness of 4 nm. Measuring the Raman mode frequency and width of the G-band as a function of temperature and pressure allowed us to extract the individual factors contributing to the frequency and width of the G-band, that is, the volumetric (thermal expansion) and anharmonic (phonon–phonon interactions) terms responsible for the Raman shift and the electron–phonon coupling and anharmonic contributions controlling the width/lifetime of the G-band. Considering the available literature, the significant role of the anharmonic effects in understanding the G-band physical processes in carbon-based systems is highlighted.

Journal of Physical Chemistry Link

Software Development to Determine the Optimal Parameters of a Tape Transport System (2018)

Collaborators. A. Torode, M. K. Smith, A. Spyrou, C. Harris, S. Lyons, A. C. Dombos, S. N. Liddick

Abstract. To better understand the process of nucleosynthesis in stars today, advanced nuclear physics techniques are needed. At the National Superconducting Cyclotron Laboratory, at Michigan State University, a new tape transport system has been developed for this purpose. Radioactive nuclei can be implanted on the tape system, and after detecting the products of their decay, the tape rotates to remove any remaining unwanted activity. The present work focuses on the development of software to be used for calculating the optimum settings for experiments using the tape transport system.

SJP GINA Paper GNIA Paper (Alternate Format)

A Look at Mathematical Analytic Continuation (2018)

Abstract. Analytic continuation is a tool in which a function can be extended onto a new domain. It is a process that has been used in physics and mathematics for centuries. In this paper, analytic continuation is defined and a few examples of its use are demonstrated. The examples chosen are such that different properties or unique qualities of the analytical continuation technique can be shown. The first example is of an analytical continuation of f(x)=sqrt{x}. The second is a demonstration of determining interesting results using a form of the Riemann Zeta function. Lastly, Euler numbers E_n are defined and expanded upon such that negative and non-integer values of n can be used.

Analytic Continuation Paper

Zeeman Effect on The Hydrogen Atom (2018)

Collaborators. Antonius Torode and Eric Aboud

Abstract. The Zeeman effect comes about from putting an atom in a magnetic field. The magnetic field causes a magnetic moment to be produced and perturbs the energy levels of the atom causing spectral line shifts to appear when modeled or measured with spectroscopy. This was a poster created to demonstrate that effect on the Hydrogen Atom.

Poster

A Review of Quantum Cryptography (2017)

Abstract. Many flaws exist with traditional encryption methods which leave new innovations like quantum cryptography as a subject of high interest. As quantum computing advanced, the security of traditional methods are greater threatened. Quantum cryptography is a method of sending quantum transmissions to create a secure random key shared between two parties so that traditional encryption methods can be utilized effectively. The process utilizes the Robertson uncertainty principle with further advances using quantum entanglement. This process, including flaws and current hacking attempts are discussed in detail.

Quantum Cryptography Paper

Characterizing a Tape Station and Beta Detector For Radioactive Isotope Beam Experiments (2017)

Collaborators. A. Torode, M. K. Smith, F. Naqvi, E. Zganjar, P. deYoung, A. C. Dombos, C. Harris, A. Spyrou

Abstract. In order to better understand the nucleosynthesis of heavy elements, advanced techniques are needed to study decays of neutron-rich nuclei and to constrain astrophysical models. In conjunction with the Summing NaI(Tl) detector (SuN) at the NSCL, a tape station is being developed to optimize these measurements. A radioactive isotope beam will be implanted directly onto metallic tape at the center of SuN. The primary ions will beta-decay toward stability, however radiation from the daughter nuclei presents a significant source of contamination. The tape rotates so that the implantation point moves into a shielded box outside of SuN to remove the contamination after a certain time. The timing depends on the half-life of the primary and daughter ions so a simulation was developed to determine effective timing parameters to use in each experiment. A new plastic scintillator will be used in conjunction with the tape to detect beta particles. Light from the plastic will be collected with wavelength shifting fibers that will be coupled to photomultiplier tubes outside of SuN. The status of the tape station, including the simulation and characterizing of the fiber detector will be discussed.

DNP/APS Conference Poster

Exploration of the Quantum Casimir Effect (2017)

Abstract. Named after the Dutch Physicist Hendrik Casimir, The Casimir effect is a physical force that arises from fluctuations in electromagnetic field and explained by quantum field theory. The typical example of this is an apparent attraction created between two very closely placed parallel plates within a vacuum. Due to the nature of the vacuum’s quantized field having to do with virtual particles, a force becomes present in the system. This effect creates ideas and explanations for subjects such as zero-point energy and relativistic Van der Waals forces. In this paper I will explore the Casimir effect and some of the astonishing mathematical results that originally come about from quantum field theory that explain it along side an approach that does not reference the zero-point energy from quantum field theory.

Casimir Paper Casimir Poster Casimir Paper (Alternate Format)

Superfluidity for Liquid Helium and Experimental Sound Speed Results below the lambda-Point (2017)

Collaborators. Antonius Torode, Jane Kim

Abstract. In this work, we cool liquid helium to a superfluid phase to measure its properties. We produced the correct conditions such that second sound waves are generated through liquid Helium-4. We record peak amplitudes and use them to calculate speeds of sound through the liquid helium in its superfluid phase. We used a method of determining the speeds through a medium, which prove to give consistent results at room temperatures. As cooled, systematic errors arose through a 120 Hz noise in low frequency ranges. Unknowingly, we collected a large amount of data on this noise which lead to odd results until eventually using those results to confirm which resonant peaks in a data set are actually due to second sound. We are able to reproduce similar results for second sound speeds at varying temperatures when comparing to published literature results.

Superfluidity Paper

A Brief Review of Electromagnetic Scattering Properties and Interactions With Carbon Nanotubes (2017)

Abstract. Electromagnetic radiation is a key concept in understanding modern technology and properties of interactions between various matter. The current models and developments of scattering effects against Carbon nanotubes are examined and discussed. A variety of the current modeling techniques are mentioned including method of moment analysis and recursive methods along with examples of the data and conclusions collected from multiple research teams. This leads to some possible implications and applications which are briefly mentioned and discussed such as electromagnetic shielding and possible manipulation of scattering wave patterns.

EM Scattering Paper

A Brief Review of Nuclear Pasta Models and Theoretical Predictions (2017)

Abstract. Background: Nuclear Pasta, which is named after it's structure, is a model that describes various structures of matter in very high density situations such as that of a neutron star. Method: Through simulations using algorithms such as minimum spanning trees, which determine how nuclei interact with those around it, we can model the structure that matter may take in neutron stars. Through these simulations, we can gain an understanding of the behavior that nuclear matter exhibits under specific conditions. These simulations take massive amounts of computational power and time to run but the results allow us to see the changes that density and other parameters have on matter formation. Results: These simulated structures (see figures in text) are referred to as nuclear pasta due to the pasta like structures that matter forms which resemble that of lasagna, spaghetti, gnocchi and others. Conclusion: Through the nuclear pasta simulations, we can determine that density has a high affect on the nuclear structure and that both coulomb attraction and short range nuclear interactions play a pivotal role in high density nuclear structures.

Nuclear Pasta Paper

Miscellaneous Projects