Jordan Gerton - Academia.edu (original) (raw)

Papers by Jordan Gerton

arXiv (Cornell University), Feb 1, 2023

Physical Review Physics Education Research

In 2017 the University of Utah experienced a tragedy which catalyzed already active changes in th... more In 2017 the University of Utah experienced a tragedy which catalyzed already active changes in the department. In the aftermath, admissions to the graduate program was paused while new policies were developed and implemented. This article outlines this change process through the perspectives and accounts of those involved. Through in-depth interviews with students, staff, faculty, and administrators the process of change was found to be a complex path that involved robust practices of gathering input. This input was considered by a centralized group (the executive committee) advising the department chair and administrators. Findings indicated that the collective desire to reopen the program inspired most faculty to work together to find solutions, while some stakeholders did not fully buy in to large-scale programmatic changes. Further, interviews revealed the persistence of deep cultural challenges after the development and implementation of new policies. A new metaphor for this change is suggested to be a bonfire, as a tragedy sparked the fire of change structures which had already been built, and continual fuel is needed to sustain these changes. Moving forward the department is extending their graduate reform into undergraduate initiatives and normalizing evidencebased teaching practices. Content warning: This paper discusses the death by suicide of a graduate student.

Microscopy and Microanalysis

This document provides supplementary information to "Spectral Signatures of Transverse Optical Mo... more This document provides supplementary information to "Spectral Signatures of Transverse Optical Modes in Semiconductor Nanowires,"

Technical Digest. Summaries of Papers Presented at the International Quantum Electronics Conference. Conference Edition. 1998 Technical Digest Series, Vol.7 (IEEE Cat. No.98CH36236)

Summary form only given. A technique based on coherent Fourier optical imaging is proposed to det... more Summary form only given. A technique based on coherent Fourier optical imaging is proposed to detect an atomic superfluid state in a degenerate gas of 6Li atoms. We show that the superfluid state is characterized by the formation of atomic Cooper pairs in the degenerate 6Li gas. The key to observe such a superfluid state is to determine the quantum

Undergraduate Research Abstracts Journal, 2006

Bulletin of the American Physical Society, 2017

provide precious clues about the formation of planets in the solar system. In particular, carbona... more provide precious clues about the formation of planets in the solar system. In particular, carbonaceous chondritic meteorites, considered the most primitive surviving materials from the early Solar System, can contribute to understand how planetisimals (the precursors to planets, of 1-100 km in radius) formed from dust (micron-size grains). These relics are mainly composed of chondrules (micro/millimeter-sized inclusions) surrounded by a matrix of microparticles. Here we present a comparative study of the structure and composition of the chondrules and surrounding matrix of different carbonaceous chondritic meteorites using low-and high-resolution micro-Raman spectroscopy and SEM/EDS (Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy). We examine how these properties vary in different regions of the chondrules and matrix, capturing details from micrometer to millimeter scales. We compare the structure and composition between different samples, looking for signatures of the physical processes that drove their formation.

2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC), 2018

We discuss the optoelectronic property variation between grains and grain boundaries of CdTe poly... more We discuss the optoelectronic property variation between grains and grain boundaries of CdTe polycrystalline thin films using a confocal microscopy system. Single-photon photoluminescence (PL) and time-resolved photoluminescence spectroscopy (PL) is used to map 10times10mumathrmm210 \times 10 \mu \mathrm {m}^{2}10times10mumathrmm2 area at the back surface of CdTe with an optical resolution of 104 nm. TRPL maps show that different grain boundaries have different near-surface lifetimes. Surprisingly, grain-boundaries with high near-surface lifetime are associated with regions of the sample that have low PL yield. This study demonstrates the potential of confocal PL and TRPL mapping to understand carrier lifetime variations in thin films.

Microscopy and Microanalysis, 2021

Point Spread Function (PSF) engineering is a branch of Localization Microscopy (LM) that can impr... more Point Spread Function (PSF) engineering is a branch of Localization Microscopy (LM) that can improve localization precision and allow identification of multiple spectral channels without using traditional emission filters or spectrometers.

Optica, 2021

In order to build nanophotonic devices, it is important to understand and ultimately control the ... more In order to build nanophotonic devices, it is important to understand and ultimately control the optical mode structure within potential components such as nanoscale waveguides. However, experimental characterization of such modes in the optical regime is difficult due to the nanoscale dimensions of such components and the perturbations that would be induced by a near-field probe. Here, we demonstrate a probe-free, far-field method to characterize the optical modes within GaN nanowires (NWs) based on a novel off-axis scanning confocal microscope system. Using this microscope, we observe spectral signatures resulting from lateral leakage of waveguide modes when they exceed their respective cutoff limits. We identify these modes within hyperspectral images using an analytical model coupled with finite element simulations. The model can also be used to predict the spectral signatures for given geometrical and dielectric parameters, which enabled us to deduce the transverse dimension of...

Microscopy and Microanalysis, 2019

Microscopy and Microanalysis, 2018

Journal of Materials Research, 2017

<jats:title>Abstract</jats:title> <jats:p> <jats:fig position="anchor&q... more <jats:title>Abstract</jats:title> <jats:p> <jats:fig position="anchor"> <jats:graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="jpeg" mimetype="image" position="float" xlink:href="S0884291417003612_figAb" xlink:type="simple" /> </jats:fig> </jats:p>

Nature, 2000

The dynamical behavior of Bose-Einstein condensation (BEC) in a gas with attractive interactions ... more The dynamical behavior of Bose-Einstein condensation (BEC) in a gas with attractive interactions is striking. Quantum theory predicts that BEC of a spatially homogeneous gas with attractive interactions is precluded by a conventional phase transition into either a liquid or solid 1. When confined to a trap, however, such a condensate can form 2 provided that its occupation number does not exceed a limiting value 3,4. The stability limit is determined by a balance between self-attraction and a repulsion arising from position-momentum uncertainty under conditions of spatial confinement. Near the stability limit, self-attraction can overwhelm the repulsion, causing the condensate to collapse 5-8. Growth of the condensate, therefore, is punctuated by intermittent collapses 9,10 , which are triggered either by macroscopic quantum tunneling or thermal fluctuation. Previous observation of growth and collapse has been hampered by the stochastic nature of these mechanisms. Here we reduce the stochasticity by controlling the initial number of condensate atoms using a two-photon transition to a diatomic molecular state. This enables us to obtain the first direct observation of the growth of a condensate with attractive interactions and its subsequent collapse. Condensate growth is initiated by cooling the gas below the critical temperature T c for BEC. For attractive interactions, the number of condensate atoms N 0 grows until the condensate collapses. During the collapse, the density rises giving a sharp increase in the rate of collisions, both elastic and inelastic. These collisions cause atoms to be ejected from the condensate in an energetic explosion. The physics which determines both the stability condition and the dynamical process of collapse of the condensate, draws some interesting comparisons to a star going supernova 11 , even though the time, length, and energy scales for these two phenomena are vastly different. In the stellar case, the stability criterion is provided by a balance between the pressure due to the quantum degeneracy of electrons which make up the star and gravitational attraction. If the mass of the star exceeds the stability limit 12 , the star collapses, releasing nuclear energy and triggering a violent explosion. In contrast to the stellar

Spectroscopy Letters, 2017

ABSTRACT Meteorites provide precious clues about the formation of planets in the solar system. He... more ABSTRACT Meteorites provide precious clues about the formation of planets in the solar system. Here, an analytical method to study chondritic meteorites using low- and high-resolution micro-Raman spectroscopy is presented. An approach in mapping the distribution of mineral compositions of a sample is introduced by measuring ∼104 Raman spectra along linear, micron-wide paths that traverse the sample to capture detail on small and large spatial scales (from micrometers to millimeters). To refine these analytical procedures, a well-defined chondrule and surrounding matrix of the carbonaceous chondrite Northwest Africa 3118 are analyzed. The morphology and elemental composition of the sample are also studied using scanning electron microscopy with energy-dispersive X-ray spectroscopy and creating composite maps with the images obtained by these techniques along the same Raman linear path. The Raman line scan maps of this sample show clear spatial segregation of constituents including pyroxene and olivine, both within and outside the chondrule. Graphitic carbon is also present and appears clustered in domains of a few hundred microns both in the matrix and in the central core of the chondrule. The results obtained with the scanning electron microscopy and energy-dispersive X-ray spectroscopy techniques show that iron is most abundant in the matrix surrounding the chondrule, while the chondrule is enhanced in silicon, magnesium, calcium, aluminum, and sodium. These findings provide a detailed identification of the elemental and mineralogical, spatial composition of the analyzed regions of Northwest Africa 3118.

Aps Four Corners Section Meeting Abstracts, Oct 1, 2006

Biological cells fabricate and assemble molecular building blocks into diverse molecular networks... more Biological cells fabricate and assemble molecular building blocks into diverse molecular networks with striking complexity and functionality. As such, they are model integrated nanosystems whose study should yield important information for optimizing specific cellular functions, and for engineering functional synthetic nano-systems. To study biological systems in this context, it is crucial to observe their molecular machinery at work in a physiologically relevant environment. Currently, there are no techniques that can accomplish this.To study these systems at the molecular length scale, we have developed a near-field microscopy technique called tip-enhanced fluorescence microscopy (TEFM) that combines tapping-mode atomic force microscopy (AFM) with confocal fluorescence microscopy. Briefly, a strong axial field is produced at the focus of a laser beam and an AFM probe is positioned into the focus. This creates a localized dipole field at the tip apex, which can strongly excite fluorescence of nearby chromophores. Scanning the illuminated tip over a surface leads to high-fidelity fluorescence images with resolution limited only by the sharpness of the tip. In contrast to AFM, TEFM also provides single-molecule sensitivity and biochemical specificity when combined with fluorescence labeling. We recently demonstrated ∼10 nm resolution in TEFM images of quantum dots in air and we are now working to extend its capabilities to liquid imaging and to improve the resolution yet further by attaching carbon nanotubes to the ends of the AFM tips.

International Quantum Electronics Conference, May 8, 1998

A Bose-Einstein condensate composed of trapped atoms with negative scattering length exhibits rem... more A Bose-Einstein condensate composed of trapped atoms with negative scattering length exhibits remarkable dynamical behavior. The attractive mean-field interaction makes the condensate unstable when its occupation number is too large, causing it to implode; for ^7Li in our magnetic trap, the stability limit is about 1200 atoms.(C.C. Bradley et al.) Phys. Rev. Lett. 78, 985 (1997) When a collapse occurs,