Papers by Prabhakar Misra
Universe
Radio emission has been detected for all types of stars in the Hertzsprung Russell diagram. Large... more Radio emission has been detected for all types of stars in the Hertzsprung Russell diagram. Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) low and medium-resolution spectroscopic surveys provide a good opportunity to obtain the spectroscopic properties of radio stars. We cross-matched big data from the LAMOST DR7 low resolution spectral survey with a catalogue of radio stars, and obtained 449 stellar spectra of 258 stars. We detected 185 spectra with Hα emission. There are a total of 108 objects with repeated low resolution spectral observations, of which 63 show variations in the Hα line over a long time, about several months. We cross-matched LAMOST DR7 medium resolution spectra with the radio star catalogue. We obtained 1319 LAMOST medium-resolution spectra of the 156 radio stars and then calculated their equivalent widths (EWs) of the Hα line. Among them, 93 radio stars with Hα emission were found from the LAMOST medium resolution spectra, and 63 objects show...
AGU Fall Meeting Abstracts, Dec 1, 2019
Address of Misra, Ferguson and Rao: Department of Physics. The Ohio State University, Columbus, O... more Address of Misra, Ferguson and Rao: Department of Physics. The Ohio State University, Columbus, Ohio, 43210. Address of Mathews: Department of Chemistry, The Ohio State University, Columbus, Ohio, 43210.
$^{a}$ Financial support from the NASA Lewis Research Center (NAG3-1677) and the Center for the S... more $^{a}$ Financial support from the NASA Lewis Research Center (NAG3-1677) and the Center for the Study of Terrestrial and Extraterrestrial Atmospheres (NASA NAGW-2950) is gratefully acknowledged.
Electromagnetism for Signal Processing, Spectroscopy and Contemporary Computing, 2021
RS Ser, V449 Per, MR Del, V593 Cen, and V1095 Her are short-period eclipsing binaries. We made ph... more RS Ser, V449 Per, MR Del, V593 Cen, and V1095 Her are short-period eclipsing binaries. We made photometric observations on 38 nights using four 1-m-class telescopes and plotted eight light curves. We determined the spectral type of V449 Per as K0(±2)V using low-resolution spectra from the Lijiang 2.4-m telescope. We found cyclic variation in the orbital periods for RS Ser and V1095 Her, and confirmed the cyclic variation of MR Del. The periods of the hypothetical third bodies are close to the duration of observation, and the detected cycles are questionable. For V593 Cen, we followed the previously published suggestion that it probably has a black hole with a minimum mass of 3.68 M⊙. We used the orbital period decreasing at a rate of 8.2(0.1) × 10−8 d yr–1 to explain it. There are two alternative interpretations, and hence the black hole candidate of V593 Cen remains questionable because the minimum points are concentrated in four clusters. The period of V449 Per increases continuou...
Springer Proceedings in Physics, 2016
The thermal characterization of single-walled carbon nanotubes (SWCNTs) and tungsten oxide (WO3)-... more The thermal characterization of single-walled carbon nanotubes (SWCNTs) and tungsten oxide (WO3)-based nanomaterials through the use of Raman spectroscopy is the primary aim of this study, and is focused mainly on the applications of SWCNTs for energy storage and WO3for toxic gas sensing, respectively. In the case of SWCNTs, the properties relevant to their performance obtained via resonant Raman spectroscopy were thermal expansion and thermal conductivity through the exploitation of the latter property’s relationship to the thermal behavior of the Raman G+-band of SWCNTs. In the case of the tungsten oxide-based nanomaterials, the responses of the various Raman signature peaks to different external stimuli, such as temperature variation, humidity changes, and toxic gas exposure, under controlled conditions were investigated.
Modeling, Characterization, and Production of Nanomaterials, 2015
Graphitic nanomaterials, such as graphene and carbon nanotubes, have been of particular interest ... more Graphitic nanomaterials, such as graphene and carbon nanotubes, have been of particular interest in the development of applications such as supercapacitors, nanoprobes, drug delivery, biochemical sensors, and storage materials. This chapter will discuss the importance of researching these graphitic nanomaterials through Raman spectroscopy and molecular dynamics simulations. This chapter will also discuss results relating to thermal analysis of purified single-walled carbon nanotubes and the effects of increasing temperature on the Raman features of these materials. Finally, this chapter discusses the results of molecular dynamics simulations based on the Raman spectra thermal analysis results.
... Abstract: Reproductions of $CO^{+}$ spectra taken with this spectograph, recently modified fo... more ... Abstract: Reproductions of $CO^{+}$ spectra taken with this spectograph, recently modified for photographic recording of ultraviolet spectra, will be compared with spectra obtained earlier on a 3.4-m commercial Ebert spectrograph with a similar but smaller grating. ...
Liquids are incompressible fluids that move in response to applied forces. The dominant forces de... more Liquids are incompressible fluids that move in response to applied forces. The dominant forces determining the shape of a free interface of a liquid at rest are gravity and surface tension. On Earth, at length scales larger than a few millimeters, gravity typically dominates. The purpose of this experiment was to observe the behavior of water, a Newtonian fluid, and the effects of surface tension, without the dominating force of gravity. During this experiment, multiple syringes of two different sizes were used to eject water during a microgravity flight experiment, forming a liquid column between two contact points. The behavior of this column was recorded and analyzed to determine the maximum length reached before the column breaks off. The longest water column size observed was 5.29 cm using a 3 ml syringe and 6.48 cm using a 10 ml syringe, respectively, under the reduced gravity experimental conditions aboard the modified Boeing 727 jet aircraft.
This work reports the modeling and simulation of gas sensors made from pristine graphene nanoplat... more This work reports the modeling and simulation of gas sensors made from pristine graphene nanoplatelets (P-GnPs) using COMSOL Multiphysics software. The mass balance equation was solved while including contributions of electromigration flux. An example GnP-based gas sensor was simulated to undergo exposure to NO2 and CO gases at different concentrations to understand the effects of adsorption. Various electrical properties and the overall sensor responses were also studied as a function of gas concentration in order to determine how viable such sensors could be for target gases. The results herein show that the resistance of the P-GnP-based gas sensor decreases when exposed to NO2 gas whereas an opposite trend is seen when CO gas is used for exposures, ultimately suggesting that the P-GnPs exhibit p-type behavior. Sensitivities of 23 % and 60 % were achieved when the P-GnP-based gas sensor was exposed to 10 mol/m3 concentration of NO2 and CO at room temperature, respectively. The dat...
Graphene nanoplatelets (GnPs) are promising candidates for gas sensing applications because they ... more Graphene nanoplatelets (GnPs) are promising candidates for gas sensing applications because they have a high surface area to volume ratio, high conductivity, and a high temperature stability. Also, they cost less to synthesize, and they are lightweight, making them even more attractive than other 2D carbon-based materials. In this paper, the surface and structural properties of pristine and functionalized GnPs, specifically with carboxyl, ammonia, carboxyl, nitrogen, oxygen, fluorocarbon, and argon, were examined with Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction (XRD) to determine the functional groups present and effects of those groups on the structural and vibrational properties. We attribute certain features in the observed Raman spectra to the variations in concentration of the functionalized GnPs. XRD results show smaller crystallite sizes for functionalized GnPs samples that agree with images acquired with...
Spectroscopy and Characterization of Nanomaterials and Novel Materials, 2022
Astronomy & Astrophysics, 2022
Based on the two-epoch European Very Long Baseline Interferometry (VLBI) Network (EVN) archive da... more Based on the two-epoch European Very Long Baseline Interferometry (VLBI) Network (EVN) archive data from OH line observations of IIZw 096, we confirm that the high-resolution OH emission in this source mainly comes from two spots (OH1 and OH2) of component (comp) D1 of this merging system. We found no significant variations in the OH 1667 MHz line emission, including flux densities and peak positions. The OH 1665 MHz line emission is detected at about the 6σ level in the OH1 region by combining two epochs of EVN observations. By using archival data from the Very Long Baseline Array (VLBA), Very Large Array (VLA), and Atacama Large Millimeter Array (ALMA) observations, we investigated the properties of the environment of this component through H I, CO(3-2), and HCO+(4-3) lines and the multi-band radio continuum emission. We found that the comp D1 shows the brightest CO, HCO+ line emission, as well as multi-band radio continuum emission. The environment around D1 shows no clear veloci...
Raman Spectroscopy, 2018
This chapter showcases some of the versatility of Raman spectroscopic data as applied to the char... more This chapter showcases some of the versatility of Raman spectroscopic data as applied to the characterization of single (SWNT) and multi-walled (MWNT) carbon nanotubes, few layer graphene and functionalized graphene nanoplatelets, with an emphasis on gas-sensing applications. Specifically, water vapor and a variety of toxic gases (NO, NO 2 , and SO 2 at 500 ppm in gaseous nitrogen) have been targeted for detection over the temperature range 24-200 C. The structure of sp 2-hybridized carbon allotropes is reviewed and scanning electron microscopy (SEM) imagery utilized in conjunction with Raman spectroscopy to physically and spectrally characterize the various graphitic nanomaterials studied. A Kataura plot analysis associated with the Radial Breathing Mode (RBM) vibrations of SWNT has been used to identify possible chiralities in the graphitic samples employing 455, 532 and 780 nm laser excitation wavelengths to record the Raman spectra. The effect of temperature on the various Raman vibrational modes (RBM, G + and G À) has been investigated, along with a determination of the thermal conductivity of SWNT samples and correlation between the purity of the sample and the variation of the slope of the G + band with increasing laser power.
Advanced Solid State Lasers, 1996
ABSTRACT The results of Tb3+ - Re3+ donor-acceptor interaction analysis for rare-earth (Re3+) dop... more ABSTRACT The results of Tb3+ - Re3+ donor-acceptor interaction analysis for rare-earth (Re3+) doped TbF3 single crystal are represented. Possible applications of Sm3+- as well as Eu3+- coactivated stoichiometric Tb-hosts for conversion of Argon-laser radiation into “yellow-orange-red” are discussed.
Computational and Experimental Simulations in Engineering, 2019
The sp 2 carbonaceous molecules possess a single atomic type per unit cell, which makes these mat... more The sp 2 carbonaceous molecules possess a single atomic type per unit cell, which makes these materials very good candidates for quantum mechanical studies associated with their vibrational and electronic energy levels. Significant findings, such as the Kohn anomaly, electron-phonon interactions, and other exciton-related effects, associated with these molecules can be transported to other 2-D materials. Information derived from the distinctive Raman bands from a single layer of carbon atoms also aids in gaining insight into new physics from such materials and other graphitic nanomaterials. The present paper focuses on our investigations of the G, D, and G bands of graphene and graphite, and the specific information provided by each. The G-band peak located at~1586 cm −1 , shared by all sp 2 carbons, has been used by us extensively in the estimation of thermal conductivity and thermal expansion characteristics linked to single-walled carbon nanotubes. In addition, we have investigated functionalized graphene nanoplatelets. For all three materials (graphene, graphite, and functionalized graphene nanoplatelets), we made use of the relationship discovered by Tuinstra and Koenig based on the relative intensities of the D and G Raman bands. In addition to the analysis based on Raman spectroscopy of the nanomaterial samples, SEM visualization/dimensional analysis was also performed on the graphene nanoplatelet samples. The bulk macroscopic 3-D character of graphite was clearly apparent, in contrast to the 2-D nature of graphene. However, the graphene nanoplatelets exhibited both 2-D and 3-D characteristics, without one dimension dominating the other.
Electromagnetism for Signal Processing, Spectroscopy and Contemporary Computing, 2021
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Papers by Prabhakar Misra