Howard University Graduate School

HUGS Research Magazine
and Graduate School Research Archive


New Developments in Applied Spectroscopy and Nanomaterials

By Gwendolyn S. Bethea, Ph.D.

Dr. Misra

Prabhakar Misra, Ph.D., professor of physics and director of the Laser Spectroscopy Laboratory; editor, Applied Spectroscopy and the Science of Nanomaterials (Progress in Optical Science and Photonics).

Figure 1 - A schematic of the experimental arrangement used for recording the Raman spectra of the Carbon Nanotube (CNT) samples. Created by Raul Garcia-Sanchez, Doctoral Candidate, Physics

Figure 2 - (Top, 12, 1) Chirality of single-wall nanotube; and (Bottom) Distortion of circular cross-section of a nanotube. Created by Daniel Casimir.

The above figures were adapted from the chapter titled "Raman Spectroscopy, Modeling and Simulation Studies of Carbon Nanotubes." Daniel Casimir, Raul Garcia-Sanchez and Prabhakar Misra, in Applied Spectroscopy and the Science of Nanomaterials (Progress in Optical Science and Photonics, Vol.2. New York: Springer, 2015, ISBN 978-981-287-241-8), Prabhakar Misra (Editor).

Prabhakar Misra, Ph.D., professor of physics and director of the Laser Spectroscopy Laboratory, recently edited the book, Applied Spectroscopy and the Science of Nanomaterials (Progress in Optical Science and Photonics, Vol.2. New York: Springer, 2015, ISBN 978-981-287-241-8), with chapter contributions from experts in the field. The book focuses on several areas of current interest, including:

• Raman spectroscopic characterization, modeling and simulation studies of carbon nanotubes,
• Characterization of plasma discharges using laser optogalvanic spectroscopy,
• Fluorescence anisotropy in understanding protein conformational disorder and aggregation,
• Nuclear magnetic resonance spectroscopy in nanomedicine
• Calculation of Van der Waals interactions at the nanoscale,
• Theory and simulation associated with adsorption of gases in nanomaterials,
• Atom-precise metal nanoclusters,
• Plasmonic properties of metallic nanostructures, two-dimensional materials, and their composites,
• Applications of graphene in optoelectronic devices and transistors,
• Role of graphene in organic photovoltaic device technology,
• Applications of nanomaterials in nanomedicine.

An online interview with Dr. Misra follows:

Q: When and how did you discover your interest in the physics discipline and how did your particular interest in editing a book on applied spectroscopy and nanomaterials evolve?
Dr. Misra: My passion for physics goes back to my formative years during my high school days in Calcutta, India. I was drawn to physics because it went beyond mathematics and it could explain everyday phenomena in fairly easy to understand terms, both qualitatively and quantitatively. From the moment you get up from bed to the time you go to sleep, the laws of physics govern your every movement, including falls on black ice on the driveway during the winter – due to lack of traction - as you try to retrieve your morning newspaper!

I have co-edited two books in the past, which have been well-received in the scientific community, namely "Ultraviolet Spectroscopy and UV Lasers", P. Misra and M. Dubinskii, Editors, Marcel Dekker, New York, 2002 (ISBN: 0-8247-0668-4) and "Fundamentals & Current Topics in Molecular Structure Research," P. Misra and C. Haridas, Editors, Research SignPost, Kerala, India, 2011 (ISBN: 978-81-308-0458-3). The origin of the present book took shape in Singapore in February 2013 at the Annual International Conference in Optoelectronics, Photonics and Applied Physics (OPAP 2013), where I was presenting an invited paper and had the good fortune of interacting with Mr. Loyola D’Silva of the Springer Publishing House, after he had made the initial contact a few months earlier and had extended an invitation via e-mail requesting me to consider editing a book in their series relating to Progress in Optical Science and Photonics.

Q: In the book, the experts examine several developments in applied spectroscopy and the science of nanomaterials. Would you provide a few of these recent developments, including in the field of medicine?
Dr. Misra: The current book Applied Spectroscopy and the Science of Nanomaterials is a synergistic compendium of eleven informative and cutting-edge chapters written by leading researchers in the field of spectroscopy and condensed matter physics as applied to a variety of materials at the nanoscale. In the leading chapter titled "Raman Spectroscopy, Modeling and Simulation Studies of Carbon Nanotubes", the authors (Casimir, Garcia-Sanchez & Misra) focus on the thermal characteristics of carbon nanotubes (CNTs), which are allotropes of carbon and consist of the so-called sp2-hybridized carbon atoms. Such thermal investigations lead to a clearer understanding of the chirality of nanotubes through the visualization of rolled-up graphene sheets, and in turn provide insight into the versatility and myriad thermo-mechanical and electrical properties that make CNTs excellent candidates for a wide variety of applications in nanoelectronics and the semiconductor industry. In the chapter titled "Applications of Fluorescence Anisotropy in Understanding Protein Conformational Disorder and Aggregation" the authors (Jain & Mukhopadhyay) focus on the applications of fluorescence spectroscopy in better understanding how proteins misfold and aggregate, leading to the formation of nanoscopic amyloid fibrils that are implicated in a range of human diseases. Some examples of amyloid diseases include Alzheimer's, Type 2 Diabetes, and Mad Cow disease.

Q: What other fields are directly related to these developments?
Dr. Misra: Materials science and nanotechnology are directly related to the above-cited research developments. The awarding of the 2010 Nobel Prize in Physics to Andre Geim and Konstantin Novoselov of the University of Manchester, UK, for "…groundbreaking experiments regarding the two-dimensional material graphene…" recognized a new chapter in carbon research and was a testament to the significance of the field of nanophysics and nanostructures of materials.

In the chapter titled "Adsorption of Gases in Nanomaterials: Theory and Simulations", the authors (Mbaye, Maiga and Gatica) describe the theory and simulation associated with the adsorption of gases in nanomaterials. Physical adsorption (physisorption) is a term applied to atoms or molecules that are weakly bound to surfaces and its applications include the separation of cryogenic gases and their storage. In particular, the chapter covers equilibrium properties of gases adsorbed in CNTs, graphene and Metal Organic Frameworks (MOFs). The behavior of adsorbed matter at the nanoscale is dramatically different from the corresponding bulk material, due in part to the reduced dimensionality. Based on the simulations of adsorbed gases in nanomaterials, the authors predict novel phases that have not yet been observed, presenting challenges and opportunities to make significant breakthroughs in understanding intriguing new phenomena linked with the behavior of adsorbed molecules at the nanoscale.

Q: Would you give us a glimpse into the future in these areas and do you predict that we will see them come to fruition in our lifetime?
Dr. Misra: Graphene, with its highly regular honeycomb structure, presents the prospect of developing graphene-based transistors that have the potential of reaching speeds of about 100 GHz, while at the same time being three times smaller than traditional silicon-based transistors. Another important property of graphene is its tensile strength of about 100-GPa, which is roughly forty times greater than the corresponding value for steel. The remarkable properties of nanomaterials may help usher in a diverse array of future technologies and applications, ranging from solar panels and transparent touch screens to ultra-strong composites that might make the wondrous so-called "space elevator" a reality. A space elevator has been envisioned as a cable fixed to the equator and extending into space to the height of a geostationary orbit. The space elevator cable would rotate along with the Earth’s rotation. A counterweight can be designed for the upper end of the cable that would keep the center of mass above the geostationary level. As a consequence, the upwardly directed centrifugal force due to the Earth’s rotation would exactly balance the downward gravitational force and maintain the cable upright and rigid, whereby climbers could move up and down the cable at will! Whether these marvels will happen in our lifetime is hard to predict, but one never knows!

Q: What are you currently researching in your own laboratory?
Dr. Misra: I am currently involved in the detailed characterization of a variety of nanomaterials (e.g. graphene, carbon nanotubes and metal oxides) using Raman Spectroscopy and Molecular Dynamics Simulations. The first two chapters in the book, namely "Raman Spectroscopy, Modeling and Simulation Studies of Carbon Nanotubes" and "Laser Optogalvanic Spectroscopy and Collisional State Dynamics Associated with Hollow Cathode Discharge Plasmas", provide an overview of two of the major areas of research being pursued in my research laboratory.

Q: How are undergraduate and graduate students involved in the research of your own laboratory?
Dr. Misra: Currently, I am supervising the research of two graduate students, Daniel Casimir and Raul Garcia-Sanchez, who will be completing their Ph.D. dissertations fairly soon. Daniel’s dissertation is titled "Investigation of Thermal Expansion Properties of Single Walled Carbon Nanotubes by Raman Spectroscopy and Molecular Dynamics Simulation", while Raul’s Ph.D. research centers on the "Characterization of Metal Oxide Gas Sensors Using Raman Spectroscopy and Computer Simulations". There are also three undergraduate physics majors who are part of my research group: Janelle Holmes, Naomi Haddock and Kyia Rutherford. Janelle is working on a project titled "Lunar South Pole Space Weather" being pursued in collaboration with Dr. William Farrell of NASA Goddard Space Flight Center as part of the Dynamic Response of the Environments at Asteroids, the Moon, and moons of Mars (DREAM2) project. Naomi is involved in using a PASCO physics software package to understand how gravity and friction affect the dynamics of motion and collisions between bodies on impact with the ultimate aim of understanding the effects of microgravity, while Kyia is bringing up to speed a Fourier Transform Infrared (FTIR) spectrometer to characterize nanomaterials in the mid-infrared to complement the Raman spectroscopy measurements.

Q: What are some examples of nanoscience and nanomaterials?
Dr. Misra: Examples of nanoscience and nanomaterials are all around us. One simple example is the pervasiveness of natural colloids (e.g. milk, gelatin, custard, blood, smoke, etc.). In general terms, a colloid is comprised of particles that have sizes in the range 10-300 nanometers, whereby the nanosize constituent particles get dispersed evenly and thus the colloid has a homogeneous appearance. Milk is white because it is made up of colloidal nanoparticles (called micelles). If the structure of micelles is altered, we get a different product (e.g. milk gets converted to cheese or yogurt). This is a fundamental concept in nanotechnology - new materials can be engineered with novel functions from the manipulation of the molecular reorganization. Another interesting example is the manufacture of energy-scavenging fabrics based on nano-sized piezoelectric generators, whereby so-called "smart" clothes can be powered using integrated electronics and sensors via simple body movements.

Q: What are the personal rewards that you have found over the 26 plus years of your teaching and mentoring students?
Dr. Misra: The personal rewards have been my active research involvement with graduate and undergraduate students over the years and nurturing them to mature and transition from the class room and the laboratory to become independent researchers in the workforce with effective technical oral and written communication skills.

Daniel Casimir
Daniel Casimir, Doctoral Candidate, Physics, characterizing the carbon nanotubes with a Thermofisher DXR Smart Raman Spectrometer for the book, Applied Spectroscopy and the Science of Nanomaterials.

Raul Garcia-Sanchez

Janelle Holmes

Naomi Haddock

Kyia Rutherford

Raul Garcia-Sanchez, Doctoral Candidate, Physics, conducted research for new book, Applied Spectroscopy and the Science of Nanomaterials.

Physics undergraduate students, Janelle Holmes, Naomi Haddock, and Kyia Rutherford, are conducting research in Dr. Misra’s laboratory.

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