moram sree satya bharati
@egov.uohyd.ac.in
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UNIVERSITY OF HYDERABAD
RESEARCH, TEACHING, or OTHER INTERESTS
Atomic and Molecular Physics, and Optics, Condensed Matter Physics, Materials Science, Metals and Alloys
Scopus Publications
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Scopus Publications
Sree Satya Bharati Moram, Chandu Byram, and Venugopal Rao Soma
Beilstein Institut
The present study investigates the effects of input wavelength (1064, 532, and 355 nm) and surrounding liquid environment (distilled water and aqueous NaCl solution) on the picosecond laser ablation on silver (Ag), gold (Au), and Ag/Au alloy targets. The efficacy of the laser ablation technique was meticulously evaluated by analyzing the ablation rates, surface plasmon resonance peak positions, and particle size distributions of the obtained colloids. The nanoparticles (NPs) were characterized using the techniques of UV–visible absorption, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Furthermore, NPs of various sizes ranging from 6 to 35 nm were loaded onto a filter paper by a simple and effective drop-casting approach to achieve flexible surface-enhanced Raman spectroscopy (SERS) substrates/sensors. These substrates were tested using a simple, portable Raman device to identify various hazardous chemicals (malachite green, methyl salicylate, and thiram). The stability of the substrates was also systematically investigated by determining the decay percentages in the SERS signals over 60 days. The optimized SERS substrate was subsequently employed to detect chemical warfare agent (CWA) simulants such as methyl salicylate (a CWA simulant for sulfur mustard) and dimethyl methyl phosphonate (has some structural similarities to the G-series nerve agents) at different laser excitations (325, 532, and 633 nm). A notably higher SERS efficiency for CWA simulants was observed at a 325 nm Raman excitation. Our findings reveal that a higher ablation yield was observed at IR irradiation than those obtained at the other wavelengths. A size decrease of the NPs was noticed by changing the liquid environment to an electrolyte. These findings have significant implications for developing more efficient and stable SERS substrates for chemical detection applications.
Jagannath Rathod, Sree Satya Bharati Moram, Byram Chandu, Paweł Albrycht, and Venugopal Rao Soma
IOP Publishing
Abstract We present a simple, fast, and single-step approach for fabricating hybrid semiconductor-metal nanoentities through liquid-assisted ultrafast (∼50 fs, 1 kHz, 800 nm) laser ablation. Femtosecond (fs) ablation of Germanium (Ge) substrate was executed in (i) distilled water (ii) silver nitrate (AgNO3—3, 5, 10 mM) (iii) Chloroauric acid (HAuCl4—3, 5, 10 mM), yielding the formation of pure Ge, hybrid Ge-silver (Ag), Ge-gold (Au) nanostructures (NSs) and nanoparticles (NPs). The morphological features and corresponding elemental compositions of Ge, Ge-Ag, and Ge-Au NSs/NPs have been conscientiously studied using different characterization techniques. Most importantly, the deposition of Ag/Au NPs on the Ge substrate and their size variation were thoroughly investigated by changing the precursor concentration. By increasing the precursor concentration (from 3 mM to 10 mM), the deposited Au NPs and Ag NPs’ size on the Ge nanostructured surface was increased from ∼46 nm to ∼100 nm and from ∼43 nm to ∼70 nm, respectively. Subsequently, the as-fabricated hybrid (Ge-Au/Ge-Ag) NSs were effectively utilized to detect diverse hazardous molecules (e.g. picric acid and thiram) via the technique of surface-enhanced Raman scattering (SERS). Our findings revealed that the hybrid SERS substrates achieved at 5 mM precursor concentration of Ag (denoted as Ge-5Ag) and Au (denoted as Ge-5Au) had demonstrated superior sensitivity with the enhancement factors of ∼2.5 × 104, 1.38 × 104 (for PA), and ∼9.7 × 105 and 9.2 × 104 (for thiram), respectively. Interestingly, the Ge-5Ag substrate has exhibited ∼10.5 times higher SERS signals than the Ge-5Au substrate.
Sampath Kumar Satani, Sree Satya Bharati Moram, and Venugopal Rao Soma
IOP Publishing
Abstract Currently, flexible surface-enhanced Raman spectroscopy (SERS) substrates have gained tremendous interest because they enable sample collection from uneven surfaces in real sensing applications. Herein, two different flexible textiles (cotton and synthetic fabrics) loaded with star-shaped gold (Au) nanoparticles (NPs) were utilized for detailed studies and are demonstrated as SERS substrates. Both fabrics were soaked in Au NPs synthesized via a simple wet chemical method. The colloidal star-shaped Au NPs were characterized by UV-visible absorption and transmission electron microscopy techniques. The C- and S-fabrics loaded with Au NPs were characterized by FESEM, x-ray diffraction, and x-ray photoelectron spectroscopic techniques. Subsequently, the SERS efficiency of C- and S-fabrics was examined with thiram, methylene Blue (MB), and Nile Blue (NB) molecules. Furthermore, pesticide (thiram) residues on the surfaces of a banana, an apple, and a spinach leaf were investigated by a simple swabbing method. The utility of these substrates is demonstrated by performing the SERS measurements using a portable Raman spectrometer, which is expedient for real-time applications.
Sree Satya Bharati Moram, Jagannath Rathod, Dipanjan Banerjee, and Venugopal Rao Soma
MyJove Corporation
The technique of ultrafast laser ablation in liquids has evolved and matured over the past decade, with several impending applications in various fields such as sensing, catalysis, and medicine. The exceptional feature of this technique is the formation of nanoparticles (colloids) and nanostructures (solids) in a single experiment with ultrashort laser pulses. We have been working on this technique for the past few years, investigating its potential using the surface-enhanced Raman scattering (SERS) technique in hazardous materials sensing applications. Ultrafast laser-ablated substrates (solids and colloids) could detect several analyte molecules at the trace levels/mixture form, including dyes, explosives, pesticides, and biomolecules. Here, we present some of the results achieved using the targets of Ag, Au, Ag-Au, and Si. We have optimized the nanostructures (NSs) and nanoparticles (NPs) obtained (in liquids and air) using different pulse durations, wavelengths, energies, pulse shapes, and writing geometries. Thus, various NSs and NPs were tested for their efficiency in sensing numerous analyte molecules using a simple, portable Raman spectrometer. This methodology, once optimized, paves the way for on-field sensing applications. We discuss the protocols in (a) synthesizing the NPs/NSs via laser ablation, (b) characterization of NPs/NSs, and (c) their utilization in the SERS-based sensing studies.
Chandu Byram, Sree Satya Bharati Moram, Dipanjan Banerjee, Reshma Beeram, Jagannath Rathod, and Venugopal Rao Soma
IOP Publishing
Abstract Since its discovery, the laser ablation in liquid (LAL) technique has engrossed significant attention from the research community. It is gradually becoming a fascinating fabrication technique to synthesize nanostructures (NSs) of diverse morphologies on solid targets as well as nanoparticles (NPs) with distinct shapes/sizes in a single attempt. Moreover, this technique has a plethora of advantages over the chemical routes, such as simplicity, robustness, and purity of the produced NPs/NSs, as well as the circumvention of stabilizing reagents and/or chemical precursors during the synthesis procedure. The present review focuses on our research group’s significant contributions and achievements over the past 10 years on laser-synthesized nanomaterials and their applications in sensing using the technique of surface-enhanced Raman spectroscopy and third-order nonlinear optics/photonics. We highlight in the first section the governing mechanisms involved in the LAL technique with laser pulses of different duration such as nanosecond, picosecond, and femtosecond. The subsequent section discusses the effect of input laser pulse parameters (wavelength, fluence, pulse duration, reputation rate, and the number of pulses) as well as surrounding ambience (air and liquid) on the morphological changes of the substrate’s surfaces used in the production of NPs and surface NSs. The later section of this review describes the overview of LAL applications with particular emphasis on surface-enhanced Raman scattering-based hazardous materials sensing and nonlinear optics/photonics.
Sree Satya Bharati Moram, Chandu Byram, and Venugopal Rao Soma
Royal Society of Chemistry (RSC)
We have developed simple and cost-effective hybrid surface-enhanced Raman scattering (SERS) substrates comprising fs laser patterned Si surfaces and chemically prepared gold nanostars for the trace detection of pesticide and dye molecules.
M.S.S. Bharathi, Dipanjan Banerjee, and Venugopal Rao Soma
Optica Publishing Group
A hybrid metal-semiconductor SERS substrate was fabricated in a single step by femtosecond laser ablation in liquid. Ag-TiO2 nanostructure was employed in the SERS studies, revealing a 16 times superior signal than pure TiO2 nanostructures.
Dipanjan Banerjee, Sree Satya Bharathi Moram, and Venugopal Rao Soma
Optica Publishing Group
In this study, the femtosecond laser ablation technique was engaged to fabricate silver-doped titanium dioxide nanoparticles. Further, these NPs were employed in surface-enhanced Raman scattering-based sensing of RDX and ammonium nitrate traces.
Amrita M., Rukmini Srikant Revuru, Sreeram Chatti, Sree Satya Bharati Sri Satya Moram, Chandu Byram, and Venugopal Rao Soma
Emerald
Purpose Ti6Al4V is a commonly used titanium alloy with several applications in aerospace industry due to its excellent strength to weight ratio. But due to low thermal conductivity, it is categorized as “difficult to machine.” Though machinability can be improved with cutting fluids, it is not preferred due to associated problems. This study aims at eliminating the use of cutting fluid and finding an alternate solution to dry machining of Ti6Al4V. AlTiN coated tools provide good heat and oxidation resistance but have low lubricity. In the present work, graphene, which is known for lubricating properties, is added to the tools using five different methods (tool condition) to form graphene self-lubricated cutting tools. Design/methodology/approach Graphene-based self-lubricating tools are prepared by using five methods: dip coating (10 dips and 30 dips); drop casting; and filling of micro/macroholes. Performance of these tools is evaluated in terms of cutting forces, surface roughness and tool wear by machining Ti6Al4V and comparing with conventional coated cutting tool. Findings Self-lubricating tool with micro holes filled with graphene outperformed other tools and showed maximum decrease of 33.42% in resultant cutting forces, 35% in surface roughness (Ra) and 30% in flank wear compared to conventional cutting tool. Originality/value Analysis of variance for all forces show that tool condition and machining time have significant influence on all components of cutting forces and resultant cutting forces.
M. Haribabu, B. Dipanjan, M.S.S. Bharati, J. Chelsea, A. Chandrasekhar, P. Kanaka raju, S. Venugopal Rao, S. Hamad, and G. Krishna Podagatlapalli
Elsevier BV
Linga Murthy Narlagiri, M.S.S. Bharati, Reshma Beeram, Dipanjan Banerjee, and Venugopal Rao Soma
Elsevier BV
Chandu Byram, Jagannath Rathod, Sree Satya Bharati Moram, Akkanaboina Mangababu, and Venugopal Rao Soma
MDPI AG
Recently, filter paper (FP)-based surface-enhanced Raman scattering (SERS) substrates have stimulated significant attention owing to their promising advantages such as being low-cost, easy to handle, and practically suitable for real-field applications in comparison to the solid-based substrates. Herein, a simple and versatile approach of laser-ablation in liquid for the fabrication of silver (Ag)-gold (Au) alloy nanoparticles (NPs). Next, the optimization of flexible base substrate (sandpaper, printing paper, and FP) and the FP the soaking time (5–60 min) was studied. Further, the optimized FP with 30 min-soaked SERS sensors were exploited to detect minuscule concentrations of pesticide (thiram-50 nM), dye (Nile blue-5 nM), and an explosive (RDX-1,3,5-Trinitroperhydro-1,3,5-triazine-100 nM) molecule. Interestingly, a prominent SERS effect was observed from the Au NPs exhibiting satisfactory reproducibility in the SERS signals over ~1 cm2 area for all of the molecules inspected with enhancement factors of ~105 and relative standard deviation values of <15%. Furthermore, traces of pesticide residues on the surface of a banana and RDX on the glass slide were swabbed with the optimized FP substrate and successfully recorded the SERS spectra using a portable Raman spectrometer. This signifies the great potential application of such low-cost, flexible substrates in the future real-life fields.
Jagannath Rathod, Chandu Byram, Ravi Kumar Kanaka, Moram Sree Satya Bharati, Dipanjan Banerjee, Mangababu Akkanaboina, and Venugopal Rao Soma
American Chemical Society (ACS)
We report the fabrication and performance evaluation of hybrid surface-enhanced Raman scattering (SERS) substrates involving laser ablation and chemical routes for the trace-level detection of various analyte molecules. Initially, picosecond laser ablation experiments under ambient conditions were performed on pure silver (Ag) and gold (Au) substrates to achieve distinct nanosized features on the surface. The properties of the generated surface features on laser-processed portions of Ag/Au targets were systematically analyzed using UV–visible reflection and field emission scanning electron microscopy studies. Later, hybrid-SERS substrates were achieved by grafting the chemically synthesized Au nanostars on the plain and laser-processed plasmonic targets. Subsequently, we employed these as SERS platforms for the detection of a pesticide (thiram), a molecule used in explosive compositions [ammonium nitrate (AN)], and a dye molecule [Nile blue (NB)]. A comparative SERS study between the Au nanostar-decorated bare glass, silicon, Ag, Au, and laser-processed Ag and Au targets has been established. Our studies and the obtained data have unambiguously determined that laser-processed Ag structures have demonstrated reasonably good enhancements in the Raman signal intensities for distinct analytes among other substrates. Importantly, the fabricated hybrid SERS substrate of “Au nanostar-decorated laser-processed Ag” exhibited up to eight times enhancement in the SERS intensity compared to laser-processed Ag (without nanostars), as well as up to three times enhancement than the Au nanostar-loaded plain Ag substrates. Additionally, the achieved detection limits from the Au nanostar-decorated laser-processed Ag SERS substrate were ∼50 pM, ∼5 nM, and ∼5 μM for NB, thiram, and AN, respectively. The estimated enhancement factors accomplished from the Au nanostar-decorated laser-processed Ag substrate were ∼106, ∼106, and ∼104 for NB, thiram, and AN, respectively.
Kanaka Ravi Kumar, B. Chandu, M.S.S. Bharati, M. Mallikarjuna Rao, S. Venugopal Rao, and S.V.S. Nageswara Rao
IOP Publishing
We report on the ultrafast (femtosecond) laser ablation of monocrystalline Si (100), polycrystalline Si, and Si (100) capped with a SiO2 layer. The target material was ablated using femtosecond laser pulses (~50 fs duration, 1 kHz repetition rate, and 800 nm wavelength) with an input energy of ~100 μJ in acetone medium to fabricate Si Nanoparticles (NPs). The average size of NPs produced by Si (100) was found to be less than that of the particles produced by poly Si. Ablation of Si caped with SiO2 resulted in bigger Si NPs together with a low concentration of SiO2 NPs. NPs were found to be of polycrystalline in all three cases irrespective of the initial phase.
N Linga Murthy, M S S Bharathi, and S Venugopal Rao
IOP Publishing
Laser induced breakdown spectroscopy (LIBS) technique in conjunction with nanoparticles improves the sensitivity in the detection of solids like metals, precious gemstones and liquid samples. Femtosecond (fs) LIBS signals can also be enhanced in the presence of nanoparticles. We demonstrated up to two–time enhancement in the fs LIBS spectra of aluminum sheet coated with the gold nanoparticles embedded polyvinyl alcohol (PVA) nanofibers. Gold nanoparticles were fabricated using the fs laser ablation in liquid technique, the mean size of the nanoparticles was 10-15 nm. PVA nanofibers and are loaded Gold nanoparticles were prepared by electrospinning technique. The enhancements were observed in both the atomic and molecular (AlO) emissions. The technique can further be optimized for obtaining signal enhancement in the molecular bands of explosive traces.
M. Amrita, Kamesh B, Srikant R R, Bharati MSS, Chandu B, and Venugopal Rao Soma
Universiti Malaysia Pahang Publishing
Ti6Al4V has wide applications but is generally considered to belong to the “difficult to machine” category. The present work aims at evaluating sustainability while machining Ti6Al4V with inclusion of graphene. Graphene is included using two methods in this work. In method one, graphene is included as a dispersant in cutting fluid and applied as minimum quantity lubrication (MQL). In the other method, graphene is filled in microholes on tools to form self-lubricating tools. Experiments are performed, and results are used to evaluate carbon footprint of the operation on the environment. Economic analysis is also performed—application of graphene as dispersant as well as in solid form enhanced machining capability of Ti6Al4V. Application of 0.3 wt.% graphene dispersed cutting fluid is found to be the most economic. The use of graphene in both forms could improve the machinability of Ti6Al4V and is also found to be economical but has enhanced carbon emission to the environment.
Maddamasetty Amrita, Bodduru Kamesh, Rukmini Srikant Revuru, M.S.S. Bharati, B. Chandu, and S. Venugopal Rao
Inderscience Publishers
Dipanjan Banerjee, Sree Satya Bharati Moram, Chandu Byram, Jagganath Rathod, Twinkle Jena, Gopala Krishna Podagatlapalli, and Venugopal Rao Soma
Elsevier BV
M S S Bharathi, Chandu Byram, D Banerjee, D Sarma, B Barkakaty, and Venugopal Rao Soma
Springer Science and Business Media LLC
Tania K. Naqvi, Abhilash Bajpai, Moram Sree Satya Bharati, Manish M. Kulkarni, Azher M. Siddiqui, Venugopal Rao Soma, and Prabhat K. Dwivedi
Elsevier BV
Yalambaku Rajesh, M. S. S. Bharati, S. Venugopal Rao, and M. Ghanashyam Krishna
Springer Science and Business Media LLC
Moram Sree Satya Bharati, , and Venugopal Rao Soma
Opto-Electronic Advances
This article reviews the most recent advances in the development of flexible substrates used as surface-enhanced Raman scattering (SERS) platforms for detecting several hazardous materials (e.g., explosives, pesticides, drugs, and dyes). Different flexible platforms such as papers/filter papers, fabrics, polymer nanofibers, and cellulose fibers have been investigated over the last few years and their SERS efficacies have been evaluated. We start with an introduction of the importance of hazardous materials trace detection followed by a summary of different SERS methodologies with particular attention on flexible substrates and their advantages over the nanostructures and nanoparticle-based solid/hybrid substrates. The potential of flexible SERS substrates, in conjunction with a simple portable Raman spectrometer, is the power to enable practical/on-field/point of interest applications primarily because of their low-cost and easy sampling.
Moram Sree Satya Bharati, Byram Chandu, Sri Bhavya Muvva, and Soma Venugopal Rao
Springer Singapore
Chandu Byram, Sree Sathya Bharathi Moram, and Venugopal Rao Soma
Springer Singapore