A5071913751- Ion-surface interactions and analysis
- Theoretical and Computational Physics
- Quantum Dots Synthesis And Properties
- Semiconductor Quantum Structures and Devices
- Conducting polymers and applications
- Surface and Thin Film Phenomena
- Lipid Membrane Structure and Behavior
- Electron and X-Ray Spectroscopy Techniques
- X-ray Diffraction in Crystallography
- Integrated Circuits and Semiconductor Failure Analysis
- Quasicrystal Structures and Properties
- Surface Roughness and Optical Measurements
- Spectroscopy and Quantum Chemical Studies
- Advanced Memory and Neural Computing
- Gold and Silver Nanoparticles Synthesis and Applications
- Magnetic properties of thin films
- Semiconductor materials and devices
- Surfactants and Colloidal Systems
- Organic Electronics and Photovoltaics
- Force Microscopy Techniques and Applications
- Material Dynamics and Properties
- Advanced Surface Polishing Techniques
- Silicon Nanostructures and Photoluminescence
- Mineralogy and Gemology Studies
- Characterization and Applications of Magnetic Nanoparticles
Saha Institute of Nuclear Physics
2016-2025
Homi Bhabha National Institute
2022-2024
S.N. Bose National Centre for Basic Sciences
2008-2021
Jawaharlal Nehru Centre for Advanced Scientific Research
2004-2019
Calcutta Research Group
2019
Max Planck Society
2010
CEA Paris-Saclay
2008
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2008
European Synchrotron Radiation Facility
2008
CEA Grenoble
2008
Abstract The development of synthetic processes for oxide nanomaterials is an issue considerable topical interest. While a number chemical methods are available and extensively used, the collaborations often energy intensive employ toxic chemicals. On other hand, synthesis inorganic materials by biological systems characterized that occur at close to ambient temperatures pressures, neutral pH (examples include magnetotactic bacteria, diatoms, S‐layer bacteria). Here we show nanoparticulate...
A study of the scattering x rays from liquid-vapor interface ethanol at room temperature is reported and compared in detail to predictions based on standard continuum capillary-wave theory. Quantitative agreement obtained and, particular, asymptotic power laws diffuse characteristic algebraic decay density-fluctuation correlations surface are verified. The root-mean-square fluctuation liquid as 6.9\ifmmode\pm\else\textpm\fi{}0.2 \AA{}.
X-ray-based analytics are routinely applied in many fields, including physics, chemistry, materials science, and engineering. The full potential of such techniques the life sciences medicine, however, has not yet been fully exploited. We highlight current upcoming advances this direction. describe different methodologies (including those performed at synchrotron light sources X-ray free-electron lasers) their potentials for application to investigate nano–bio interface. discussion is...
Polyethylene propylene films of various molecular weights, which would normally wet native-oxide-covered Si surfaces, were observed to dewet the surface when film thickness became less than polymer radius gyration. These could be made either by increasing annealing temperature or chemically modifying surface. The results are shown consistent with an expression for spreading parameter that incorporates a stretching free energy term chains. Measurements diffusion constant on silica indicated...
A spin-coated thin polystyrene film on a silicon single crystal has been studied using the X-ray reflectivity technique. Signature of layering as function depth, due to confinement, in this could be detected from profile new analysis scheme. Small variations electron density across depth can determined data scheme with no priori distribution profile.
Ion-beam-induced ripple formation in Si wafers was studied by two complementary surface sensitive techniques, namely atomic force microscopy (AFM) and depth-resolved x-ray grazing incidence diffraction (GID). The of structure at high doses $(\ensuremath{\sim}7\mathbf{\ifmmode\times\else\texttimes\fi{}}{10}^{17}\phantom{\rule{0.3em}{0ex}}\mathrm{ions}∕{\mathrm{cm}}^{2})$, starting from initiation low...
Kinetics of order-disorder transitions including melting in low-dimensional systems is theoretically predicted to be heterogeneous that start by nucleation defect sites at lower than homogeneous bulk-melting temperature requiring substantially energy barrier. We probed kinetics such transition thin multilayered films using x-ray scattering and situ atomic force microscopy (AFM) studies. X-ray results show linear increase with time in-plane separation ordered domains while AFM measurements a...
The emerging class of hybrid organic-inorganic perovskites (HOIPs) has exhibited fascinating properties for a wide range technological applications. With halide ions, HOIPs have provided novel optoelectronic devices including efficient solar cells and with pseudohalide anions-like formate (HCOO-), enigmatic electromagnetic been obtained in HOIPs. Large-scale synthesis such 2D HOIP films is immense importance the advancement its application as materials. We shown using in-situ X-ray...
The morphology and growth mechanism of silver films approximately 150 Å in thickness on Si(001) substrates have been studied by atomic force microscopy x-ray reflectivity. thin prepared dc sputtering at room temperature are composed islands silver. shape size distribution these using two complementary measurement techniques.
The use of X-ray and neutron reflectivity measurements to determine the density profile across interface or thin films has become increasingly popular over last few years. However, in general convenient model-independent methods inverting profiles obtain have been missing. We present here one such approach using method anomalous from substrate demonstrate its applicability case an organic film.
A basic understanding of the properties thin polymer films is fundamental importance for developing applications in nanotechnology. Results energy and angle dispersive x-ray reflectivity measurements on as a function temperature exhibit reversible negative thermal expansion below glass transition T(g). Above T(g), thickness becomes almost equal to expected bulk volume expansion. These results could be explained basis evolution disorder with at interfaces, chain entanglement associated...
Wavelength variation of ion beam induced nanoscale ripple structure has received much attention recently due to its possible application in nanotechnology. We present here results Ar$^+$ bombarded Si the energy range 50 140 keV demonstrate that with scanning wavelength increases and decreases for irradiation without scanning. An expression dependence is proposed taking into simultaneous effect thermally activated surface diffusion effective diffusion.
Microscopic measurements that provide direct information in nanometer length scales are essential to obtain a proper understanding of the interfacial reactions form nanostructured materials. We present here results synchrotron X-ray scattering study formation and ordering gold nanoparticles at toluene−water interface through reduction reaction. The observed reflectivity diffuse data show monolayer "magic clusters" water−toluene interface. Each cluster consists 13 with about 12 Å diameter,...
Formation of condensed films nanoparticles having small ratio metal-core-diameter to organic-shell-thickness is desired for several applications in nanotechnology. We report here results a X-ray scattering study carried out understand structure and morphology monolayer such gold-core thiol-shell directly on the water surface before undergoes continuous transition bilayer. Our demonstrate buckling over large pressure range (1 15 mN/m). The buckled state exhibits reversibility decompression...
The correlation of thin films structure and orientation small organic molecules with the physical properties like charge carrier transport is not only important for basic understanding but also crucial various application as functional devices. Small semiconductor assemble in different configuration resulting exhibiting a wide variety optoelectronic properties. Here, we have investigated three metal phthalocyanines (MPcs) having ion Cu, Co, Ni using combination x-ray scattering techniques...
Ferromagnetic ordering in nanocrystallites of dilute magnetic semiconductors arises due to a fascinating interplay carrier concentration, randomness impurity sites, and size-induced quantum confinement. We here report results magnetization study on ZnS nanoparticles $(\ensuremath{\sim}2.5\phantom{\rule{0.3em}{0ex}}\mathrm{nm})$ carried out by varying the doping concentration substitutional Mn ions that occupy cationic sites without altering concentration. giant Zeeman splitting are observed...
Langmuir-Blodgett (LB) deposition is an astonishingly simple technique to grow well-ordered correlated metal-organic multilayers. To understand this growth mechanism, we have performed x-ray scattering and atomic force microscopic (AFM) studies on cadmium arachidate LB films exhibiting self-affine logarithmic in-plane correlation at the interfaces. Using linear stochastic theory for interface evolution, it proposed that a 1D followed by 2D desorption process mechanism of films. X-ray AFM...
The behavior of mixed-ligand-coated gold nanoparticles at a liquid-liquid interface during compression has been investigated. system was characterized by measuring pressure-area isotherms and simultaneously performing in situ X-ray studies. Additionally, Monte Carlo (MC) simulations were carried out order to interpret the experimental findings. With this dual approach it possible characterize identify different stages understand what happens microscopically: first, purely in-plane, and,...
We have presented here results of a low temperature transport study polypyrrole nanowires having electron densities, which shows characteristics charge density waves observed in structurally ordered materials. The current-voltage all these show power-law dependence on voltage and ``gap'' that decreases rapidly as the is increased, confirming existence long-range electron-electron interaction nanowires. A switching transition to highly conducting state has been above threshold voltage, can be...
The influence of adding nanoparticles on the ascast morphology spin coated immiscible polystyrene/poly(methyl methacrylate) (PS/PMMA) thin films different thickness (hE) and composition (RB, volume ratio PS to PMMA) has been explored in this article. To understand precise effect nanoparticle addition, PS/PMMA blend cast from toluene a native oxide covered silicon wafer substrate was first investigated. It is seen that particle free films, generic remains nearly unaltered with increase hE,...
Abstract 2D organic–inorganic hybrid lead halide perovskite films are fascinating optoelectronic materials for white‐light emission and lasing applications. Here, it is demonstrated that nano‐meter‐thick of perovskites can be formed at room temperature using Langmuir–Schaefer (LS) deposition technique. In situ X‐ray measurements reveal a self‐assembly process the formation air–water interface. This requires presence stearic acid monolayer on water subphase having solution lead‐perovskite in...