Pradip Kumar Roy

University of Chemistry and Technology, Prague

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Trends

Author Order

Document Type

Co-Authors

Zdeněk Sofer

University of Chemistry and Technology, Prague

Yang‐Fang Chen

National Taiwan University

Golam Haider

Czech Academy of Sciences, J. Heyrovský Institute of Physical Chemistry

Hung‐I Lin

Massachusetts Institute of Technology

Surojit Chattopadhyay

National Yang Ming Chiao Tung University

Yu‐Ming Liao

National Taiwan Ocean University

Jan Luxa

University of Chemistry and Technology, Prague

Nikolas Antonatos

University of Chemistry and Technology, Prague

Vlastimil Mazánek

University of Chemistry and Technology, Prague

Jalal Azadmanjiri

University of Chemistry and Technology, Prague

Cooperative Institutions

National Taiwan University

University of Chemistry and Technology, Prague

Academia Sinica

National Yang Ming Chiao Tung University

Centre National de la Recherche Scientifique

National Taiwan University of Science and Technology

Institut National de Physique Nucléaire et de Physique des Particules

Advanced Materials and Processes Research Institute

Academy of Scientific and Innovative Research

Université Paris Cité

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Field

Ultralow Threshold Cavity-Free Laser Induced by Total Internal Reflection

ACS Omega (2020)

Han‐Wen Hu Golam Haider Yu‐Ming Liao Pradip Kumar Roy Hung‐I Lin

Total internal reflection is one of the most important phenomena when a propagated wave strikes a medium boundary, which possesses a wide range of applications spanning from optical communication to a fluorescence microscope. It has also been widely used to demonstrate conventional laser actions with resonant cavities. Recently, cavity-free stimulated emission of radiation has attracted great attention in disordered media because of several exciting physical phenomena, ranging from Anderson localization of light to speckle-free imaging. However, unlike conventional laser systems, the total internal reflection has never been implemented in the study of laser actions derived from randomly distributed media. Herein, we demonstrate an ultra-low threshold cavity-free laser system using air bubbles as scattering centers in which the total internal reflection from the surface of air bubbles can greatly reduce the leakage of the scattered beam energy and then enhance light amplification within a coherent closed loop. Our approach provides an excellent alternative for the manipulation of optical energy flow to achieve ultra-low threshold cavity-free laser systems, which should be very useful for the development of high performance optoelectronic devices.

Reflection

Optical cavity

10.1021/acsomega.9b04094

Cite

Citations (5)

Emerging pnictogen-based 2D semiconductors: sensing and electronic devices

Nanoscale (2020)

Pradip Kumar Roy Jan Luxa Zdeněk Sofer

Pnictogens are an intensively studied group of monoelemental two-dimensional materials. This group of elements consists of phosphorus, arsenic, antimony, and bismuth. In this group, the elements adopt two different layered structural allotropes, orthorhombic structure with true van der Waals layered interactions and rhombohedral structure, where covalent interactions between layers are also present. The orthorhombic structure is well known for phosphorus and arsenic, and the rhombohedral structure is the most thermodynamically stable allotropic modification of arsenic, antimony, and bismuth. Due to the electronic structure of pnictogen layers and their semiconducting character, these materials have huge application potential for electronic devices such as transistors and sensors including photosensitive devices as well as gas and electrochemical sensors. While photodetection and gas sensing applications are often related to lithography processed materials, chemical sensing proceeds in a liquid environment (either aqueous or non-aqueous) and can be influenced by surface oxidation of these materials. In this review, we explore the current state of pnictogen applications in sensing and electronic devices including transistors, photodetectors, gas sensors, and chemical/electrochemical sensors.

Pnictogen

Bismuth

Orthorhombic crystal system

Exfoliation joint

10.1039/d0nr02932g

Cite

Citations (27)

A plasmon-tuned ‘gold sandwich’ for metal enhanced fluorescence in silica coated NaYF₄:Yb,Er upconversion nanoparticles

RSC Advances (2016)

Robeth Viktoria Manurung Chien‐Ting Wu Pradip Kumar Roy Surojit Chattopadhyay

The low quantum yield of luminescence from lanthanide-doped up-conversion nanoparticles (UCNPs) has been enhanced by using an optimized 'gold sandwich' with a transparent top layer and a reflecting bottom layer at 980 nm excitation. Erbium (Er)-doped UCNPs, with a NaYF4:Yb,Er core, were synthesized by a thermal decomposition process and coated with silica to assist in metal-enhanced fluorescence (MEF). A bottom layer of thick coalesced gold island film, acting as a mirror, increases the optical path length of the 980 nm radiation through the UCNP layer dispersed on it. This layer enhances the UCNPs' 540 nm green emission by a factor of 5–8 compared to that in the absence of the gold reflector. A thin nanoparticle-like gold layer on top of the UCNPs, with a surface plasmon absorption around ∼550 nm, completes the sandwich, which augments the luminescence enhancement by another factor of ∼2.5, thus taking the net enhancement factor to ∼13–19 when compared to the luminescence in the absence of the gold-sandwich. The surface plasmon absorption in the top gold layer enhances the local electric field at the UCNPs to promote their radiative decay. Compared to previous reports, mostly for the solution state, the current case study is a solid state measurement.

10.1039/c6ra20273j

Cite

Citations (19)

Energy loss due to field fluctuations in a two-stream QCD plasma

arXiv (Cornell University) (2011)

Mahatsab Mandal Abhee K. Dutt-Mazumder Pradip Kumar Roy Sreemoyee Sarkar

We derive the expression for the collisional energy loss in two stream plasma induced by the fluctuating chromoelectric field. It is revealed that the main contribution here comes from the unstable modes which grow exponentially with time. A strong direction dependence of the energy loss has also been demonstrated.

10.48550/arxiv.1109.1181

Cite

Citations (0)

THE FREJUS NUCLEON DECAY EXPERIMENT

B. Degrange Christoph Berger K.-H. Becker P. Bareyre U. Nguyen-Khac

Source

Cite

Citations (0)

Photocatalytic Activity of Twist-Angle Stacked 2D TaS2

Evgeniya Kovalska Pradip Kumar Roy Nikolas Antonatos Vlastimil Mazánek Martin Veselý

The development of low-cost efficient photoelectrosensitive electrodes as an alternative to the expensive and complex rigid systems is yet in huge demand for advanced photoresponsive technology. Herein, the light-induced efficiency of electrochemically exfoliated TaS2 nanosheets for hydrogen generation catalysis and photodetectors has been demonstrated for the first time. The electrochemical exfoliation of TaS2 crystals toward a few-layer derivative has been pioneered in anhydrous tetrabutylammonium hexafluorophosphate in N, N-dimethylformamide. Comprehensive analysis of as-exfoliated TaS2 revealed the formation of nanoparticles and nanosheets with a lateral size of about several nanometers and micrometers, correspondingly. Observed mutual twisting of 2H-TaS2 flakes leads to the redistribution of charge density induced by interlayer interaction of the individual nanosheets. External light irradiation on the TaS2 surface influences its conductivity making the material feasible for photoelectrocatalysis and photodetection. The TaS2-based catalyst demonstrates high HER photoelectrocatalytic activity with the onset overpotential below 575 mV vs. RHE which can be lowered by thorough catalyst preparation. Finally, the TaS2-integrated photodetector in the acidic medium represents its broadband light sensing capability with the highest photoresponsivity (0.68 mA W-1 ) toward 420 nm light illumination. This finding will pave the way to a new realization of exfoliated twist-angle stacked TaS2 for photo-induced electrochemistry and sensing

Overpotential

Photodetection

Exfoliation joint

Nanometre

10.26434/chemrxiv.14153675

Cite

Citations (0)

Chalcogen (S, Se, and Te) decorated few-layered Ti₃C₂T_x MXene hybrids: modulation of properties through covalent bonding

Nanoscale (2023)

Jalal Azadmanjiri Pradip Kumar Roy Lukáš Děkanovský Zdeněk Sofer

2D carbides and nitrides of transition metals (MXenes) have shown great promise in a variety of energy storage and energy conversion applications.

MXenes

Chalcogen

10.1039/d2nr05730a

Cite

Citations (9)

A Highly-Efficient Single Segment White Random Laser

ACS Nano (2018)

Golam Haider Hung‐I Lin Kanchan Yadav Kun‐Ching Shen Yu‐Ming Liao

Production of multicolor or multiple wavelength lasers over the full visible-color spectrum from a single chip device has widespread applications, such as superbright solid-state lighting, color laser displays, light-based version of Wi-Fi (Li-Fi), and bioimaging, etc. However, designing such lasing devices remains a challenging issue owing to the material requirements for producing multicolor emissions and sophisticated design for producing laser action. Here we demonstrate a simple design and highly efficient single segment white random laser based on solution-processed NaYF4:Yb/Er/Tm@NaYF4:Eu core-shell nanoparticles assisted by Au/MoO3 multilayer hyperbolic meta-materials. The multicolor lasing emitted from core-shell nanoparticles covering the red, green, and blue, simultaneously, can be greatly enhanced by the high photonic density of states with a suitable design of hyperbolic meta-materials, which enables decreasing the energy consumption of photon propagation. As a result, the energy upconversion emission is enhanced by ∼50 times with a drastic reduction of the lasing threshold. The multiple scatterings arising from the inherent nature of the disordered nanoparticle matrix provide a convenient way for the formation of closed feedback loops, which is beneficial for the coherent laser action. The experimental results were supported by the electromagnetic simulations derived from the finite-difference time-domain (FDTD) method. The approach shown here can greatly simplify the design of laser structures with color-tunable emissions, which can be extended to many other material systems. Together with the characteristics of angle free laser action, our device provides a promising solution toward the realization of many laser-based practical applications.

10.1021/acsnano.8b03035

Cite

Citations (60)

Detection of melamine on fractals of unmodified gold nanoparticles by surface-enhanced Raman scattering

Journal of Biomedical Optics (2013)

Pradip Kumar Roy Yifan Huang Surojit Chattopadhyay

A simple way of detecting melamine in raw milk is demonstrated via surface-enhanced Raman spectroscopy (SERS) using fractals of bare and nonfunctionalized ∼30 nm gold nanoparticles (AuNP) distributed on a solid support. The technique demonstrates the formation of AuNP fractals, from a random distribution, upon exposure to melamine, that enhance the Raman scattering cross-section to enable detection by SERS. The agglomeration, which is pronounced at higher melamine concentrations, is demonstrated directly through imaging, and the red-shift of the plasmon absorption peak of the AuNP fractal away from 530 nm by finite difference time domain (FDTD) calculations. The agglomeration results in a strong plasmon field, shown by FDTD, over the interparticle sites that enhances the Raman scattering cross-section of melamine and ensures unambiguous detection. Limit of detection of 100 ppb could be achieved reproducibly.

Surface-Enhanced Raman Spectroscopy

10.1117/1.jbo.19.1.011002

Cite

Citations (21)

Single-Step Synthesis of Platinoid-Decorated Phosphorene: Perspectives for Catalysis, Gas Sensing, and Energy Storage

ACS Applied Materials & Interfaces (2020)

Evgeniya Kovalska Jan Luxa Manuel Melle‐Franco Bing Wu Marek Ivo

The originality of phosphorene is suppressed by its structural defects, irreproducibility, and sensitivity to the ambient environment. To preserve phosphorene's essential characteristics, for example, influencing the charge redistribution and generating the formation of active centers, noble-metal decoration is found to be an efficient approach. Herein, we demonstrate a single-step electrochemical synthesis of platinoid-decorated few-layer phosphorene (FP). The material's structure and effects of metal (Ru, Rh, and Pd) deposition on the FP nanosheets were first explored by numerous analytical techniques and theoretical calculations. Platinoid-decorated FPs demonstrate high quality and consist of one to five layers modified with round- and heptagon-shaped metal nanoparticles with the most intense distribution of Pd. The high-rate Rh deposition provides the enhanced electrocatalytic efficiency for hydrogen evolution (79 mV·dec-1-Tafel slope) and almost 20 times increased capacity for the Li-ion batteries in comparison to bare and Ru-decorated FP. The chemosensing of platinoid-decorated FP indicates a response to methanol plus ethanol and shows inertness to acetone. The incorporation of Ru and Rh nanoparticles increases FP's selectivity toward methanol. This research provides a new approach for the in situ FP functionalization during top-down synthesis and thus broadens the material's feasibility for advanced nanotechnology.

Phosphorene

10.1021/acsami.0c15525

Cite

Citations (20)