Chemistry Graduate and Undergraduate Professor
E-mail: brad.weiner@upr.edu ; brad@hpcf.upr.edu
Office: FB-304 ; MSRC 240
Laboratory: FB-146 ; FB-147 ; MSRC 207
Research Interests
Physical Chemistry: Gas Phase Molecular Reaction Dynamics; Laser Photochemistry and Photophysics; Gas Phase Kinetics of Reactive Intermediates; Nanoscience, Biomedical Applications of Nanotechnology.
Research
The detailed mechanisms of elementary unimolecular and bimolecular reactions are not well understood. In part, the problem lies in the difficulty of monitoring the evolution of highly reactive, short-lived intermediates during the course of the reaction. Our research applies a host of modern spectroscopic (primarily laser-based) techniques to understand the structure and reactivity of said transient species in the gas phase. In recent years, this research has focused on the chemistry of gas phase sulfur-containing species.
These studies have important overlap with current theoretical problems and are also relevant to the chemistry of high-energy gas phase environments, such as the upper and lower atmosphere, and combustion systems. Another area of interest in our research program is the development of new techniques and methodology for the detection of reactive intermediates. In particular, multiphoton processes are being investigated as a new means of probing polyatomic molecules of real world interest. Applications to atmospheric systems and microelectronic device fabrication are being explored.
Publications
Recent Publications (last 5 years)
Sandra Rodríguez-Villanueva, Frank Mendoza, Alvaro A. Instan, Ram S. Katiyar, Brad R. Weiner and Gerardo Morell, “Graphene Growth directly on SiO2/Si by Hot Filament Chemical Vapor Deposition”Nanomaterials, 2022, 12(1): 109. DOI: 10.3390/nano12010109
Shyam Sutariya, Olesia Gololobova, Mohammed Bsatee, Daysi Diaz-Diestra, Bibek Thapa, Brad R. Weiner, Gerardo Morell, Wojciech Jadwisienczak, and Juan Beltran-Huarac, “Magnetic Control of the Mn Photoluminescence in Fe3O4/L-cys ZnS:Mn Nanocomposites”, ACS Omega, 2021, 6, 7598-7604. DOI: 10.1021/acsomega.0c06164
Rajesh K. Katiyar, Balram Tripathi, Javier Palomino, Atul Tiwari, Shiva Adireddy, Ambesh Dixit, Brad R Weiner, Gerardo Morell and Ram S Katiyar, “Graphene Modulated LiMn1.5Ni0.4Cr0.1O4 Spinel Cathode for Lithium Ion Batteries”, Nano Express 2020, 1, 020028. DOI: 10.1088/2632-959X/abadda
Khaled Habiba, Kathryn Aziz, Keith Sanders, Carlene Michelle Santiago, Lakshmi Shree Kulumani Mahadevan, Vladimir Makarov, Brad R. Weiner, Gerardo Morell, and Sunil Krishnan, “Enhancing Colorectal Cancer Radiation Therapy Efficacy using Silver Nanoprisms Decorated with Graphene as Radiosensitizers” Scientific Reports 2019, 9: 17120. DOI: 10.1038/s41598-019-53706-0
Muhammad Sajjad, Vladimir Makarov, Frank Mendoza, Muhammad S.Sultan, Ali Aldalbahi, Peter X. Feng, Wojciech M. Jadwisienczak, Brad R. Weiner and Gerardo Morell, “Synthesis, Characterization and Fabrication of Graphene/Boron Nitride Nanosheets Heterostructure Tunneling Devices”, Nanomaterials 2019, 9, 925; DOI:10.3390/nano9070925
Bibek Thapa, Daysi Diaz-Diestra, Dayra Badillo-Diaz, Rohit Kumar Sharma, Kiran Dasari, Shalini Kumari, Mikel B. Holcomb, Juan Beltran-Huarac, Brad R. Weiner and Gerardo Morell, “Controlling the Transverse Proton Relaxivity of Magnetic Graphene Oxide”, Scientific Reports 2019, 9: 5633. DOI: 10.1038/s41598-019-42093-1
Daysi Diaz-Diestra, Bibek Thapa, Juan Beltran-Huarac, Gerardo Morell and Brad R. Weiner, “Graphene Oxide/ZnS:Mn Nanocomposite Functionalized with Folic Acid as a Nontoxic and Effective Theranostic Platform for Breast Cancer Treatment”, Nanomaterials, 2018, 8, 484. DOI:10.3390/nano8070484
Bibek Thapa, Carlene Santiago, Dayra Badillo, Emmanual Morales, Kevin Martinez, Daysi Diaz-Diestra, Nitu Kumar, Kaixiong Tu, Juan Beltran-Huarac, Brad R. Weiner and Gerardo Morell, “T1– and T2-weighted Magnetic Resonance Dual Contrast by Single Core Iron Oxide Nanoparticles with Abrupt Cellular Internalization and Immune Evasion”, ACS Appl. Bio Mater. 2018, 1, 79−89. DOI: 10.1021/acsabm.8b00016
Muhammad Sajjad, Vladimir I. Makarov, M. S. Sultan, W. M. Jadwisienczak, Brad R. Weiner, and Gerardo Morell, “Synthesis, Optical and Magnetic Properties of Graphene Quantum Dots and Iron Oxide Nanocomposites”, 2018 Advances in Materials Science and Engineering, 3254081. DOI: 10.1155/2018/3254081
Sita Dugu, Shojan P. Pavunny, Tej B. Limbu, Brad R. Weiner, Gerardo Morell and Ram S. Katiyar, “A Graphene Integrated Highly Transparent Resistive Switching Memory Device”, 2018 APL Materials, 6, 058503. DOI: 10.1063/1.5021099
Tej B. Limbu, Jean C. Hernández, Frank Mendoza, Rajesh K. Katiyar, Joshua James Razink, Vladimir I. Makarov, Brad R. Weiner, and Gerardo Morell, “A Novel Approach to the Layer Number-controlled and Grain Size-controlled Growth of High Quality Graphene”, 2018 ACS Appl. Nano Mater., 1 (4), pp 1502–1512. DOI: 10.1021/acsanm.7b00410
Tej B. Limbu, K.R. Hahn, Frank Mendoza, S. Sahoo, Joshua James Razink, Ram S. Katiyar, Brad R. Weiner and G. Morell, “Grain Size-dependent Thermal Conductivity of Polycrystalline Twisted Bilayer Graphene”, 2017 Carbon 117, 367. DOI: 10.1016/j.carbon.2017.02.066.
Daysi Diaz-Diestra, Bibek Thapa, Juan Beltran-Huarac, Brad R. Weiner and Gerardo Morell, “L-cysteine Capped ZnS:Mn Quantum Dots for Room-Temperature Detection of Dopamine with High Sensitivity and Selectivity”, 2017 Biosensors and Bioelectronics, 87(15), 693-700. DOI: 10.1016/j.bios.2016.09.022
Bibek Thapa, Daysi Diaz-Diestra, Juan Beltran-Huarac, Huadong Zeng, Joanna Long, Brad R. Weiner and Gerardo Morell, “Enhanced MRI T2 Relaxivity in Contrast-Probed Anchor-free PEGylated Iron Oxide Nanoparticles”, 2017 Nanoscale Research Letters 12:312. DOI: 10.1186/s11671-017-2084-y
S. Gupta, B. R. Weiner and G. Morell, Ex situ spectroscopic ellipsometry investigations of chemical vapor deposited nanocomposite carbon thin films, Thin Solid Films, 455, 422-428 (2004).
S. Gupta, G. Morell and B. R. Weiner, Electron field-emission mechanism in nanostructured carbon films: a quest, J. Appl. Phys., 95, 8314-8320 (2004).
S. Gupta, G. Morell and B. R. Weiner, Role of H in hot-wire deposited a-Si:H films revisited: optical characterization and modeling, J. Non-Cryst. Solids, 343, 131-142 (2004).
S. Gupta, B. R. Weiner, W. H. Nelson and G. Morell, Ultraviolet and visible Raman spectroscopic investigations of nanocrystalline carbon thin films grown by bias-assisted hot-filament chemical vapor deposition, J. Raman Spectrosc., 34, 192-198 (2003).
Feng, P.X. and Brad R. Weiner, High Abundance of Metastable Helium Atoms for Diagnostic Applications, J. Phys. B: At., Mol. Opt. Phys., 37, 1-5 (2004).
Adolfo Gonzalez-Berrios, Dachun Huang, Nadia M. Medina-Emmanuelli, Kathleen E. Kristian, Oscar O. Ortiz, Juan A. Gonzalez, Joel De Jesus, Iris M. Vargas, Brad R. Weiner and Gerardo Morell, Effects of heavy-ion radiation on the electron field emission properties of sulfur-doped nanocomposite carbon films, Diamond Relat. Mater., 13, 221-225 (2004).
S. Gupta, B. R. Weiner and G. Morell, Influence of sulfur incorporation on field-emission properties of microcrystalline diamond thin films, J. Mater. Res., 18, 2708-2716 (2003).
Kathleen E. Kristian, Nadia M. Medina-Emmanuelli, Oscar O. Ortiz, Adolfo Gonzalez, Juan A. Gonzalez, Joel De Jesus, Iris M. Vargas, Brad R. Weiner and Gerardo Morell, Study of the effects of heavy-ion radiation on nanocomposite carbon films, Mater. Res. Soc. Symp. Proc., 777, 189-194 (2003).
Joel De Jesus, Juan A. Gonzalez, Oscar O. Ortiz, Brad R. Weiner and Gerardo Morell, Parallel bias-enhanced sulfur-assisted chemical vapor deposition of nanocrystalline diamond films, Mater. Res. Soc. Symp. Proc., 775, 325-330 (2003).
F. A. M. Kock, J. M. Garguilo, R. J. Nemanich, S. Gupta, B. R. Weiner and G. Morell, Spatial distribution of electron emission sites for sulfur doped and intrinsic nanocrystalline diamond films, Diamond Relat. Mater., 12, 474-480 (2003).
Yuchuan Gong, Vladimir I. Makarov and Brad R. Weiner, Time-resolved Fourier transform infrared study of the 193 nm photolysis of SO 2, Chem. Phys. Lett., 378, 493-502 (2003).
S. Gupta, B. R. Weiner and G. Morell, Synthesis and characterization of sulfur-incorporated microcrystalline diamond and nanocrystalline carbon thin films by hot filament chemical vapor deposition, J. Mater. Res., 18, 363-381 (2003).
S. Gupta, B. R. Weiner and G. Morell, Room-temperature electrical conductivity studies of sulfur-modified microcrystalline diamond thin films, Appl. Phys. Lett., 83, 491-493 (2003).
Joel De Jesus, Juan A. Gonzalez, Brad R. Weiner, and Gerardo Morell, Studies of Doped Nanocrystalline Diamond Films Grown by Parallel Bias-enhanced Chemical Vapor Deposition, IEEE Nano 2003 Conference Proceedings, 2, 480 (2003).