Research Activities @MagRes
Our group’s research focuses on developing new protocols, methods and tools for quantum sensing and magnetic resonance and their applications to various systems some of which are listed below.
Tools and Instrumentation
Pharmaceutical Compounds and Biomolecules
Sustainable Construction Materials
The global construction industry is actively seeking sustainable, low-carbon alternatives to Portland cement to combat massive CO2 emissions. This has led to the development and optimization of novel cementitious materials, such as Alkali-Activated Binders (AABs). The crucial challenge lies in guaranteeing that these new materials match or exceed the performance of traditional concrete, particularly regarding strength, long-term durability etc.
Characterizing the microstructure of cementitious materials is inherently difficult because the binding phases are disordered, amorphous, and often coexists with multiple other phases. Solid-state NMR can provide the key structural details by probing the local electronic environments of key nuclear spins (29Si, 27Al, 23Na, 1H, 43Ca etc.) in these materials. This allows us to quantify the degree of polymerization (chain length) of the silicate structure and the role of Al, which are key determinants of material strength. Thus role of NMR becomes crucial in understanding the critical structural evolution of processes like accelerated carbonation, hydration of cements etc.
Study of solid elctrolyte materials using NMR
Energy storage devices (ESDs) with high safety, long durability, low cost, high energy, and power density are absolutely necessary to replace fossil fuels with renewable energy and combat one of the greatest threats to the planet: climate change. Currently, lithium-ion batteries (LIBs) are the most common ESDs. However, the problems of flammability, dendritic growth, low energy density, and limited operating temperature range limit their usage to a small scale.
LIBs with solid electrolytes (SEs) are promising alternatives to address the problems above, but there are two major challenges with those: (i) High resistance at the electrode-electrolyte (solid-solid) interface and (ii) low ionic conductivity in the SEs. We will use solid-state NMR that is not restricted by these obstacles and can directly probe the key elements such as 1H, 7Li, 13C, 14N, 19F, etc., frequently present in the solid electrolyte material.
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Our aim is to improve the sensitivity by developing specific NMR pulse sequences targeting battery materials and using hyperpolarization methods that allow a sensitivity boost by two orders of magnitude. We will merge the expertise in NMR instrumentation, pulse sequence development, and cell design for in-situ battery studies to gain deeper insight into the interactions at the interface as well as in the electrolyte that determine the efficiency of the battery.
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Quantum Enhanced Magnetic Resonance and Sensing
Dynamic Nuclear Polarization (DNP) alleviates the sensitivity problem of Nuclear Magnetic Resonance (NMR) by transferring the spin polarization of the relatively more sensitive electron spins (e) to the nuclear spins (n) of interest. DNP requires paramagnetic centers, either intrinsic to the system or added extrinsically, coupled with the nuclear spins and microwave irradiation near EPR frequencies of the paramagnetic centers to drive the polarization transfer. The most commonly employed DNP experiments are performed at ~100K using gyrotrons as high-power microwave sources. Several DNP mechanisms, like the Overhauser Effect, Solid Effect, Cross Effect, etc., are used for several systems depending upon experimental conditions like the field, microwave power, EPR properties, and radicals. However, the need for cryogenic temperatures to combat fast electron spin relaxation rates restricts the applicability of DNP. Moreover, the high cost of gyrotrons, high maintenance, and facility requirements make it a highly specialized equipment limited to few labs.
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The paramagnetic diamond defects, including the NV-centers, are promising alternatives to the conventional radical-based polarizing agents due to their relatively longer coherence times at room temperature. Our approach is to design a DNP mechanism effective over a longer e-n distance, using microwave pulses and coupled electron spin systems (NV-NV, NV-P1, or NV-external electron spins) rather than isolated defect centers.​​​​​​​​​​
Relaxation Theory in MR
The dynamics of spin systems have been one of the most interesting topics from the beginning of the Quantum age. Theoretical explanations along with magnetic resonance experiments are the latest way to explore the spin dynamics of various systems in Material research, Biology, Quantum materials, etc. Now relaxation of spins can be a friend but also be a foe in both EPR and NMR spectroscopy. Our aim is to understand relaxations and prescribing new techniques in magnetic resonance spectroscopy. Also, the effect of paramagnetic centers on spin dynamics is aimed to describe with theoretical prescriptions.
Different interactions are always a part of magnetic resonance spectroscopy. We are focused on making new RF pulses for decoupling and enhancing the sensitivity for the information of interest.
NMR Theory and Methods
New RF pulse sequences and NMR crystallography
Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy is a vital tool for probing the structure, dynamics, and interactions of molecules in solid materials. Despite significant advancements, the field continues to explore innovative spin-probing techniques to selectively excite or suppress specific spin-spin interactions, with a particular emphasis on improving the measurement of molecular dynamics. These efforts aim to enhance the resolution and sensitivity of NMR experiments, enabling detailed characterization of complex materials such as amorphous systems, polymers, and biomolecules.
The MagRes research group is at the forefront of these advancements, focusing on the development of novel radiofrequency (RF) pulse sequences through optimal control theory.
