19 Jan 2019
Kong's paper was published in Science Advances yesterday: Time-Optimized Pulsed Dynamic Nuclear Polarization. The paper reports a new DNP pulse sequence, named TOP DNP. The matching condition for electron-1H polarization transfer in TOP DNP does not depend on the microwave amplitude directly, but instead relies on the timing in a train of microwave pulses. The sequence is a major step towards the implementation of pulsed DNP in high-resolution MAS NMR.
24 Sep 2018
Janne's paper is now available on the website of PCCP: Conformation of Bis-nitroxide Polarizing Agents by Multi-frequency EPR Spectroscopy. The paper shows that EPR spectroscopy can be used to determine the conformation of a biradical while it is in the frozen-glassy matrix that is used in DNP/MAS NMR experiments. Since this conformation strongly affects the DNP efficiency, the results are highly important as a guide for the design and synthesis of future polarizing agents.
19 Feb 2018
Dr. R. Venkata SubbaRao joins the lab from India. Welcome Rao!
10 Oct 2017
My paper with Sheetal has been accepted by The Journal of Chemical Physics: Off-resonance NOVEL. The paper describes a modification of the DNP pulse sequence NOVEL with a reduced microwave power requirement. It hereby opens up a path for the implementation of pulsed DNP in high-resolution MAS NMR. The paper also explores the use of average Hamiltonian theory to describe polarization transfer from electrons to bulk 1H.
1 Oct 2017
Our paper with the group of Gaël de Paëpe in Grenoble is now online. Chemical Science: Efficient cross-effect dynamic nuclear polarization without depolarization in high-resolution MAS NMR. Compared to their bis-nitroxide counterparts, the use of heterogeneous biradicals, like TEMTriPol, as polarizing agents for DNP makes it possible circumvent the detrimental depolarization effect, which depletes the initial nuclear Boltzmann polarization by more than a factor of 2. Experimental data on the DNP performance of TEMTriPol is combined with numerical simulations of cross-effect DNP/MAS NMR to gain a physical understanding of the absence of depolarization in TEMTriPol. The tremendous gain in sensitivity is illustrated with the overnight recording of a 13C-13C correlation spectrum of natural abundance cellulose at 800 MHz.
30 Jun 2017
The refurbished RF amplifier from E&I, NY made it safely through customs. Time to do some DNP!