New England Section Fall 2022 Meeting
Volume 67, Number 13
Friday–Saturday, October 14–15, 2022;
University of New Hampshire, Durham, NH
Session G02: Parallel Invited Session - Nuclear Physics II
8:30 AM–9:42 AM,
Saturday, October 15, 2022
University of New Hampshire in Durham
Room: DeMeritt Hall 240
Chair: David Ruth
Abstract: G02.00002 : Instrumentation for High- and Low-Field/High-Frequency DNP/EPR Spectroscopy
9:06 AM–9:42 AM
Abstract
Presenter:
Thorsten Maly
(Bridge12 Technologies)
Author:
Thorsten Maly
(Bridge12 Technologies)
Dynamic Nuclear Polarization (DNP) is a technique in which the large thermal electron polarization is transferred to the nuclear spin reservoir by saturation of an allowed or forbidden Electron Paramagnetic Resonance (EPR) transition. The technique can provide a sensitivity boost in some cases close to the theoretical maximum of 660 (for 1H). In recent years, DNP has proven to be a robust method to increase signal intensities in NMR experiments in laboratories around the world The efficiency of the DNP process in solids or solutions depends on many different factors such as the strength of the magnetic field at which the experiment is performed, the strength of the microwave induced magnetic field (w1e), or the electron T1e and T2e relaxation times. Furthermore, in the case of solid-state DNP spectroscopy, the strength of the electron dipolar coupling in a biradical and the breadth of the EPR spectrum (D) are important factors to know to understand the type of DNP mechanism and to optimize its performance. It is therefore crucial to understand the EPR spectrum and relaxation properties of the polarizing agent at the same magnetic field at which the DNP experiment is performed. Low-field DNP spectroscopy, in particular Overhauser DNP spectroscopy is a powerful tool to study hydration dynamics at liquid/solid interfaces. Here, the instrumentation requirements are less demanding and microwave cavities with integrated RF coils are commonly employed. High-field DNP spectroscopy, on the other hand, presents many different challenges. Due to their microscopic sizes, cavities are less frequently used. In addition, the maximum available microwave/THz power is severely limited, and many low-frequency discreet microwave components do not have an equivalent at high frequencies and quasi-optical methods must be used.