Rapid and precise determination of zero-field splittings by terahertz time-domain electron paramagnetic resonance spectroscopy

Abstract

Single-cycle THz fields induce free-induction decays from high-spin transition-metal complexes, yielding THz EPR spectra and zero-field splitting parameters from a simple tabletop measurement.

A Trigonal Prismatic Cobalt(II) Complex as a Single Molecule Magnet with a Reduced Contribution from Quantum Tunneling

“…At conventional frequencies, they are almost always EPR-silent, as the transition M S = À S↔ + S is forbidden by the selection rules for large S, and high-lying M S = � 1/2 Kramer's doublet is unpopulated. At extremely high frequencies, however, THz-EPR spectroscopy can access the inter-Kramer's transition M S = � S↔ � (SÀ 1) and therefore directly measure the ZFS value, [23][24][25][26][27][28] which is the key characteristic of an SMM related to the energy U of the magnetization reversal barrier U = 2|D| with D being a zero-field splitting energy.…”

Broadband Tunable Electron Paramagnetic Resonance Spectroscopy of Dilute Metal Complexes

“…1 GHz) to the J-band (ca. 263 GHz), and outside this range machines have been laboratory-built for subgigahertz 19 to terahertz 20 frequencies. In spite of these developments, multifrequency EPR has not become a routine practice in the study of transition ion complexes, presumably due to the excessive cost of investment and operational complexity.…”

Two-Dimensional Spectroscopy at Terahertz Frequencies

“…The methodology is expected to be applicable to the study of many chemical and biological systems with spin resonances at THz frequencies. To date, linear THz-frequency EPR spectroscopy has been conducted based on THz time-domain spectroscopy [94,95], coherent synchrotron radiation [96] or blackbody radiation [97,98]. These studies have measured the ZFSs in single-molecule magnets [95,96] and other molecular and biological systems [95,99,100] at zero and nonzero external magnetic field.…”

“…To date, linear THz-frequency EPR spectroscopy has been conducted based on THz time-domain spectroscopy [94,95], coherent synchrotron radiation [96] or blackbody radiation [97,98]. These studies have measured the ZFSs in single-molecule magnets [95,96] and other molecular and biological systems [95,99,100] at zero and nonzero external magnetic field. We anticipate that 2D EPR spectroscopy of molecular complexes and biomolecules in the THz frequency range will be demonstrated and will provide wide-ranging new insights just as it has in lower frequencies.…”