Application of pulsed heating in time-resolved EPR spectroscopy for longitudinal relaxation measurements

Application of pulsed heating in time-resolved EPR spectroscopy for longitudinal relaxation measurements Full article

Journal

The Journal of Chemical Physics
ISSN: 0021-9606

Output data

Year: 2025, Volume: 163, Number: 16, Article number : 164201, Pages count : 16 DOI: 10.1063/5.0291635

Authors

Melnikov Anatoly R. ¹ , Maryasov Alexander G. ² , Ishchenko Anastasia S. ^1,3 , Getmanov Yaroslav V. ⁴ , Isaev Nikolay P. ⁵ , Efimov Nikolay N. ⁶ , Fedin Matvey V. ¹ , Veber Sergey L. ¹

Affiliations

1	International Tomography Center of the Siberian Branch of the Russian Academy of Sciences, 3a, Institutskaya Str., Novosibirsk 630090, Russian Federation
2	Vorozhtsov Novosibirsk Institute of Organic Chemistry of the Siberian Branch of the Russian Academy of Sciences, 9, Acad. Lavrentieva Ave., Novosibirsk 630090, Russian Federation
3	Novosibirsk State University, 1, Pirogova Str., Novosibirsk 630090, Russian Federation
4	Budker Institute of Nuclear Physics of the Siberian Branch of the Russian Academy of Sciences, 11, Acad. Lavrentieva Ave., Novosibirsk 630090, Russian Federation
5	Voevodsky Institute of Chemical Kinetics and Combustion of the Siberian Branch of the Russian Academy of Sciences, 3, Institutskaya Str., Novosibirsk 630090, Russian Federation
6	Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, 31, Leninsky Ave., Moscow 119991, Russian Federation

Transient or time-resolved electron paramagnetic resonance spectroscopy (TR EPR) is a powerful method for studying various photogenerated paramagnetic species. The use of low-energy quanta, such as terahertz (THz) radiation, as an external stimulus in TR EPR allows the initiation of spin dynamics without generating new paramagnetic species other than those already present in the system. This spin dynamic reflects the return of the system to thermodynamic equilibrium, governed by a spin–lattice relaxation time, T1. The latter, together with a phase memory time, is of paramount importance for the practical implementation of single-molecule magnets and molecular spin qubits. In this work, we present TR EPR spectroscopy with pulsed heating by THz pulses as a versatile spectroscopic method for determining T1 in a wide range of paramagnetic systems. To define the scope of the method, we developed a numerical model based on the Liouville–von Neumann equation, with the equilibrium density matrix defined by the temperature profile of the lattice. Using experimental data obtained for [CoTp2] (cobalt(II) bis[tris(pyrazolyl)borate]) with S = 3/2, we compared the proposed method with two other commonly used techniques: alternating current (AC) magnetometry and pulsed EPR. All three methods were found to be in qualitative agreement and provided complementary information about the relaxation properties. TR EPR spectroscopy showed the orientation dependence of T1. AC magnetometry revealed the dependence of T1 on the value of the external magnetic field, which was attributed in the literature to a field-induced Raman process. Finally, pulsed EPR spectroscopy was found to be biased by strong spectral diffusion.

Melnikov A.R. , Maryasov A.G. , Ishchenko A.S. , Getmanov Y.V. , Isaev N.P. , Efimov N.N. , Fedin M.V. , Veber S.L.
Application of pulsed heating in time-resolved EPR spectroscopy for longitudinal relaxation measurements
The Journal of Chemical Physics. 2025. V.163. N16. 164201 :1-16. DOI: 10.1063/5.0291635 WOS Scopus OpenAlex

Submitted:	Jul 18, 2025
Accepted:	Oct 7, 2025
Published print:	Oct 28, 2025

Web of science:	WOS:001600274200002
Scopus:	2-s2.0-105019502664
OpenAlex:	W4415466608

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