An EPR method for probing surface magnetic fields, dipolar distances, and magnetization fluctuations in single molecule magnets

B Rakvin; D Zilić; N S Dalal; J M North; P Cevc; D Arcon; K Zadro

doi:10.1016/j.saa.2003.10.022

An EPR method for probing surface magnetic fields, dipolar distances, and magnetization fluctuations in single molecule magnets

Spectrochim Acta A Mol Biomol Spectrosc. 2004 May;60(6):1241-5. doi: 10.1016/j.saa.2003.10.022.

Authors

B Rakvin¹, D Zilić, N S Dalal, J M North, P Cevc, D Arcon, K Zadro

Affiliation

¹ Department of Physical Chemistry, Ruder Bosković Institute, Bijenicka 54, P.O. Box 180, Zagreb 10002, Croatia. rakvin@irb.hr

PMID: 15134721
DOI: 10.1016/j.saa.2003.10.022

Abstract

We outline a spectroscopic method for probing the effective magnetic field B on the surface of crystals of the single molecule magnet (SMM) [(C6H15N3)6Fe8(mu3-O)2(mu2-OH)12]Br7(H2O)Br.H2O, (Fe8Br8). This technique utilizes the line shape changes in the EPR spectra of the organic radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) (g = 2.0036, single peak) adsorbed onto the sample. The temperature dependence of the EPR line shifts scale with the sample's magnetization as measured by a SQUID magnetometer. Analysis of the line shape in terms of dipolar coupling between the DPPH and the SMM molecules on the surface, yields their average dipolar distance. The method's potential for measuring the magnetization fluctuation dynamics is briefly pointed out using the SMM [Mn12O12(CH3COO)16(H2O)4].2CH3COOH.4H2O (Mn12-acetate).

MeSH terms

Adsorption
Biphenyl Compounds / chemistry
Electron Spin Resonance Spectroscopy / methods*
Hydrazines / chemistry
Iron Compounds / pharmacokinetics
Magnetics*
Manganese / chemistry
Picrates
Surface Properties
Temperature

Substances

Biphenyl Compounds
Hydrazines
Iron Compounds
Picrates
Manganese
1,1-diphenyl-2-picrylhydrazyl