title: An EPR method for probing surface magnetic fields, dipolar distances, and magnetization fluctuations in single molecule magnets.
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).
authors.affiliation: Department of Physical Chemistry, Ruder Bosković Institute, Bijenicka 54, P.O. Box 180, Zagreb 10002, Croatia. rakvin@irb.hr
authors.forename: B
authors.initials: B
authors.lastname: Rakvin
authors.forename: D
authors.initials: D
authors.lastname: Zilić
authors.forename: N S
authors.initials: NS
authors.lastname: Dalal
authors.forename: J M
authors.initials: JM
authors.lastname: North
authors.forename: P
authors.initials: P
authors.lastname: Cevc
authors.forename: D
authors.initials: D
authors.lastname: Arcon
authors.forename: K
authors.initials: K
authors.lastname: Zadro
mesh_terms: D000327:Adsorption; D001713:Biphenyl Compounds / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D006834:Hydrazines / Q000737:chemistry; D058085:Iron Compounds / Q000493:pharmacokinetics; D008280:Magnetics; D008345:Manganese / Q000737:chemistry; D010851:Picrates; D013499:Surface Properties; D013696:Temperature
chemical_list: D001713:Biphenyl Compounds; D006834:Hydrazines; D058085:Iron Compounds; D010851:Picrates; D008345:Manganese; C004931:1,1-diphenyl-2-picrylhydrazyl