A. L. Barra

Static and dynamic magnetic properties of an [Fe13] cluster (2006)

Van Slageren, J., Rosa, P., Caneschi, A., Sessoli, R., Casellas, H., Rakitin, Y. V., ...

The static and dynamic magnetic properties of an [Fe-13] cluster were investigated using several experimental techniques. The cluster crystallizes in a cubic space group, but careful investigation of...

Sign of excited spin state magnetic anisotropy parameters (2006)

Huang, P., Anderlund, M., Weihe, H., Barra, A. L., Sun, L. C.

By using high frequency high field EPR spectroscopy we demonstrate how to extract the sign of magnetic anisotropy parameters pertinent to excited spin multiplets of antiferromagnetically coupled...

Tuning anisotropy barriers in a family of tetrairon(III) single-molecule magnets with an S=5 ground state (2006)

Accorsi, S., Barra, A. L., Caneschi, A., Chastanet, G., Cornia, A., Fabretti, A. C., ...

Tetrairon(III) Single-Molecule Magnets (SMMs) with a propeller-like structure exhibit tuneable magnetic anisotropy barriers in both height and shape. The clusters [Fe-4(L-1)(2)(dpm)(6)] (1),...

The electronic ground state of [V(urea)6]3+ probed by NIR luminescence, electronic Raman, and high-field EPR spectroscopies (2006)

Beaulac, R., Barra, A. L., Weihe, H., Luneau, D., Reber, C.

The electronic structure of a trigonally distorted vanadium(III) complex, [V(urea)(6)](ClO4)(3), and its deuterated analogue, [V(urea-d(4))(6)](ClO4)(3) has been investigated with Raman,...

Magnetic anisotropy of two trinuclear and tetranuclear CrIIINiII cyanide-bridged complexes with spin ground states S=4 and 5 (2006)

Rebilly, J. N., Catala, L., Charron, G., Rogez, G., Riviere, E., Guillot, R., ...

The trinuclear and the tetranuclear complexes [{iPrtacnCr(CN)(3)}(2){Ni(cyclam)}](NO3)(2) center dot 5H(2)O 1 ( cyclam = 1,4,8,11-tetraazacyclotetradecane, iPrtacn = 1,4,7-...

Spectroscopic, magnetochemical, and crystallographic study of cesium iron phosphate hexahydrate: Characterization of the electronic structure of the iron(II) hexa-aqua cation in a quasicubic environment (2006)

Carver, G., Dobe, C., Jensen, T. B., Janssen, S., Bill, E., ...

Spectroscopic, magnetochemical, and crystallographic data are presented for CsFe(H2O)(6)PO4, a member of a little-known isomorphous series of salts that facilitates the study of hexa-aqua ions in a...

EPR of molecular nanomagnets (2006)

Gatteschi, D., Barra, A. L., Caneschi, A., Cornia, A., Sessoli, R., Sorace, L.

Electron paramagnetic resonance has played a crucial role in the determination of the properties and in explaining the origin of the peculiar behaviour of molecular nanomagnets, i.e., the slow...

Broad-band quasi-optical HF-EPR spectroscopy: Application to the study of the ferrous iron center from a rubredoxin mutant (2006)

Barra, A. L., Hassan, A. K., Janoschka, A., Schmidt, C. L., Schünemann, V.

High-frequency electron paramagnetic resonance (HF-EPR) allows obtaining detailed information on the anisotropy of integer-spin systems, which are usually silent at conventional EPR frequencies (X-...

A comparative reactivity study of microperoxidases based on hemin, mesohemin and deuterohemin (2005)

Ryabova, E. S., Rydberg, P., Kolberg, M., Harbitz, E., Barra, A. L., Ryde, U., ...

Very large ising-type magnetic anisotropy in a mononuclear Ni-II complex (2005)

Rogez, G., Rebilly, J. N., Barra, A. L., Sorace, L., Blondin, G., Kirchner, N., ...

Spin frustration effects in an odd-member antiferromagnetic ring and the magnetic Mobius strip (2005)

Cador, O., Gatteschi, D., Sessoli, R., Barra, A. L., Timco, G. A., Winpenny, R. E. P.

Anisotropic hyperfine interaction in the manganese(III) hexaaqua ion (2005)

Krivokapic, I., Noble, C., Klitgaard, S., Tregenna-Piggott, P., Weihe, H., Barra, A. L.

Resonant photon absorption in Fe8 single-molecule magnets detected via magnetization measurements (2005)

Petukhov, K., Wernsdorfer, W., Barra, A. L., Mosser, V.

High-field/high-frequency EPR studies of spin clusters with integer spin: the multi-frequency approach (2005)

Barra, A. L., Gatteschi, D., Sessoli, R., Sorace, L.

Spectroscopic characterization of the iron-oxo intermediate in cytochrome P450 (2005)

Jung, C., Schunemann, V., Lendzian, F., Trautwein, A. X., Contzen, J., Galander, M., ...

Multi-frequency EPR and Mossbauer spectroscopic studies on freeze-quenched reaction intermediates of nitric oxide synthase (2005)

Jung, C., Lendzian, F., Schunemann, V., Richter, M., Bottger, L. H., Trautwein, A. X., ...

The use of multi-frequency EPR techniques to identify the radicals produced in irradiated beta-blockers (2004)

Engalytcheff, A., Kolberg, M., Barra, A. L., Andersson, K. K., Tilquin, B.

Tyrosine radical formation in the reaction of wild type and mutant cytochrome P450cam with peroxy acids - A multifrequency EPR study of intermediates on the millisecond time scale (2004)

Schünemann, V., Lendzian, F., Jung, C., Contzen, J., Barra, A. L., Sligar, S. G., ...

We report a multifrequency (9.6-, 94-, 190-, and 285-GHz) EPR study of a freeze-quenched intermediate obtained from reaction of substrate-free cytochrome P450cam (CYP101) and its Y96F and Y96F/Y75F...

Energy-barrier enhancement by ligand substitution in tetrairon(III) single-molecule magnets (2004)

Cornia, A., Fabretti, A. C., Garrisi, P., Mortalò, C., Bonacchi, D., Gatteschi, D., ...

Electron paramagnetic resonance spectroscopy of iron(III)-doped MFI zeolite. 1. Multifrequency CW-EPR (2004)

Ferretti, A. M., Barra, A. L., Forni, L., Oliva, C., Schweiger, A., Ponti, A.

Mössbauer- and EPR-snapshots of an enzymatic reaction: The cytochrome P450 reaction cycle (2004)

Schünemann, V., Jung, C., Lendzian, F., Barra, A. L., Teschner, T., Trautwein, A. X.

The magnetic Mobius strip: Synthesis, structure, and magnetic studies of odd-numbered antiferromagnetically coupled wheels (2004)

Cador, O., Gatteschi, D., Sessoli, R., Larsen, F. K., Overgaard, J., Barra, A. L., ...

Structure and bonding of the vanadium(III) hexa-aqua cation. 1. Experimental characterization and ligand-field analysis (2004)

Spichiger, D., Carver, G., Frey, B., Meier, R., Weihe, H., ...

Electronic and molecular structure of high-spin d4 complexes: Experimental and theoretical study of the [Cr(D2O)6]2+ cation in Tutton's salts (2004)

Dobe, C., Noble, C., Carver, G., McIntyre, G. J., Barra, A. L., ...

The use of very high frequency EPR in studies of radicals and metal sites in proteins and small inorganic models (2004)

Barra, A. L., Gräslund, A., Andersson, K. K.

Examples of high-frequency EPR studies in bioinorganic chemistry (2003)

Andersson, K. K., Schmidt, P. P., Katterle, B., Strand, K. R., Palmer, A. E., Lee, S. K., ...

Spectroscopic and structural characterization of the [Fe(imidazole)6]2+ cation (2003)

Carver, G., Barra, A. L., Neels, A., Stride, J. A.

Rational design of large-spin clusters based on the hexacopper(II) siloxanolate core (2003)

Abbati, G. L., Barra, A. L., Caneschi, A., Cornia, A., Costantino, A. F., Gatteschi, D., ...

Ferromagnetic and antiferromagnetic intermolecular interactions in a new family of Mn4 complexes with an energy barrier to magnetization reversal (2003)

Boskovic, C., Bircher, R., Güdel, H. U., Paulsen, C., Wernsdorfer, W., ...

High-field, multifrequency EPR study of the [Mn(OH2)6]3+ cation: Influence of π-bonding on the ground state zero-field-splitting parameters (2003)

Weihe, H., Barra, A. L.

The use of very high frequency EPR in studies of radicals and metal sites in proteins and small inorganic models (2003)

Barra, A. L., Gräslund, A., Andersson, K. K.

Photon-assisted tunnelling in a Fe8 single-molecule magnet (2003)

Sorace, L., Werndorfer, W., Thirion, C., Barra, A. L., Pacchioni, M., Mailly, D., ...

Origin of second-order transverse magnetic anisotropy in Mn12-acetate (2002)

Cornia, A., Sessoli, R., Sorace, L., Gatteschi, D., Barra, A. L., Daiguebonne, C.

The symmetry breaking effects for quantum tunneling of the magnetization in Mn-12-acetate, a molecular nanomagnet, represent an open problem. We present structural evidence that the disorder of the...

Multifrequency EPR study and density functional g-tensor calculations of persistent organorhenium radical complexes (2002)

Frantz, S., Hartmann, H., Doslik, N., Wanner, M., Kaim, W., ...

The dinuclear radical anion complexes {(mu- L)[Re(CO)(3)Cl](2)}(.-), L = 2,2'-azobispyridine (abpy) and 2,2'-azobis(5-chloropyrimidine) (abcp), were investigated by EPR at 9.5, 94, 230, and 285 GHz...

Is the axial zero-field splitting parameter of tetragonally elongated high-spin manganese(III) complexes always negative? (2002)

Mossin, S., Weihe, H., Barra, A. L.

Disorder effects in Mn12-acetate at 83 K (2002)

Cornia, A., Fabretti, A. C., Sessoli, R., Sorace, L., Gatteschi, D., Barra, A. L., ...

The structure of hexadeca-mu-acetato-tetraaquadodeca-mu(3) oxo- dodecamanganese bis(acetic acid) tetrahydrate, [Mn12O12 (CH3COO)(16) (H2O)(4)].2CH(3)COOH.4H(2)O, known as Mn-12- acetate, has been...

EPR studies on a stable sulfinyl radical observed in the iron-oxygen-reconstituted Y177F/I263C protein R2 double mutant of ribonucleotide reductance from mouse (2002)

Adrait, A., Öhrström, M., Barra, A. L., Thelander, L., Gräslund, A.

Ribonucleotide reductase (RNR) catalyzes the biosynthesis of deoxyribonucleotides. The active enzyme contains a diiron center and a tyrosyl free radical required for enzyme activity. The radical is...

The use of high field/frequency EPR in studies of radical and metal sites in proteins and small inorganic models (2002)

Andersson, K. K., Barra, A. L.

Low temperature electron paramagnetic resonance (EPR) spectroscopy with frequencies between 95 and 345 GHz and magnetic fields up to 12 T have been used to study radicals and metal sites in proteins...

Electron spin resonance of Ni-doped CuGeO3 in the paramagnetic, spin-Peierls, and antiferromagnetic states: Comparison with nonmagnetic impurities (2002)

Grenier, B., Monod, P., Hagiwara, M., Matsuda, A., Katsumata, K., Clement, S., ...

We have performed electron-spin-resonance measurements on single crystals of the doped spin-Peierls compounds CuGe1- ySiyO3 and Cu1-xMxGeO3 with M=Zn, Mg, Ni (x,yless than or equal to0.1). The first...

Magnetic anisotropy of the antiferromagnetic ring [Cr8F8PiV16] (2002)

Van Slageren, J., Sessoli, R., Gatteschi, D., Smith, A. A., Helliwell, M., Winpenny, R. E. P., ...

A new tetragonal (P42(1)2) crystalline form of [Cr(8)F(8)Piv(16)] (HPiv = pivalic acid, trimethyl acetic acid) is reported. The ring-shaped molecules, which are aligned in a parallel fashion in the...

Magnetic anisotropy of the antiferromagnetic ring [Cr8F8Piv16] (2002)

Van Slageren, J., Sessoli, R., Gatteschi, D., Smith, A. A., Helliwell, M., Winpenny, R. E. P., ...

A new tetragonal (P42(1)2) crystalline form of [Cr(8)F(8)Piv(16)] (HPiv = pivalic acid, trimethyl acetic acid) is reported. The ring-shaped molecules, which are aligned in a parallel fashion in the...

The origin of second-order transverse magnetic anisotropy in Mn12-acetate (2001)

Cornia, A., Sessoli, R., Sorace, L., Gatteschi, D., Barra, A. L., Daiguebonne, C.

The problem of the role of transverse fields in Mn12-acetate, a molecular nanomagnet, is still open. We present structural evidences that the disorder of the acetic acid of crystallization indices...

Electron Spin Resonance of Ni-doped CuGeO$_3$ in the paramagnetic, spin-Peierls and antiferromagnetic states: Comparison with non-magnetic impurities (2001)

Grenier, B., Monod, P., Hagiwara, M., Matsuda, M., Katsumata, K., Clément, S., ...

We have performed Electron Spin Resonance measurements on single crystals of the doped spin-Peierls compounds CuGe$_{1-y}$Si$_y$O$_3$ and Cu$_{1-x}$M$_x$GeO$_3$ with M = Zn, Mg, Ni ($x, y\leq 0.1$)....

Tuning of the magnetic properties of the high spin molecular cluster Fe8 (2001)

Barra, A. L., Bencini, F., Caneschi, A., Gatteschi, D., Paulsen, C., Sangregorio, C., ...

The synthesis, crystal structure and magnetic characterization of a high spin cluster comprising eight iron ions, are presented in this contribution. The cluster has formula...

High-frequency EPR: an occasion for revisiting ligand field theory (2001)

Gatteschi, D., Sorace, L., Sessoli, R., Barra, A. L.

The use of high-field electron paramagnetic resonance (EPR) made possible for the first time to obtain detailed information on the anisotropy of integer-spin systems, which are usually silent at...

High-frequency EPR spectroscopy of single-molecule magnets: a case study (2001)

Barra, A. L.

A high-frequency electron paramagnetic resonance (EPR) study of a single-molecule magnet, [Mn12O12(CH3COO)(16)(H2O)(4)] (.) 2CH(3)COOH (.) 4H(2)O, has been performed. The analysis of the spectra...

The use of high field/frequency EPR (HF-EPR) in studies of radical and metal sites in proteins and small inorganic models (2001)

Andersson, K. K., Barra, A. L.

Restoring proper radical generation by azide binding to the iron site of the E 238 A mutant R 2 protein of ribonucleotide reductase from Escherichia coli (2001)

Assarsson, M., Andersson, M. E., Hogbom, M., Persson, B. O., Sahlin, M., Barra, A. L., ...

Tuning the magnetic properties of the high-spin molecular cluster Fe8 (2001)

Barra, A. L., Bencini, F., Caneschi, A., Gatteschi, D., Paulsen, C., Sangregorio, C., ...

Analysis of the structural and electronic properties of new azide and fluoride mononuclear Mn(III) complexes by high frequency EPR (2001)

Duboc-Toia, C., Mantel, C., Barra, A. L., Hassan, A., Deronzier, A., ...

High-frequency EPR study of a new mononuclear manganese(III) complex: [(terpy)Mn(N3)3] (terpy = 2,2':6',2"-terpyridine) (2001)

Limburg, J., Vrettos, J. S., Crabtree, R. H., Brudvig, G. W., De Paula, J. C., Hassan, A., ...

NMR and parity nonconservation. Experimental requirements to observe a difference between enantiomer signals (2001)

Robert, J. B., Barra, A. L.

Spectroscopic and electron paramagnetic resonance behavior of trinuclear metallic clusters encapsulated in [Mn+3(H2O)x(BiW9O33)2](18-3n)- heteropolyanion (Mn+ = (VO)II, x=0 and Mn+ = CrIII, MnII, FeIII, CoII, NiII, CuII, x=3) (2001)

Rusu, D., Craciun, C., Barra, A. L., David, L., Rusu, M., Rosu, C., ...

High-frequency EPR spectra of [Fe8O2(OH)12(tacn)6]Br8: A critical appraisal of the barrier for the reorientation of the magnetization in single-molecule magnets (2000)

Barra, A. L., Gatteschi, D., Sessoli, R.

Nature of the magnetic ground state in the A1C60 series (2000)

Coulon, C., Duval, J., Lavergne, C., Barra, A. L., Penicaud, A.

Integer-spin multifrequency EPR spectroscopy of a ferromagnetically coupled, oxo-bridged (MnMnIV)-MnIV model complex (2000)

Duboc-Toia, C., Hummel, H., Bill, E., Barra, A. L., Chouteau, G., Wieghardt, K.

Heterogeneity of the local electrostatic environment of the tyrosyl radical in Mycobacterium tuberculosis ribonucleotide reductase observed by high-field electron paramagnetic resonance (2000)

Liu, A. M., Barra, A. L., Rubin, H., Lu, G. Z., Gräslund, A.

Towards nanostructured arrays of single molecule magnets: New Fe19 oxyhydroxide clusters displaying high ground state spins and hysteresis (2000)

Goodwin, J. C., Sessoli, R., Gatteschi, D., Barra, A. L., Wernsdorfer, W., Powell, A. K., ...

High-frequency (245 GHz) and X-band EPR study of stable dicopper radical complexes. (1999)

Barra, A. L., Brunel, L. C., Baumann, F., Schwach, M., Moscherosch, M., Kaim, W.

Single-molecule magnet behavior of a Tetranuclear iron(III) complex. The origin of slow magnetic relaxation in iron (III) cluster. (1999)

Barra, A. L., Caneschi, A., Cornia, A., Gatteschi, D., Sangregorio, C., ...

Slow magnetic relaxation of [Et3NH]2[Mn(CH3CN)4(H2O)2] [Mn10O4(biphen)4Br12](biphen=2,2′-biphenoxide) at very low temperature. (1999)

Barra, A. L., Caneschi, A., Gatteschi, D., Goldberg, D. P., Sessoli, R.

High magnetic field properties and ESR of the Li1-zNi1+zO2 compounds. (1999)

Barra, A. L., Chouteau, G., Stepanov, A., Rougier, A., Delmas, C.

Electron spin resonance of CuGeO3: opposite effect of Ni- and Zn- or Si-doping. (1999)

Grenier, B., Barra, A. L., Monod, P.

High-field, multifrequency EPR study of the vanadium(III) hexaaqua cation. (1999)

Weihe, H., Bendix, J., Barra, A. L., Güdel, H. U.

Magnetic properties of a new spin cluster topology with high spin ground state: the spin cluster [MnII4MnIII3(teaH)3(tea)3](ClO4)2.3MeOH. (1998)

Pilawa, B., Kelemen, M. T., Wanka, S., Geisselmann, A., Barra, A. L.

High-frequency EPR and pulsed Q-band ENDOR studies on the origin of the hydrogen bond in tyrosyl radicals of ribonucleotide reductase R2 proteins from mouse and herpes simplex virus type 1. (1998)

Van Dam, P. J., Willems, J. P., Schmidt, P. P., Pötsch, S., Barra, A. L., Hagen, W. R., ...

High frequency EPR spectroscopy of large metal ion clusters: from zero-field splitting to quantum tunneling of the magnetization. (1998)

Barra, A. L., Brunel, L. C., Gatteschi, D., Pardi, L., Sessoli, R.

High magnetic field spin resonance in nearly stoichiometric LiNiO2: evidences for magnetic cluster formation. (1998)

Barra, A. L., Chouteau, G., Stepanov, A., Delmas, C.

High frequency EPR spectra of a molecular nanomagnet provide a key to understand Quantum Tunneling of the Magnetization (1997)

Barra, A. L., Gatteschi, D., Sessoli, R.

EPR spectra have been recorded in very high field, up to 25T, and at high frequency, up to 525 GHz, on a polycristalline sample of Mn12ac (see paper for detailed formula), the first example of...

Very high field EPR study of a molecular nanomagnet. (1997)

Barra, A. L., Caneschi, A., Gatteschi, D., Sessoli, R.