NASSAU 2006 (eBook)

Title Page 3
Copyright Page 4
Table of contents 5
4th Nassau Mossbauer symposium analysis and summary 7
Scientific legacy of Stanley Ruby 10
1 Introduction 10
2 Creation and annihilation of acoustic phonons 11
3 Chopped gamma rays 13
4 Diffusion of ions in cooled liquids 13
5 Unique Mossbauer resonance studies 15
6 Mossbauer spectroscopy using synchrotron radiation 15
7 Conclusions 17
References 17
Mössbauer spectroscopy methodology at the cutting-edge of high-pressure research 19
1 Introduction 19
1.1 The first generation 20
1.2P=F/A 21
2 The second generation 22
2.1 Principles of the diamond anvil cell 22
2.2 A brief history 24
3 Examples of recent 57FeHP-MS 24
3.1 Breakdown of strong correlation the case of Hematite (Fe2O3) [29]24
3.2 The high-spin to low spin transition the case of Wiistite (FeO) [43]28
3.3 Pressure-induced "oxidation" of Fe2+ the case of iron hydroxide (Fe(OH)2) [50]30
3.4 The coordination crossover in magnetite (Fe304) a pressure-induced inverse-to-normal spinel transition [57]32
References 34
Vibrational dynamics of Fe in amorphous Fe-Sc and Fe-AI alloy thin films 37
1 Introduction 38
2 Experimental procedure and sample preparation 38
3 Sample characterization 39
4 NRIXS results and discussion 41
4.1 g(E) and related quantities 41
4.2 The boson peak 46
4.3 Scaling 47
5 Summary 48
References 49
Nuclear Resonance Vibrational Spectroscopy (NRVS) of Fe-S model compounds, Fe-S proteins, and nitrogenase 51
1 Introduction 51
2 Results 52
2.1 Model compounds 52
2.2 Protein studies 54
2.3 Summary 57
3 Experimental 57
References 58
On Spin Hamiltonian fits to Mossbauer spectra of high-spin Fe(II) porphyrinate systems 59
References 64
Mössbauer effect of 151Eu in europium salen complex nanoparticles 65
1 Introduction 65
2 Experimental 66
3 Results and discussion 68
References 70
Velocity scales for Mars Mössbauer data 71
1 Introduction 71
2 Velocity calibration 73
3 Assessment of velocity scales 76
4 Conclusion 77
References 78
Nanowires of iron oxides embedded in Si02 templates 79
1 Introduction 79
2 Experimental 80
3 Results and discussion 81
4 Conclusions 85
References 85
Nuclear forward scattering vs. conventional Mössbauer studies of atomically tailored Eu-based materials 87
1 Introduction 87
2 Atomically tailored photonics materials 88
3 Mössbauer spectroscopy of 151Eu in MgS 89
4 Nuclear forward scattering of MgS:Eu 90
5 Conclusions 92
References 93
A complete solution to the Mössbauer problem, all in one place 94
1 Introduction 94
2 The Mössbauer problem 95
2.1 Magnetic dipole interactions 95
2.2 Electric quadrupole interactions 96
3 Combined interactions 97
3.1 Line position calculation 99
3.2 Line intensity calculation 99
3.3 The Xml 100
3.4 The a(L, m) 102
3.5 M1 transitions 103
3.6 E2 transitions 104
3.7 Mixed M1-E2 transitions 106
4 Adapting the solution to other isotopes 106
References 107
Anisotropic contributions to the transferred hyperfine field studied using a field-induced spin-reorientation 108
1 Introduction 108
2 Experimental methods 109
3 Results 111
3.1 Temperature-induced spin reorientation in TbMn6Sn6-xGax 111
3.2 Field-induced spin-flop in TbMn6Sns5.46In0.54 114
3.2.1 Magnetometry 114
3.2.2 Mössbauer spectroscopy 114
4 Conclusions 118
References 119
Use of Mössbauer spectroscopy to determine the effect of salinity on the speciation of triorganotins in Anacostia River sediments 120
1 Introduction 120
2 Experimental 122
3 Results and discussion 124
References 128
57Fe Mössbauer spectroscopic study of (25 - x)MnO-xZnO-15Fe2O3-60B2O3 glasses 129
1 Introduction 129
2 Experimental 131
3 Results and discussion 131
4 Conclusion 132
References 132
Studying surfaces and thin films using Mössbauer spectroscopy 133
1 Introduction 133
2 Conversion electron Mössbauer spectroscopy 134
2.1 CEMS detector design 135
2.2 Conversion electron ranges in Fe 136
3 X-ray backscattering 138
3.1 XBS detector design 138
3.2 X-ray range in iron 139
4 Application to TRIP steel 141
4.1 Results 142
5 Conclusions 144
References 144
Variations of BaSnF4 fast ion conductor with the method of preparation and temperature 146
1 Introduction 147
2 Experimental methods 148
2.1 Materials 148
2.2 Precipitation reactions 148
2.3 Direct reactions at high temperatures 149
2.4 Characterization 149
3 Results and discussion 150
4 Conclusion 158
References 159
The Mössbauer community in the USA 160
1 History of Mössbauer spectroscopy in the United States 160
2 Analysis of US Mössbauer research 163
3 Possibilities for strengthening the US Mössbauer community 165
4 Conclusion 168
References 168
Two earth years of Mössbauer studies of the surface of Mars with MIMOS II 169
1 Introduction 170
2 The MIMOS II spectrometer 171
3 Meridiani Planum landing site 171
4 Gusev crater landing site 172
5 Summary 176
References 177
Author Index to Volume 170 (2006) 178

"Velocity scales for Mars Mossbauer data (p. 67-68)

David G. Agresti • M. Darby Dyar •
Martha W. Schaefer

Published online: 11 January
2007 © Springer Science + Business Media B.V. 2007

Abstract Raw Mossbauer data acquired from surface rocks and soils by two Mars Exploration Rovers (MERs) are being made available on-line to the general science community for independent analysis and interpretation. The data are released as counts per channel, so a velocity scale must be defined. The Windows-based computer program MERView does this in two steps. In the first, a scale proportional to the true velocity is derived by adjusting the magnitudes of the drive error signal and a phase shift. This report focuses on the second step, in which mm1s units are assigned to the proportional scale by comparing laboratory-measured a-iron peak positions with those of spectra of the internal MER calibration targets. We contrast MERView-derived velocity scales for different MER measurement conditions with the velocity scales provided on-line by the MER team, and conclude that independent velocity calibration is generally desirable.

Key words Mossbauer data Mars· velocitycalibration methodology MER View

1 Introduction

Two Mossbauer spectrometers (MIMOS II) [1] have been operating on the surface of Mars since January 2004 as part of the instrument suite of the Mars Exploration Rovers (MERs) Spirit and Opportunity (http://www.athena.comell.edu/). They have been acquiring spectra of surface rocks and soils in order to contribute to a better understanding of Mars geochemical history, in particular the nature of aqueous processes that may have played a role in defining the observed surface mineralogy.

Analyses of spectral data by the MER Mossbauer team, with inferred mineralogy and interpretations in the geologic context, are presented in several reports [e.g. 2--4]. Given the importance of a full assessment of the data by outside investigators , the general science community is provided with the opportunity for independent analysis by regular releases of the MER data, at roughly 90-day intervals, to two principal web sites, the MER Analysts Notebook at http://anserverl.eprsl.wustl.edu/ and the Planetary Data System (PDS) Geosciences Node at http://pds-geosciences.wustl.edu/.

Mossbauer spectra for each rover are recorded in five detectors in up to thirteen 10-K wide temperature windows «180 K to >290 K), resulting in up to 65 distinct Mossbauer spectra for each sol (Mars day) on which data are recorded. Four detectors record the sample spectra, namely backscatter spectra of surface material, rock, soil, or dust, while detecting 6.4-keV Fe Ko; X-rays and 14.4-keV 57Fe y photons. The fifth detector records in transmission mode the reference spectrum of an internal calibration target consisting of an enriched cc-Fe foil overlaid with enriched a-Fe203 and Fe304.

The raw Mossbauer data for a particular sol, essentially as received from Mars, are embedded in a single 160-kB binarycoded file, the Experimental Data Record (EDR), which also includes other pertinent information such as detector energy spectra, temperature data, and a drive error signal. The structure of the EDR file and the nature of the binary coding are described in a Software Interface Specification document, available on line. Most important for this report is that the Mossbaucr data are provided as counts versus channel, requiring calibration of the velocity scale to mm/s versus channel, which may be accomplished with use of the drive error signal and the properties of the calibration target."