81. G. Wortmann, F. Godler, B. Perscheid, G. Kaindl, R. Schlögl 
 Chemical and Microstructural Organization of Graphite Intercalated with 
 SbCl₅ and SbF₅ from ¹²¹Sb-Mössbauer Spectroscopy 
 Synthetic Metals 26, 109-137 (1988). 

82. G. Wortmann, S. Blumenröder, A. Freimuth, D. Riegel 
 ¹⁵¹Eu-Mössbauer Study of the High-Tc Superconductor EuBa₂Cu₃O_7-x
 Phys. Lett. A126, 434-38 (1988). 

83. G. Wortmann, A. Kolodziejczyk, C.T. Simmons, G. Kaindl 
 Magnetic Ordering of the Gd Sublattice in Superconducting GdBa₂Cu₃O_7-x
 Physica C 153-155, 1547-48 (1988). 

85. B. Perscheid, I. Nowik, G. Wortmann, G. Schmiester, G. Kaindl, I. Felner 
 Mössbauer and L_III-Edge Absorption Line Intensities of Eu²⁺ and Eu³⁺ in 
 Inhomogeneous Mixed-Valent EuCo₂Si_2-xGe_x 
 Z. Physik B 73, 1376-82 (1988). 

86. W. Krone, G. Wortmann, G. Kaindl 
 Intercalate Structure of Halogen-Intercalated Graphite 
 Synthetic Metals 29, F 247-252 (1989). 

87. G. Wortmann 
 Edge Spectroscopy 
 Hyperfine Interactions 47, 179-202 (1989). 

88. M. Tiedtke and G. Wortmann 
 ¹²⁹I-Mössbauer Study of the Charge Transfer in ICl- and IBr-Graphite 
 Intercalation Compounds 
 Synthetic Metals 34, 404-410 (1989). 

89. W. Krone, G. Wortmann, G. Kaindl, H. Zabel 
 Local Structure in the Ternary Alkalimetal-Graphite Compounds K_1-xRb_xC₈
 Studied by X-Ray Absorption 
 Synthetic Metals 34, 261-266 (1989). 
 

90. G. Wortmann, W. Krone, G. Kaindl 
 Structure Determination in Intercalated Graphite by Polarized XAFS Analysis 
 Physica B 158, 535-36 (1989). 

91. G. Wortmann and J. Zukrowski 
 Magnetic Properties of Gd₆Mn₂₃H_x from  ¹⁵⁵Gd- and  ⁵⁷Fe-Mössbauer 
 Spectroscopy 
 Z. Phys. Chem. (NF) 163, 661-668 (1989) 

92. J. Zukrowski, G. Wortmann, G.A. Stewart 
 Mössbauer Effect Study of the Magnetic Order in Th₆Mn₂₃H_x
 Z. Phys. Chem. (NF) 163, 669-670 (1989) 

93. G. Wortmann, A. Kolodziejczyk, M. Bergold, G. Stadermann, C.T. Simmons, 
 G. Kaindl 
 Mössbauer Studies of YBa₂Cu₃O_7-x-Type High-T_c Superconductors 
 Hyperfine Interactions 50, 555-568 (1989). 

94. G. Schmiester, G. Wortmann, H. Winzen, K. Syassen, E. Kaldis 
 Effect of Pressure on the Yb Valency in YbS and YbTe
 High-Pressure Research 3, 186-88 (1990). 

95. G. Schmiester, G. Wortmann, G. Kaindl, H. Bach, F. Holtzberg 
 Pressure-Induced Valence Changes in EuS and EuTe 
 High-Pressure Research 3, 192-94 (1990). 

96. I. Nowik, K. Muraleedharan, G. Wortmann, B. Perscheid, G. Kaindl, N.C. Noon 
 Spin-Reorientation Transition in Nd₂Fe₁₄B by ¹⁴⁵Nd-Mössbauer Spectroscopy 
 Solid State Commun. 76, 967-970 (1990). 

97. M. Tiedtke and G. Wortmann 
 The Chemical Nature of Interhalogen Molecules in ICl- and IBr-Graphite 
 Hyperfine Interactions 53, 419-424 (1990). 

98. E.A. Bychkov, Yu.V. Ganzha, Yu.S. Grushko, M.F. Molkanov, Yu.G. Vlasov, 
 G. Wortmann 
 ¹²⁹I-Mössbauer Spectroscopic Study of Iodine Containing Chalcogenide 
 Glasses 
 Hyperfine Interactions 55, 921-926 (1990). 

99. M. Bergold, G. Wortmann, G.A. Stewart 
 Crystalline-Electric Field Interactions in DyBa₂Cu₃O_7-x and TmBa₂Cu₃O_7-x
 from ¹⁶¹Dy- and ¹⁶⁹Tm-Mössbauer Spectroscopy 
 Hyperfine Interactions 55, 1205-1212 (1990). 

100. G. Wortmann, M. Tiedtke, E.A. Bychkov, Yu.S. Grushko 
 ¹²⁹I-Mössbauer Study of Diffusion Effects in the Superionic Conductor Ag₃SI 
 Hyperfine Interactions 56, 1595-1502 (1990). 

101. G. Wortmann and I. Felner 
 Magnetic Order of the Pr Sublattice in Tetragonal and Orthorhombic 
 Pr_1-xGd_xBa₂Cu₃O_7-x Observed by ¹⁵⁵Gd-Mössbauer Spectroscopy 
 Solid State Commun. 75, 981-985 (1990). 

102. I. Nowik, I. Felner, E.R. Bauminger, G. Wortmann, G. Kaindl 
 Superconducting Magnetic Phase Diagram of High-T_c Systems 
 Proc. XXV Zakopane School of Physics, Vol.1: Condensed Matter Studied by 
 Nuclear Methods, World Scientific Publ. (Singapore 1990), p. 53-69. 

103. E.V. Sampathkumaran, G. Wortmann, G. Kaindl 
 Mössbauer Studies of Gd-Doped Bismuth-Based Ceramic Superconductors 
 Bull. Mater. Sci. 14, 703-707 (1991). 

104. G. Wortmann, I. Nowik, B. Perscheid, G. Kaindl, I. Felner 
 Critical Evaluation of Eu Valences by L_III-Edge Absorption and Mössbauer 
 Spectroscopy of EuNi₂Si_2-xGe_x
 Phys. Rev. B 43, 5261-68 (1991) 

105. G. Wortmann, P. Sladeczek, G. Stadermann,I. Felner, G. Kaindl 
 Pr-LI-III Near-Edge Study of 4f-Hybridization in Orthorhombic and Tetragonal 
 PrBa₂Cu₃O_7-x
 in: X-Ray Absorption Fine Structure, S.S. Hasnain, Ed. (Ellis Horwood, 1991), 
 p. 386-389. 

106. M. Abdel-Hamied, G. Wortmann, H. Naarmann 
 Mössbauer Study of Polyiodine Anions in N-(CH)_x and S-(CH)_x
 Synthetic Metals 41-43, 175-80 (1991). 

107. G. Wiesinger, M. Forsthuber, F. Lehner, G. Hilscher, A. Fischer, L. Schlapbach,  G. Wortmann 
 On Unstable Magnetic Ordering in Ce-3d Compounds and Their Hydrides 
 J. Less-Common Metals 172-174, 451-458 (1991). 

108. M. Gruber, M. Abdel-Hamied, G. Wortmann, H.-K. Roth, E. Fanghänel, 
 K. Klostermann 
 Mössbauer and Raman Spectroscopy Studies of Iodine-Doped 
 Poly-Tetrathiafulvalenes (P-TTF) 
 Synthetic Metals 44, 55-64 (1991). 

109. E. Bychkov, Yu. Grushko, G. Wortmann 
 ¹²⁹I-Mössbauer Study of Superionic Glasses AgI-Sb₂S₃: Local Structure and 
 Diffusion Effects 
 Hyperfine Interactions 69, 709-712a (1991). 

110. G. Wortmann, E.A. Bychkov, Yu.S. Grushko 
 129I-Mössbauer Study of Molecular Dynamics in the Organic Superconductor 
  ß-(BEDT-TTF)₂I₃
 Hyperfine Interactions 70, 1179-1184 (1992). 

111. Z. Chen, P. Hettkamp, H. Hesse, M. Müther, G. Nowitzke, G. Stadermann, 
 G. Wortmann 
 ⁵⁷Fe-Mössbauer Study of the High-Tc System GdBa₂Cu₃O_7-x: 
 Local Binding Strength and Oxygen Coordination of the Fe Sites 
 Hyperfine Interactions 70, 1185-1188a (1992). 

112. J. Freund, G. Wortmann, W. Paulus, W. Krone 
 Polarization Dependent X-Ray Absorption Study of Cu_xNbS₂ and Cu_xNbSe₂
 J. Alloys and Compounds 187, 157-169 (1992). 

113. Yu.S. Grushko, G. Wortmann, M.F. Kovalev, L.I. Molkanov, Yu.V. Ganzha, 
 Yu.A. Ossipyan, O.V. Zharikov 
 ¹²⁹I-Mössbauer Study of Iodine-Doped C₆₀
 Solid State Commun. 84, 505-509 (1992). 

114. G. Wortmann, J. Freund, G. Nowitzke, H. Werner, R. Schlögl 
 X-Ray Absorption Study of Iodine-Doped C₆₀
 Springers Series of Solid State Sciences, Vol. 113, 492-496 (1993). 

115. M. Müther, G. Wortmann, I. Felner, I. Nowik 
 155Gd-Mössbauer Studies of the T'-,T*- and T-Phases of La_2-x-yGd_xSr_yCuO₄
 Physica C 209, 428-436 (1993). 

116. Z. Hu, G. Kaindl, D. Vandre, R. Hoppe, G. Wortmann 
 X-Ray Absorption Study of Tetravalent Dy Compounds: Cs₂RbDyF₇ and 
 Cs₂KDyF₇
 J. Alloys and Compounds 205, 263-269 (1994). 

117. E.A. Bychkov and G. Wortmann 
 ¹²¹Sb-Mössbauer Studies of Dielectric and Ion-Conducting Antimony 
 Chalcogenide-Based Glasses 
 J. of Non-Crystalline Solids 159, 162-172 (1993). 

118. G. Nowitzke, J. Dumschat, G. Wortmann, H. Werner and R. Schlögl 
 X-Ray Absorption Study of the Local Structure at Potassium and Rubidium 
 in Superconducting K_3-xRb_xC₆₀
 Mol. Cryst. Liq. Cryst. 245, 321-326 (1994). 

119. G. Wortmann, Yu.S. Grushko, A. Bolotov, E.A. Bychkov, W. Bensch, 
 H. Werner, R. Schlögl 
 ¹²⁹I-Mössbauer- and X-Ray Diffraction Study of the Iodine-Fullerene Compound 
 C₆₀(I₂)~2 
 Mol. Cryst. Liq. Cryst. 245, 313-320 (1994). 

120. G. Hilscher, T. Holubar, G. Schaudy, J. Dumschat, M. Strecker, G. Wortmann, 
 X.Z. Wang, B. Hellebrand, D. Bäuerle 
 Rare Earth Magnetism and Superconductivity in RBaSrCuO₃O_7-x  (R = Gd, Pr) 
 Physica C 224, 330-344 (1994). 

121. H.J. Hesse and G. Wortmann 
 151Eu-Mössbauer Study of Pressure-Induced Valence Transitions in 
 EuM₂Ge₂ (M = Ni. Pd, Pt) 
 Hyperfine Interactions 93, 1499-1504 (1994). 

122. J. Dumschat, G. Wortmann, I. Felner 
 L_II,III Near-Edge Study of Tetravalent Pr-Oxides: PrBaO₃ and PrO₂
 Physica B 208 & 209, 313-315 (1995). 

123. G. Nowitzke, G. Wortmann, H. Werner. R. Schlögl 
 EXAFS Studies of Superconducting A₂BC₆₀ Compounds 
 Physica B 208 & 209, 273-274 (1995). 

124. X.Z. Wang, B. Hellebrand, D. Bäuerle, M. Strecker, G. Wortmann, W. Lang 
 Oxygen Ordering and Superconductivity in GdBaSrCu₃O_7-x
 Physica C 242, 55-62 (1995). 

125. W. Bensch, O. Helmer, J. Lu, H.-J. Hesse, G. Wortmann, M. Kraus, K. Lüders 
 Crystal Structures, Chemical Reactivity, Magnetic Properties and Mössbauer 
 Spectroscopy of the Quasi-Ternary Compounds TlV_5-yFeyS₈ (y = 0.5 and 1) 
 J. Solid State Chem. 119, 147-156 (1995). 

126. R. Rüffer, A.I. Chumakov, H. Grünsteudel, H.F. Grünsteudel, G. Grübel 
 O.Leupold, J. Metge, H.-J. Hesse, G. Wortmann, H.A. Goodwin 
 neV Energy Resolution and sub-ns Timing Resonant Scattering 
 ESRF Newsletter, Vol. 22, Nov. 1994, p. 12-14 (Report). 

127. A.I. Chumakov, A.Q.R. Baron, J. Arthur, S.L. Ruby, G.S. Brown, 
 G.V. Smirnov, U. van Bürck, G. Wortmann 
 Nuclear Scattering of Synchrotron Radiation by ¹⁸¹Ta 
 Phys. Rev. Lett. 75, 549-52 (1995). 

128. J. Lu, H.J. Hesse, J. Zukrowski, J. Przewoznik, G. Wortmann 
 Effect of Pressure and Temperature on the Magnetic Properties of TiFe₂
 Conference Proceedings Vol. 50, "ICAME 95" (SIF, Bologna, 1996), p. 246. 

129. H. Welker, H.F. Grünsteudel, G. Ritter, R. Lübbers, H.-J. Hesse, G. Nowitzke, 
 G. Wortmann, H.A. Goodwin 
 Combined Mössbauer and EXAFS Study of the High-Spin/Low-Spin Transition 
 in [Fe(II)(bpp)₂](BF₄)₂
 see Ref. 128, p. 19-22. 

130. M. Strecker and G. Wortmann 
 High-Pressure Study of GdMn₂ with the 86.5 keV Resonance of Gd-155 
 see Ref. 128, p. 235-238. 

131. H.F. Grünsteudel, H.-J. Hesse, A.I. Chumakov, H. Grünsteudel, O. Leupold, 
 J. Metge, R. Rüffer, G. Wortmann 
 The a-Fe/e-Fe Transition as an Example of Nuclear Forward Scattering on 
 Fe-57 under High Pressure 
 Hyperfine Interactions C1, 509-512 (1996) and Ref. 128, p. 853-856. 

132. G. Nowitzke, G. Wortmann, H. Werner, R. Schlögl 
 EXAFS Study of Local Structure at the Alkali Ions in Superconducting 
 K₂RbC₆₀, K₂CsC₆₀, Rb₂CsC₆₀, and Rb₃C₆₀
 Phys. Rev. B 54, 13230-41 (1996). 

133. E. Bychkov, A. Bolotov, Yu. Grushko, Yu. Vlasov, G. Wortmann 
 Ionic Diffusion and Local Hopping in Copper Chalcohalide Glasses Measured 
 Using ⁶⁴Cu Tracer and ¹²⁹I-Mössbauer Spectroscopy 
 Solid State Ionics 90, 289-294 (1996). 

134. S.N. Kolesnik, J. Dumschat, G. Nowitzke, D. Herein, Yu.S. Grushko, 
 G. Wortmann 
 Local Structure in C₆₀(I₂)_x and C₇₀(I₂)_x from XRD, EXAFS, and Mössbauer 
 Effect 
 in: "Fullerenes and Fullere Nanostuctures" (World Scientific, Singapore, 1996), 
 p. 438-441. 

135. I. Felner, G. Hilscher, H. Michor, G. Wortmann, J. Dumschat, V.P.S. Awana, 
 S.K. Malik 
 Structural and Unique Magnetic Properties of PrBa₂Fe₃O₈
 Phys. Rev. B 54, 11999-12002 (1996). 

136. H.J. Hesse, R. Lübbers, M. Winzenick, H.W. Neuling, G. Wortmann 
 Effect of Pressure and Temperature on the Eu Valence in EuNi₂Ge₂ and 
 Related Systems Studied by Mössbauer Effect, X-Ray Absorption and X-Ray 
 Diffraction 
 J. Alloys Compounds 246, 220-231 (1997).

137. R. Mallik, E.V. Sampathkumaran, P.L. Paulose, J. Dumschat, G. Wortmann 
 Kondo Lattice Behavior and Multiple Characteristic Temperatures 
 in CeIr₂Ge₂
 Phys. Rev. B 55, 3627-3630 (1997). 

138. Th. Braun, M. Wohlers, T. Belz, G. Nowitzke, G. Wortmann, Y. Uchida, 
 N. Pfänder, R. Schlögl 
 Fullerene Based Ruthenium Catalysts: A Novel Approach for Anchoring Metal 
 to Carbonaceous Supports 
 Catal. Lett. 43, 161-166 (1997). 

139. J. Dumschat, S.N. Kolesnik, G. Nowitzke, D. Herein, Yu.S. Grushko, 
 G. Wortmann 
 EXAFS Study of the Local Iodine Structure in  C₆₀(I₂)_x and in C₇₀(I₂)_x
 J. Physique IV, Vol. 7, C2-649-50 (1997). 

140. R. Lübbers, G. Nowitzke, H.A. Goodwin, G. Wortmann 
 X-Ray Absorption Study of the High-Spin/Low-Spin Transition in 
 [Fe(II)(bpp)₂](BF₄)₂
 J. Physique IV, Vol. 7, C2-651-52 (1997). 

141. G. Nowitzke, M. Wohlers, Th. Baun, R. Schlögl, G. Wortmann 
 Local Structure of Ru in Ru-C₆₀ and  Ru-Fullerene Black Compounds 
 J. Physique IV, Vol. 7, C2-945-46 (1997). 

142. J. Dumschat, R. Lübbers, I. Felner, G. Lucaceau, G. Wortmann 
 (Tb, Ce)-L_III XAS High-Pressure Study of tetravalent BaTbO₃ and SrCeO₃
 J. Physique IV, Vol. 7, C2-1019-20 (1997). 

143. R. Lübbers, J. Dumschat, G. Wortmann, E. Bauer 
 Temperature and Pressure Induced Valence Transitions in YbCu_5-xGa_x Studied 
 by Yb-L_III XANES 
 J. Physique IV, Vol. 7, C2-1021-22 (1997). 

144. G. Nowitzke, H. Meier, R. Lübbers, J. Dumschat, G. Wortmann 
 EXAFS Study of Oxygen Distortions in Gd₂CuO₄ as Function of Temperature 
 and Pressure 
 J. Physique IV, Vol. 7, C2-1023-24 (1997). 

145. R. Mallik, E.V. Sampathkumaran, J. Dumschat, G. Wortmann 
 Magnetic Ordering and Spin Fluctuation Behaviour in Compounds of the Type 
  Ce₂(Pd,Rh)₂In 
 Solid State Commun. 102, 59-64 (1997). 

146. J. Zukrowski, M. Strecker, G. Wortmann, J. Przewoznik, K. Krop 
 X-Ray Diffraction and ¹⁵⁵Gd-Mössbauer Effect Study of GdMn₂H_x (0 < x < 4.3) 
 J. Alloys Compounds 261, 47-53 (1997). 

147. H.F. Grünsteudel, H.-J. Hesse, R. Rüffer, G. Wortmann, A.I. Chumakov, 
 A.Q.R. Baron, H. Grünsteudel, O. Leupold, J. Metge 
 Spatial Distribution of Magnetic and Nonmagnetic Phases in Nuclear Forward 
 Scattering of Synchrotron Radiation 
 Aust. J. Phys. 51, 453 (1998). 

148. M. Strecker, P. Hettkamp, G. Wortmann and G.A. Stewart, 
 ¹⁵⁵Gd-Mössbauer Study of Gd₂BaCuO₅
 J. Magn. Magn. Mat. 177-181, 1095-96 (1998). 

149. R. Mallik, E.V. Sampathkumaran, M. Strecker, G. Wortmann 
 Observation of a Minimum in the Temperature Dependent Electrical 
 Resistance above Magnetic Ordering in a Gd Alloy 
 Europhys. Lett. 41, 315-320 (1998). 

150. R. Mallik, E.V. Sampathkumaran, M. Strecker, G. Wortmann, Y. Ueda 
 Complex magnetism in a new alloy, Eu₂PdSi₃, with two crystallographically 
 inequivalent sites 
 J. Magn. Magn. Mat. 185, L135-L143 (1998). 

151. R. Lübbers, H.J. Hesse, H.F. Grünsteudel, R. Rüffer, J. Zukrowski, 
 G. Wortmann 
 Probing Magnetism in the Megabar Range 
 ESRF Highlights 1996/97, p. 56 (Report). 

152. R. Lübbers, H.-J. Hesse, H.F. Grünsteudel, R. Rüffer, J. Zukrowski, 
 G. Wortmann
 High-Pressure Studies of Magnetism by Nuclear Scattering of Synchrotron 
 Radiation
 Proc. 2^nd Russian-German Workshop on Synchrotron Radiation Research, 
 in: Poverhnost 1998, Vol. 8-9, p. 134-139 (Russian Acad. Science, ISSN 0207-
-3528), engl. transcription: "Surface Investigations: X-ray, Synchrotron and Neutron 
 Techniques" (Gordon & Breach, 1999).

153. M. Pleines, R. Lübbers, M. Strecker, G. Wortmann, O. Leupold, J. Metge,
 Yu.V. Shvyd'ko, E. Gerdau
 Pressure-Induced Valence Transition in EuNi₂Ge₂ Studied by
 Eu-151 Nuclear Forward Scattering of Synchrotron Radiation"
 Hyperfine Interactions 120/121, 181-185 (1999).

154. R. Lübbers, M. Pleines, H.-J. Hesse, G. Wortmann, H.F. Grünsteudel,
 R. Rüffer, O. Leupold, J. Zukrowski
 Magnetism under high pressure studied by ⁵⁷Fe and ¹⁵¹Eu nuclear 
 scattering of synchrotron radiation
 Hyperfine Interactions 120/121, 49-58 (1999).

155. M. Strecker and G. Wortmann 
 High-pressure ¹⁵⁵Gd-Mössbauer study of magnetic properties in
 GdM₂ Laves phases (M = Al, Mn, Fe)
 Hyperfine Interactions 120/121, 187-191 (1999).

156.  H. Giefers, F. Nessel, S.I. Györy, M. Strecker, G. Wortmann, Yu.S. Grushko,
E.G. Alekseev, V.S. Koslov
Gd-L_III EXFAS study of structural and dynamic properties of Gd@C₈₂ between 10 and 300K.
Carbon 37, 721-725 (1999).

157. O. Leupold, E. Gerdau, M. Gerken, H.D. Rüter, R. Lübbers, M. Pleines, 
M. Strecker, G. Wortmann et al. 
Charge Fluctuations and Magnetism Studied by Nuclear Forward Scattering at the ¹⁵⁵Eu Resonance
ESRF Highlights 1997/1998, p. 37-39 (Report).

158.  S. Majumdar, R. Mallik, E.V. Sampathkumaran, K. Rupprecht, G. Wortmann
 Magnetic behaviour of Eu₂CuSi₃: Large negative magnetoresistance above
Curie temperature
Phys. Rev. B 60, 6770-6774 (1999). 

159. R. Lübbers, G. Wortmann, H.F. Grünsteudel
 High-Pressure Studies with Nuclear Scattering of Synchrotron Radiation
 Chapter in: “Nuclear Resonant Scattering of Synchrotron Radiation: Principles and
Applications“ (edited by E. Gerdau and H. de Waard, Baltzer Science Publ. 1999), p. 529 and 
Hyperfine Interactions 123/124, 529-559 (1999).

160. Yu. S. Grushko, E.G. Alekseev, V.S. Koslov, L.I. Molkanov, G. Wortmann,
H. Giefers, K. Rupprecht, M.A. Khodorkovskii
 ¹⁶¹Dy Mössbauer study of the endohedral metallofullerenes Dy@C_n (n = 80, 82, 84)
 Hyperfine Interactions 126, 121-126 (2000).

161. G. Wortmann
Study of Magnetism in the Megabar Range by Nuclear Resonance Scattering of
Synchrotron Radiation
in: Science and Technology of High Pressure (Proc. Int. High-Pressure Conf. AIRAPT-17 (Hawaii, 1999), 
edited by M.H. Manghnani, W.J. Nellis and M.F. Nicol) 
Univeristies Press, Hyderabad, India, 2000). 

162. R. Lübbers, H.F. Grünsteudel, A.I. Chumakov, G. Wortmann
 Density of Phonon States in Iron at High Pressures
 Science 287, 1250-1253 (2000). 

163. G.A. Stewart, S.J. Harker, M. Strecker, G. Wortmann
Mössbauer spectroscopy investigation of the IMMM-phase nickelates
Gd₂BaNiO₅ and Tm₂BaNiO₅
Phys. Rev. B 61, 6220-6226 (2000).

164. R. Lübbers, K. Rupprecht, G. Wortmann
High-Pressure Mössbauer Studies of Magnetism in RFe₂ Laves Phases and
Eu-chalcogenides, Hyperfine Interactions 128, 115 – 135 (2000). 

165. H.K. Mao, J. Xu, V.V. Struzhkin, J. Shu, R.J. Hemley, W. Sturhahn, M.Y. Hu,
E.E. Alp, L. Vocadlo, D. Alfè, G.D. Price, M.J. Gillan, M. Schwoerer-Böhning, 
D. Häusermann, P. Eng, G, Shen, H. Giefers, R. Lübbers. G. Wortmann
Phonon Density of States in Iron up to 153 GPa
Science 292, 914-916 (2001); 
see also Report with same authors in: Advanced Photon Source Research, No. 3, April 2000, 
p. 42 (APS at ANL, Argonne, IL 60439, U.S.A.) 

166. C. Grazioli, Z. Hu, M. Knupfer, G. Graw, G. Behr, M.S. Golden, J. Fink, H. Giefers,
G. Wortmann, K. Attenkofer
Characteristic temperature dependence of the 4f occupancy in the Kondo system CeSi₂
Phys. Rev. B 63, 115107-1-4 (2001).

167. K. Rupprecht, J. Lu, G. Wortmann, J. Przewoznik, J. Zukrowski
High-Pressure Mössbauer Studies of Magnetism in ScFe₂ and Sc_0.4Ti_0.6Fe₂ Laves Phases 
Acta Physica Polonica A 100, 789-797 (2001).

168. R. Niewa, Z. Hu, C. Grazioli, M.S. Golden, J. Fink, H. Giefers, G. Wortmann,
F.M.F. de Groot
XAS spectra of Ce₂MnN₃ at the Ce-M_4,5, Ce-L₃ and Mn-L_2,3 and N-K thresholds
J. Alloys Compounds 346, 129-133 (2002).

169 H. Giefers, R. Lübbers, K. Rupprecht, G. Wortmann, A.I. Chumakov, 
High-Pressure Phonon Spectroscopy of Oriented hcp Iron
ESRF Highlights 2000, p. 48.

170. K. Rupprecht, T. Friedmann, H. Giefers, G. Wortmann, B. Doyle, J. Zukrowski, 
High-pressure/high-temperature NFS study of magnetism in LuFe₂ and ScFe₂,
High Pressure Research 22, 189-194 (2002).

171. H. Giefers, R. Lübers, K. Rupprecht, G. Wortmann, D. Alfè, A.I. Chumakov, 
Phonon Density-of-States in Oriented hcp Iron by Nuclear Inelastic Scattering of
Synchrotron Radiation, 
High Pressure Research 22, 501-506 (2002).

172. Yu.S. Grushko, V.S. Koslov, L.I. Molkanov, A. Bolotov, G. Wortmann, E.A. Bychkov
¹²⁹I-Mössbauer study of MI-As₂Se₃ (M = Ag, Cu) superionic chalcohalide glasses 
Solid State Ionics 154-155, 265-271 (2002).

173. G. Wortmann, K. Rupprecht, H. Giefers, 
High-Pressure Studies of Magnetism and Lattice Dynamics by Nuclear Resonant Scattering of Synchrotron Radiation
Hyperfine Interactions 144/145, 103-117 (2002).

174. O. Leupold, K. Rupprecht, G. Wortmann
Electronic and Magnetic Transitions in Europium Compounds Studied by Nuclear Forward Scattering of Synchrotron Radiation
Structural Chemistry 14, 97-107 (2003).

175. U. Ponkratz, F. Porsch, G. Wortmann, W.B. Holzapfel,
X-ray diffraction studies on RECo₂ (RE = Pr, Nd, Sm, Tb) Laves phases under pressure
J. Alloys Compounds 359, 99-102 (2003).

176. C.K. Jayasankar, S. Surendra Babu, P. Babu, W. Sievers, Th. Tröster, G. Wortmann
A fluorescence study of Tb³⁺ doped tellurite glass under pressure
J. Phys.: Condens. Matter 16, 7007-7015 (2004).

177. H. Giefers, F. Porsch, G. Wortmann,
Kinetics of the disproportionation of SnO.
Solid State Ionics 176, 199-207 (2005).

178. G.A. Stewart, W.D. Hutchinson, A.V.J. Edge, K. Rupprecht, G. Wortmann, K. Nishmura, Y. Isikawa,
The magnetic properties of GdNiAl₄
J. Magn. Magn. Mat. 292, 72-78 (2005).

179. C.K. Jayasankar, V. Venkatramu, P. Babu, Th. Tröster, W. Sievers, G. Wortmann, W.B. Holzapfel,
High-pressure fluorescence study of Sm³⁺ doped borate and fluoborate glasses
J. Appl. Phys. 97, 093523-1-7(2005).

180. H. Giefers, F. Porsch, G. Wortmann,
High-pressure EXAFS and XRD investigation of unit cell parameters of SnO
Physica Scripta T115, 538-540 (2005).

181. H. Giefers, G. Wortmann, A.I. Chumakov, D. Alfe,
High-pressure Phonon Spectroscopy of Oriented hcp Iron
ESRF Highlights 2004, p. 19-20.

182. I. Serdons, R. Callens, R. Coussement, S. Gheysen, J. Ladriere, S. Morimoto, S. Nasu, Y. Yoda, J. Odeurs, G. Wortmann,
Stroboscopic Detection of the ¹⁸¹Ta-Mössbauer Resonance with Synchrotron Radiation
Nucl. Instrum. Methods (submitted).

183. H. Giefers, F. Porsch, G. Wortmann,
Thermal disproportionation of SnO under high pressure
Solid State Ionics 176, 1327-1332 (2005).

184. S. Surenda Babu, P. Babu, C.K. Jayasankar, Th. Tröster, W. Sievers, G. Wortmann,
Optical absorption and photoluminescence studies of Eu³⁺-doped phosphate and fluorophosphate glasses
J. Phys.: Condens. Matter 18, 1927--1938 (2006).

185. K. Rupprecht, U. Ponkratz, O. Leupold, G. Wortmann,
Magnetic Properties of EuS and EuSe at Extreme Pressures
ESRF Highlights 2005, p. 10-12.

186. H. Giefers, F. Porsch, G. Wortmann,
Structural study of SnO at high pressure
Physica B 373, 76-81 (2006).

187. S. Surenda Babu, P. Babu, C.K. Jayasankar, W. Sievers, Th. Tröster, G. Wortmann,
Optical absorption and photoluminescence studies of Eu³⁺-doped phosphate and fluorophosphate glasses
J. Luminescence (submitted).

188. V. Venkatramu, P. Babu, C.K. Jayasankar, Th. Tröster, W. Sievers and G. Wortmann,
High-pressure luminescence study of Tb³⁺-doped lithium fluoroborate glass
(in preparation)

189. H. Giefers, S. Koval, G. Wortmann, W. Sturhahn, E.E. Alp., M.Y. Hu,
Sn phonon density-of-states in textured SnO under high pressure
Phys. Rev. B (submitted).

190. C.K. Jayasankar, R. Balakrishnaiah, P. Babu, Th. Tröster, W. Sievers and G. Wortmann,
High-pressure fluorescence of Sm³⁺-doped K-Ba-Al phosphate glass
(in preparation)

191. H. Giefers, K. Rupprecht, U. Ponkratz, O. Leupold, G. Wortmann,
Pressure and Temperature Dependence of the phonon density-of-states in the Invar alloy Fe₆₅Ni₃₅
Phys. Rev. B (submitted).

192. A.I. Karasevskii, H.-J. Hesse, G. Wortmann,
Formation of an equilibrium heterogeneous structure at the valence transition in EuNi₂Ge₂
J. Phys.: Condens. Matter (in preparation).