Optical Spectra and Chemical Bonding in Inorganic Compounds : Special Volume dedicated to Professor Jørgensen I Axel Christian Klixbüll Jørgensen (1931 2001) Whereof Man Cannot Speak: Some Scientific Vocabulary of Michael Faraday and Klixbüll Jørgensen The Variation of Slater Condon Parameters Fk and Racah Parameters B and C with Chemical Bonding in Transition Group Complexes Angular Overlap Model Parameters Influence of Crystal Field Parameters on Near Infrared to Visible Photon Upconversion in Ti2+ and Ni2+ Doped Halide Lattices Electronic Structures and Reduction Potentials of Cu(II) Complexes of [N N’ alkyl bis(ethyl 2 amino 1 cyclopentenecarbothioate)] (alkyl = ethyl propyl and butyl) Fine Tuning the Electronic Properties of [M(bpy)3]2+ Complexes by Chemical Pressure (M = Fe2+ Ru2+ Co2+ bpy = 2 2 bipyridine) A DFT Based Ligand Field Theory Electronic Properties and Bonding in Transition Metal Complexes: Influence of Pressure Structure Spectroscopy and Photochemistry of the [M(h 5 C5H5)(CO)2]2 Complexes (M = Fe Ru) Average One Center Two Electron Exchange Integrals and Exchange Interactions Christian Klixbüll Jørgensen and the Nature of the Chemical Bond in HArF Spectroscopy of Trivalent Praseodymium in Barium Yttrium Fluoride Rare Earth Ions their Spectroscopy of Cryptates and Related Complexes in Glasses Personal Notes.