A Dissolving Technique for Thin Platelet Preparation from Bulk Single Crystals
Dichroism studies1 of single crystals in electronic spectroscopy of transition metal complexes often require very thin parallel crystal platelets of usually less than 1 mm in thickness. This limitation on thickness arises from the often relatively high molar extinction coefficients, ∈ (ranging from 10 to 103 liter cm−1 mole−1), for spin-allowed Laporte forbidden bands in electronic spectra of transition metal complexes.2 The molar extinction coefficient for single crystals can be defined as ∈ = 2.303 O.D./bc where O.D. is the optical density, b is the thickness of the crystal in centimeters, and c is the concentration in moles per liter (usually in the order of 5 to 10 moles/liter for solid transition metal complexes). Thus to experimentally observe transmission bands in the normal optical density region of 2.0 or less, it is imperative either to dilute the compound by isomorphous doping in a nonabsorbing host crystal or, as is more often the case, to prepare very thin single crystal platelets from the bulk crystal.
KeywordsMolar Extinction Coefficient Transition Metal Complex Crystal Face Optical Bench Bulk Single Crystal
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