Extending Dieke's diagram

The use of vacuum ultraviolet radiation (VUV: lambda < 200 nm) in lanthanid e spectroscopy has been triggered by the need for new luminescent materials for VUV excitation. In spite of this 'applied' incentive, the VUV studies have resulted in a wealth of new fundamental knowledge on the luminescence of lanthanides. Mere, the observation of many new intraconfigurational 4f(n ) transitions in the VUV is reported for various lanthanide ions. Based on these observations and energy level calculations an extension of the more t han 30-year old Dieke diagram from 40 000 to about 70 000 cm (-1) is obtain ed. New emitting 4f levels in the VUV are identified as well. (C) 2000 Else vier Science B.V. All rights reserved.